Open volcanic systems: evidence for deep gas loss

2021 ◽  
Author(s):  
Marielle Collombet ◽  
Alain Burgisser ◽  
Mathieu Colombier ◽  
Elizabeth Gaunt
Keyword(s):  
High Pressures ◽  
Great Depth ◽  
High Likelihood ◽  
Porosity Distribution ◽  
Merapi Volcano ◽  
Eruptive Style ◽  
Magma Reservoirs ◽  
Gas Loss ◽  
Tungurahua Volcano ◽  
Rule Out

<p>Previous studies of Vulcanian eruptive products have shown that the respective volcanic conduits were filled for the<br>most part with low-porosity magma prior to eruption. Comparison with the theoretical porosity distribution<br>expected from closed-system degassing suggests that gas loss must have taken place at great depth within the<br>magmatic column. At such high pressures, however, porosities are low enough to rule out traditional gas loss<br>mechanisms. We tested if channelling, an outgassing mechanism based on bubble connection due to high crystal<br>content proposed to occur in mushy magma reservoirs, could also happen in volcanic conduits. We reanalysed<br>phenocryst, microlite, and porosity data from recent eruptions of Merapi volcano, Indonesia, Soufrière Hills<br>volcano, Montserrat, and Tungurahua volcano, Ecuador. Overall, these magmas had crystal contents high enough<br>for outgassing to occur by channelling. Gases could be channelled out of the magma columns at various levels<br>during ascent to yield mostly gas-depleted magma columns prior to explosive behaviour. Such outgassing by<br>channelling has thus the capacity to influence eruptive style. Depending on the phenocryst content, microlite<br>growth during ascent can either foster, or impede gas escape by channelling. Considering the pervasive occurrence<br>of microlites and ensuing high crystal contents in volcanic conduits, the high likelihood of channelling implies that<br>other outgassing mechanisms might not be as dominant as previously envisioned.</p>

Zenographic longitude systems and Jupiter's differential rotation

2001 ◽  
Vol 55 (1) ◽  
pp. 69-79
Author(s):  
C.B.E. Raymond Hide
Keyword(s):  
Differential Rotation ◽  
High Pressures ◽  
Rotation Period ◽  
Chemical Constituent ◽  
Great Depth ◽  
Electrically Conducting ◽  
Rotation Periods ◽  
The Earth ◽  
Cloud Patterns ◽  
Jovian Atmosphere

More than ten times the Earth in diameter and 300 times as massive, Jupiter is by far the largest planet in the Solar System. Fifth in order of distance from the Sun, which it orbits in 11.8626 years, Jupiter spins more rapidly than any other planet, with a rotation period of just under 10 hours. Unlike the Earth and the other ‘terrestrial’ planets, Jupiter's principal chemical constituent is hydrogen, mainly in the molecular gaseous form at the visible cloud levels in the Jovian atmosphere, but liquid at the high pressures prevailing at much deeper levels within the planet. The electrical conductivity increases from negligible values near the cloud levels to metallic values at great depth. Differential rotation between equatorial and higher-latitude regions of the Jovian atmosphere is reflected in the two systems of zenographic longitude introduced by observers monitoring the motions of atmospheric cloud patterns. These are Systems I and II with rotation periods T 1 =35430.003s (9h 50min 30.003s) and T 2 =35740.632s (9h 55min 40.632s) respectively. The most striking feature of the cloud patterns is the durable (but longitudinally mobile) Great Red Spot, originally known as ’Hooke's Spot’, the first observations of which were recorded in the Philosophical Transactions of The Royal Society of London at the very beginning of its first issue, published in 1665. Differential rotation between the atmosphere and underlying electrically conducting regions is reflected in the need for radio astronomers to use yet another zenographic longitude system—System III, with rotation period T 3 =35729.771s (9h 55min 29.711s)––when monitoring powerful Jovian sources of non-thermal electromagnetic radiation at decimeter and decametre wavelengths. These are located in the plasma envelope of Jupiter, which is closely tied to the deep interior of the planet by lines of force of the zenomagnetic field.

The Broad Applications of the Scanning Electron Microscope

1969 ◽  
Vol 27 ◽  
pp. 20-21
Author(s):  
C. T. Nightingale ◽  
S. E. Summers ◽  
T. P. Turnbull
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Light Microscopy ◽  
Surface Topography ◽  
Great Depth ◽  
Resolving Power ◽  
Depth Of Field ◽  
Pictorial Representations ◽  
Scanning Electron

The ease of operation of the scanning electron microscope has insured its wide application in medicine and industry. The micrographs are pictorial representations of surface topography obtained directly from the specimen. The need to replicate is eliminated. The great depth of field and the high resolving power provide far more information than light microscopy.

Visualization of Internal Skin Structures with the Scanning Electron Microscope

1969 ◽  
Vol 27 ◽  
pp. 46-47
Author(s):  
Emil Bernstein
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Great Depth ◽  
Hair Follicles ◽  
Depth Of Field ◽  
Pig Skin ◽  
Realistic Picture ◽  
Main Components ◽  
Scanning Electron

An interesting method for examining structures in g. pig skin has been developed. By modifying an existing technique for splitting skin into its two main components—epidermis and dermis—we can in effect create new surfaces which can be examined with the scanning electron microscope (SEM). Although this method is not offered as a complete substitute for sectioning, it provides the investigator with a means for examining certain structures such as hair follicles and glands intact. The great depth of field of the SEM complements the technique so that a very “realistic” picture of the organ is obtained.

Record Wear Studies by Scanning Electron Microscopy

1968 ◽  
Vol 26 ◽  
pp. 364-365
Author(s):  
M.D. Coutts ◽  
E.R. Levin ◽  
J.G. Woodward
Keyword(s):  
Electron Microscopy ◽  
Constant Velocity ◽  
Peak Velocity ◽  
Great Depth ◽  
Depth Of Focus ◽  
Sweep Frequency ◽  
Transmission Electron ◽  
Test Record ◽  
Lateral Mode ◽  
Scanning Electron

While record grooves have been studied by transmission electron microscopy with replica techniques, and by optical microscopy, the former are cumbersome and restricted and the latter limited by lack of depth of focus and resolution at higher magnification. With its great depth of focus and ease in specimen manipulation, the scanning electron microscope is admirably suited for record wear studies.A special RCA sweep frequency test record was used with both lateral and vertical modulation bands. The signal is a repetitive, constant-velocity sweep from 2 to 20 kHz having a duration and repetitive rate of approximately 0.1 sec. and a peak velocity of 5.5 cm/s.A series of different pickups and numbers of plays were used on vinyl records. One centimeter discs were then cut out, mounted and coated with 200 Å of gold to prevent charging during examination. Wear studies were made by taking micrographs of record grooves having 1, 10 and 50 plays with each stylus and comparing with typical “no-play” grooves. Fig. 1 shows unplayed grooves in a vinyl pressing with sweep-frequency modulation in the lateral mode.

A rapid method for the direct identification of paramyxovirus in canine CSF by ultracentrifugation and negative staining as a rule out for distemper

1990 ◽  
Vol 48 (3) ◽  
pp. 594-595
Author(s):  
W.L. Steffens ◽  
M.B. Ard ◽  
C.E. Greene ◽  
A. Jaggy
Keyword(s):  
Subacute Sclerosing Panencephalitis ◽  
Clinical Signs ◽  
Viral Disease ◽  
Etiologic Agent ◽  
Mucosal Inflammation ◽  
Worldwide Distribution ◽  
Negative Stain ◽  
Viral Particles ◽  
Systemic Manifestations ◽  
Rule Out

Canine distemper is a multisystemic contagious viral disease having a worldwide distribution, a high mortality rate, and significant central neurologic system (CNS) complications. In its systemic manifestations, it is often presumptively diagnosed on the basis of clinical signs and history. Few definitive antemortem diagnostic tests exist, and most are limited to the detection of viral antigen by immunofluorescence techniques on tissues or cytologic specimens or high immunoglobulin levels in CSF (cerebrospinal fluid). Diagnosis of CNS distemper is often unreliable due to the relatively low cell count in CSF (<50 cells/μl) and the binding of blocking immunoglobulins in CSF to cell surfaces. A more reliable and definitive test might be possible utilizing direct morphologic detection of the etiologic agent. Distemper is the canine equivalent of human measles, in that both involve a closely related member of the Paramyxoviridae, both produce mucosal inflammation, and may produce CNS complications. In humans, diagnosis of measles-induced subacute sclerosing panencephalitis is through negative stain identification of whole or incomplete viral particles in patient CSF.

Impairment Questions and Answers

1999 ◽  
Vol 4 (4) ◽  
pp. 4-4
Keyword(s):  
Symptom Validity ◽  
Validity Testing ◽  
Symptom Validity Testing ◽  
Negative Results ◽  
Tunnel Vision ◽  
Questions And Answers ◽  
Blurry Vision ◽  
Fatigue Evaluation ◽  
Choice Testing ◽  
Rule Out

Abstract Symptom validity testing, also known as forced-choice testing, is a way to assess the validity of sensory and memory deficits, including tactile anesthesias, paresthesias, blindness, color blindness, tunnel vision, blurry vision, and deafness—the common feature of which is a claimed inability to perceive or remember a sensory signal. Symptom validity testing comprises two elements: A specific ability is assessed by presenting a large number of items in a multiple-choice format, and then the examinee's performance is compared with the statistical likelihood of success based on chance alone. Scoring below a norm can be explained in many different ways (eg, fatigue, evaluation anxiety, limited intelligence, and so on), but scoring below the probabilities of chance alone most likely indicates deliberate deception. The positive predictive value of the symptom validity technique likely is quite high because there is no alternative explanation to deliberate distortion when performance is below the probability of chance. The sensitivity of this technique is not likely to be good because, as with a thermometer, positive findings indicate that a problem is present, but negative results do not rule out a problem. Although a compelling conclusion is that the examinee who scores below probabilities is deliberately motivated to perform poorly, malingering must be concluded from the total clinical context.

Case Exercise: Toxic Exposure-Related Illness: Causation, Diagnosis, and Permanent Impairment

2007 ◽  
Vol 12 (2) ◽  
pp. 4-8
Author(s):  
Frederick Fung
Keyword(s):  
Concentration Level ◽  
Treatment Plan ◽  
Toxic Exposure ◽  
Dose Response Relationship ◽  
Specialty Board ◽  
History Of ◽  
Subjective Complaints ◽  
Based Medicine ◽  
Illness Causation ◽  
Rule Out

Abstract A diagnosis of toxic-related injury/illness requires a consideration of the illness related to the toxic exposure, including diagnosis, causation, and permanent impairment; these are best performed by a physician who is certified by a specialty board certified by the American Board of Preventive Medicine. The patient must have a history of symptoms consistent with the exposure and disease at issue. In order to diagnose the presence of a specific disease, the examiner must find subjective complaints that are consistent with the objective findings, and both the subjective complaints and objective findings must be consistent with the disease that is postulated. Exposure to a specific potentially causative agent at a defined concentration level must be documented and must be sufficient to induce a particular pathology in order to establish a diagnosis. Differential diagnoses must be entertained in order to rule out other potential causes, including psychological etiology. Furthermore, the identified exposure at the defined concentration level must be capable of causing the diagnosis being postulated before the examiner can conclude that there has been a cause-and-effect relationship between the exposure and the disease (dose-response relationship). The evaluator's opinion should make biological and epidemiological sense. The treatment plan and prognosis should be consistent with evidence-based medicine, and the rating of impairment must be based on objective findings in involved systems.

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