A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

VII.—Report on the total solar eclipse of April 6, 1875

1878 ◽  
Vol 169 ◽  
pp. 139-154 ◽  
Keyword(s):  
Short Duration ◽  
Solar Eclipse ◽  
Royal Society ◽  
Total Solar Eclipse ◽  
The Other ◽  
Easy Task ◽  
Other Hand ◽  
The One

It is never an easy task to make out the plan of operations for the observation of a phenomenon so rare and of such short duration as a total solar eclipse. We must be careful on the one hand not to risk failure by the adoption of new and uncertain methods, and on the other hand we must bear in mind that the mere repetition of what has been done before does not justify any large expenditure of time and money. In drawing out the instructions for the expedition the Committee of the Royal Society had to consider in how far the old methods could be perfected, and in how far new ones should be tried.

scholarly journals Primordial black holes and scotogenic dark matter

2021 ◽  
pp. 2150139
Author(s):  
Teruyuki Kitabayashi
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Energy Scale ◽  
The Other ◽  
Initial Mass ◽  
Primordial Black Holes ◽  
Upper Limit ◽  
Other Hand

We study the effect of the scotogenic dark matter on the primordial black holes (PBHs) and vice versa. We show that if the PBHs evaporate in the radiation dominated era, the upper limit of the initial mass of the PBHs [Formula: see text] should be constrained as [Formula: see text] for [Formula: see text] TeV scotogenic dark matter [Formula: see text] TeV is the most appropriate energy scale in the scotogenic model). On the other hand, if the PBHs evaporate in the PBH dominated era, a quite heavy scotogenic dark matter ([Formula: see text] GeV) for [Formula: see text] may be allowed.

scholarly journals KARAKTERISTIK BADAI TROPIS DAN DAMPAKNYA TERHADAP ANOMALI HUJAN DI INDONESIA(TROPICAL CYCLONE CHARACTERISTIC AND ITS IMPACT ON RAINFALL ANOMALY IN INDONESIA)

Agromet ◽  
2007 ◽  
Vol 21 (2) ◽  
pp. 61 ◽  
Author(s):  
N. Dyahwathi ◽  
S. Effendy ◽  
E.S. Adiningsih
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Short Duration ◽  
High Intensity ◽  
Rainfall Anomaly ◽  
Physical Characteristics ◽  
The Other ◽  
Research Purpose ◽  
Small Scale ◽  
Other Hand

<p>Tropical cyclone never reached Indonesia area but its impact able to cause disaster to this country. Some research indicated effect of tropical cyclone due to high intensity the rain in short duration in some location but drought in another. Tropical cyclone often followed by small scale tornado callled ’puting beliung’ that cause local or regional damage. This research purpose to analyze physical characteristics of tropical cyclone at period January-March 2004 in south Hindia Sea. The Fay is a strong tropical cyclone has increase rainfall until 32 ms-1 and rainfaal on 47% Java station rainfall. On the other hand, The Ken is a weak tropical cyclone only cause higher wind speed and rainfall are 8 ms-1 and 18% Java station rainfall, respectively.</p><p>------------------------------------------------------------------------</p><p>Meskipun siklon tropis tidak pernah terjadi di Indonesia namun dampaknya sering berpengaruh terhadap Indonesia. Hasil berbagai penelitian menunjukkan bahwa siklon tropis menyebabkan hujan intensitas yang tinggi dalam waktu singkat pada suatu wilayah, dan juga menyebabkan kekeringan di daerah lain. Siklon tropis sering diikuti terjadinya puting beliung dengan daya rusak bersifat lokal hingga regional. Penelitian ini bertujuan untuk menganalisis karakteristik fisik siklon tropis di Samudera Hindia bagian selatan pada periode puncak terjadinya siklon yakni, Januari-Maret 2004. Analisis dilakukan terhadap dua siklon yang terjadi pada periode pengamatan yaitu siklon Fay (siklon kuat) dan siklon Ken (siklon lemah). Dampak siklon Fay terhadap peningkatan kecepatan angin menjadi 32 ms-1 dan peningkatan hujan yang signifikan padak 47% stasiun hujan di Jawa. Sedangkan siklon Ken hanya menyebabkan kecepatan angin meningkat sebesar 8 ms-1 dan peningkatan hujan pada 8% stasiun hujan di pulau Jawa.</p>

scholarly journals An Almahata Sitta EL3 fragment: Implications for the Unique Thermal History of Enstatite Chondrites

2021 ◽  
Author(s):  
Makoto Kimura ◽  
Michael K. Weisberg ◽  
Asako Takaki ◽  
Naoya Imae ◽  
Akira Yamaguchi
Keyword(s):  
High Temperature ◽  
Short Duration ◽  
Thermal History ◽  
Parent Body ◽  
The Other ◽  
Thermal Event ◽  
Other Hand ◽  
Typical Type ◽  
History Of ◽  
Type 3

Abstract Almahata Sitta is a polymict breccia, consisting of many kinds of clasts. Here we present our mineralogical and petrological results on an EL3 fragment, MS-177 from Almahata Sitta. This fragment shows a typical type 3 chondritic texture, consisting of well-defined chondrules often with olivine, isolated silicate minerals, and opaque nodules. Although these components are typical of EL3 chondrites, the mineral abundances and compositions are different from the other EL3s. Diopside is highly abundant. On the other hand, perryite and daubreelite were not found. The major pyroxene is orthoenstatite, and the silica phase is quartz. Fe-Ni metal has relatively high P contents. Troilite is enriched in Cr and Mn. Keilite and buseckite are present in MS-177. From the mineralogy and texture, MS-177 experienced a high-temperature event under subsolidus conditions. Shock-induced heating for a short duration might explain this high-temperature event. This is supported by shock-induced darkened feature of MS-177. We suggest that other E3 chondrites also experienced heating events under such subsolidus conditions on their parent bodies. On the other hand, the high abundance of diopside cannot be explained by a secondary thermal event and may have been a primary feature of MS-177, formed before accretion to the parent body.

scholarly journals An Almahata Sitta EL3 fragment: implications for the complex thermal history of enstatite chondrites

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
M. Kimura ◽  
M. K. Weisberg ◽  
A. Takaki ◽  
N. Imae ◽  
A. Yamaguchi
Keyword(s):  
High Temperature ◽  
Short Duration ◽  
Thermal History ◽  
Parent Body ◽  
The Other ◽  
Thermal Event ◽  
Other Hand ◽  
Typical Type ◽  
History Of ◽  
Type 3

AbstractAlmahata Sitta is a polymict breccia, consisting of many kinds of clasts. Here we present our mineralogical and petrological results on an EL3 fragment, MS-177 from Almahata Sitta. This fragment shows a typical type 3 chondritic texture, consisting of well-defined chondrules, isolated silicate minerals, and opaque nodules. Most chondrules are enstatite-rich with some having olivine. Although these components are typical of EL3 chondrites, the mineral abundances and compositions are different from the other EL3s. Diopside is unusually abundant in MS-177. On the other hand, perryite and daubreelite were not found. The major pyroxene is orthoenstatite, and the silica phase is quartz. Fe–Ni metal has relatively high P contents. Troilite is enriched in Cr and Mn. Keilite and buseckite are present in MS-177. From the mineralogy and texture, MS-177 experienced a high-temperature event under subsolidus conditions. Shock-induced heating for a short duration might explain this high-temperature event. We suggest that other E3 chondrites also experienced heating events under such subsolidus conditions on their parent bodies. On the other hand, the high abundance of diopside cannot be explained by a secondary thermal event and may have been a primary feature of MS-177, formed before accretion to the parent body.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

Don’t Put Me in This Group

2019 ◽  
Vol 50 (2) ◽  
pp. 80-93
Author(s):  
Jort de Vreeze ◽  
Christina Matschke
Keyword(s):  
Positive Emotions ◽  
Negative Emotions ◽  
Negative Information ◽  
The Self ◽  
The Other ◽  
Other Hand ◽  
Group Memberships

Abstract. Not all group memberships are self-chosen. The current research examines whether assignments to non-preferred groups influence our relationship with the group and our preference for information about the ingroup. It was expected and found that, when people are assigned to non-preferred groups, they perceive the group as different to the self, experience negative emotions about the assignment and in turn disidentify with the group. On the other hand, when people are assigned to preferred groups, they perceive the group as similar to the self, experience positive emotions about the assignment and in turn identify with the group. Finally, disidentification increases a preference for negative information about the ingroup.

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