scholarly journals The Appearance and Disappearance of Exocomet Gas Absorption

2015 ◽  
Vol 2015 ◽  
pp. 1-20 ◽  
Author(s):  
Barry Y. Welsh ◽  
Sharon L. Montgomery
Keyword(s):  
Spectral Data ◽  
Spectral Type ◽  
Gas Absorption ◽  
Stellar Systems ◽  
Activity Levels ◽  
Line Profiles ◽  
Short Term ◽  
Line Absorption ◽  
First Time ◽  
Parent Star

CaII K-line (3933 Å) absorption profiles observed towards 15 A-type and two B-type stars with known (or suspected) debris disks, in addition to archival spectral data for three A-type stars, are presented. Inspection of the extracted CaII K-line absorption lines has determined that one late B-type (HD 58647) and four new A-type (HD 56537, HD 64145, HD 108767, and HD 109573) stellar systems exhibit short-term (night-to-night) absorption variation within these profiles. This variability is due to the liberation of gas from falling evaporating bodies (the so-called FEBs activity) on the grazing approach of exocomets towards their parent star. Also we present archival spectra of the FeIλ3860 Å and CaII K-lines towardsβPictoris (HD 39060) that, for the first time, reveal the absorption signatures of FEB activity at similar velocities inbothline profiles. FEB-hosting stars seem to be of an earlier type (on average spectral type Al.8 as compared with A3.1) than those where no FEB activity has been observed. This could be due to stellar activity levels (such as chromospheric activity or nonradial pulsations) being of a higher level within the atmospheres of these hotter A-type stars.

scholarly journals Short-Term Spectroscopic Variations of the Be Star 11 Cam

1987 ◽  
Vol 92 ◽  
pp. 93-94
Author(s):  
J. Chauville ◽  
M. Alvarez ◽  
J.P. Sareyan ◽  
L. Ballereau ◽  
R. Michel
Keyword(s):  
Spectral Type ◽  
Balmer Line ◽  
Line Profiles ◽  
Short Term ◽  
Visual Magnitude ◽  
Be Star ◽  
Long Term Variations

11 Cam (HD 32343 = HR 1622) is a so-called “pole-on” Be star known for its long term variations, already noted by Merrill and Burwell (1943). Recent determinations of visual magnitude and spectral type are V = 5.222 and B2.5Ve (Rufener, 1981). The Balmer line profiles, especially Hα, have been frequently studied; Briot (1971), for instance, measured 40 and 4.9 Å equivalent widths for Hα and Hβ respectively; the Hα/Hβ peak to continuum ratio is 6.43/2.02 according to Gray and Marlborough (1974) who give v sin i = 131 km s-1, close to the value of 140 km s-1 adopted by Kogure (1968).

scholarly journals Chemical Constituents of the Marine Sponge Aaptos aaptos (Schmidt, 1864) and Their Cytotoxic Activity

2021 ◽  
Vol 16 (2) ◽  
pp. 1934578X2199334
Author(s):  
Do Thi Trang ◽  
Bui Huu Tai ◽  
Dan Thuy Hang ◽  
Pham Hai Yen ◽  
Phan Thi Thanh Huong ◽  
...  
Keyword(s):  
Cytotoxic Activity ◽  
Spectral Data ◽  
Absolute Configuration ◽  
Marine Sponge ◽  
Chemical Constituents ◽  
2D Nmr ◽  
Extensive Analysis ◽  
First Time ◽  
Tddft Method ◽  
Mcf 7

Seven compounds (1-7) were isolated from the marine sponge Aaptos aaptos living in the Vietnamese sea. Their structures were determined as 2 hours, 5 H,7 H,9 H-9 S-hydroxy-imidazo[1,5- α]pyridine-1,3-dione (1), 3-([9-methylhexadecyl]oxy)propane-1,2-diol 2, 2,3-dihydro-2,3-dioxoaaptamine (3), indol-3-aldehyde (4), methyl indole-3-carboxylate (5) 4-hydroxy-5-(indole-3-yl)−5-oxo-pentan-2-one (6), and thymidine (7) by extensive analysis of HR-ESI-MS, 1D, and 2D NMR spectral data, as well as by comparison of the spectral data with those reported in the literature. In addition, the absolute configuration of 1 was determined from the experimental ECD spectrum and comparison of this with the theoretical ECD calculations using the TDDFT method. Compounds 1 and 2 were isolated from nature for the first time. Compound 3 induced cytotoxic activity against SK-LU-1, MCF-7, HepG2, and SK-Mel-2 cell lines with IC50 values of 41.27 ± 2.63, 40.70 ± 2.65, 34.31 ± 3.43, and 36.63 ± 1.40 µM, respectively.

Representing Social Construction in Consumer Activities: Single-Period and Multi-Period Activity Production

1994 ◽  
Vol 5 (3) ◽  
pp. 139-156
Author(s):  
Steven D. Silver
Keyword(s):  
Social Construction ◽  
Evolutionary Process ◽  
Decision Makers ◽  
Maximization Problem ◽  
Activity Levels ◽  
Short Term ◽  
Subsequent Period ◽  
Single Period ◽  
The Social ◽  
Endogenous Variables

Consumers are seen as limited decision makers who set short-term activity levels from their budgets, stocks of experience, and values following a preference-maximizing heuristic. Disturbances to activity levels in their evolution by exogeneties of social and economic environments, and the feedback of activity levels which agents have no systematic ability to anticipate, reset stock and value levels through the interactive relationships among endogenous variables. Agents then solve the maximization problem for a subsequent period using stock and value levels as modified by the evolutionary process. The dependence of a single-period decision on the stock and value constructs is examined and forms for the dynamic evolution of stock and value constructs that represent the feedback of activity levels to stock and value levels are also introduced. Implications of these forms for the social construction of activities are discussed.

Chemical components of the rhizomes of Drynaria fortunei (KUNZE) J. Sm. (polypodiaceae) in Vietnam

2011 ◽  
Vol 76 (9) ◽  
pp. 1133-1139 ◽  
Author(s):  
Pham Thi Nhat Trinh ◽  
Nguyen Cong Hao ◽  
Phan Thanh Thao ◽  
Le Tien Dung
Keyword(s):  
Data Analysis ◽  
Spectral Data ◽  
Phenolic Acid ◽  
Ethanol Extract ◽  
Chemical Components ◽  
Spectroscopic Methods ◽  
Phenylpropanoid Glycoside ◽  
Spectral Data Analysis ◽  
First Time

From the ethanol extract of Drynaria fortunei (KUNZE) J. Sm., a new phenylpropanoid glycoside, fortunamide (1), was isolated and characterized by spectroscopic methods. Together with a new glycoside, 9 known compounds, including three curcuminoids (2–4), two isoprenylated flavonoids (5, 6), two flavonoids (7, 8), one monoterpenoid (9) and one phenolic acid (10) were isolated and identified by spectral data analysis from the rhizomes of Drynaria fortunei (KUNZE) J. Sm. Eight of them were isolated from Drynaria fortunei (KUNZE) J. Sm. for the first time.

scholarly journals Doppler Tomography in 2D and 3D of the X-ray Binary Cyg X-1 for June 2007

2011 ◽  
Vol 7 (S282) ◽  
pp. 201-202 ◽  
Author(s):  
O. I. Sharova ◽  
M. I. Agafonov ◽  
E. A. Karitskaya ◽  
N. G. Bochkarev ◽  
S. V. Zharikov ◽  
...  
Keyword(s):  
Binary System ◽  
Spectral Data ◽  
Inclination Angle ◽  
Tomographic Reconstruction ◽  
Orbital Plane ◽  
National Observatory ◽  
Doppler Tomography ◽  
X Ray ◽  
2D And 3D ◽  
First Time

AbstractThe 2D and 3D Doppler tomograms of X-ray binary system Cyg X-1 (V1357 Cyg) were reconstructed from spectral data for the line HeII 4686Å obtained with 2-m telescope of the Peak Terskol Observatory (Russia) and 2.1-m telescope of the Mexican National Observatory in June, 2007. Information about gas motions outside the orbital plane, using all of the three velocity components Vx, Vy, Vz, was obtained for the first time. The tomographic reconstruction was carried out for the system inclination angle of 45°. The equal resolution (50 × 50 × 50 km/s) is realized in this case, in the orbital plane (Vx, Vy) and also in the perpendicular direction Vz. The checkout tomograms were realized also for the inclination angle of 40° because of the angle uncertainty. Two versions of the result showed no qualitative discrepancy. Details of the structures revealed by the 3D Doppler tomogram were analyzed.

Regulating short-term rentals: Joined cases C-724/18 and C-727/18 Cali Apartments

2021 ◽  
pp. 1023263X2110146
Author(s):  
Tania Pantazi
Keyword(s):  
Consumer Protection ◽  
European Court Of Justice ◽  
Short Term ◽  
European Regulation ◽  
Future Developments ◽  
Online Platforms ◽  
Court Of Justice ◽  
European Court ◽  
Tourist Accommodation ◽  
First Time

The increase in short-term rentals via online platforms has captured the attention of scholars and regulators. Short-term letting is now considered a considerable alternative to traditional tourist accommodation contracts, challenging matters such as conditions in the housing market and consumer protection. Online platforms, such as Airbnb, Booking.com , Expedia and Tripadvisor, now provide offers for short-term accommodation contracts along with traditional accommodation options (hotels, hostels, apartments). The recent decision of the European Court of Justice in Joined cases C-724/18 and C-727/18 addresses for the first time the issue of regulation of short-term rentals in Member States and evaluates a national authorization scheme in light of the Services Directive. The present paper provides a brief background of European regulation affecting short-term rentals and discusses the judgment and its implications for future developments.

A new natural indole and three aporphine alkaloids from Monodora bevipes Benth. (Annonaceae)

2017 ◽  
Vol 6 (7) ◽  
pp. 40-43
Author(s):  
Dade J.M. Eric ◽  
Coulibali Siomenan ◽  
Kouamé Bi Koffi François Prévost ◽  
Kablan Ahmont Landry Claude ◽  
Kodjo Charles ◽  
...  
Keyword(s):  
Spectral Data ◽  
Pharmaceutical Journal ◽  
First Time

Four compounds were isolated from the leaves of Monodora brevipes Benth. (Annonaceae). Among them, one new natural indole named 5-formylindole (1) and three known aporphine alkaloids: (+)-roemeroline (2); (+)-corydine (3) and (+)-menispermine (4). They were isolated for the first time from this species. The structures of these compounds were established according to their spectral data (NMR, SM, IR and UV).Eric et al., International Current Pharmaceutical Journal, June 2017, 6(7): 40-43http://www.icpjonline.com/documents/Vol6Issue7/01.pdf

(+)-3α-Hydroxylupanine, a new alkaloid from Ammopiptanthus mongolicus (MAXIM.) CHENG F.

1990 ◽  
Vol 55 (5) ◽  
pp. 1257-1265 ◽  
Author(s):  
Bohumil Proksa ◽  
Dušan Uhrín ◽  
Stanislava Uhrínová ◽  
Eduard Grossmann ◽  
Dangaa Selenge ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Spectral Data ◽  
Ammopiptanthus Mongolicus ◽  
First Time

From leaves of Ammopiptanthus mongolicus (MAXIM.) CHENG F. were isolated (+)-3α-hydroxylupanine (I), (1R)-3-O-methyl[1,2,4/3,5,6]-inositol (V), salicylic acid, (-)-piptanthine (III), 7-hydroxy-4'-methoxyisoflavone (VIII), 7,3'-dihydroxy-4'-methoxyisoflavone (X) and 4'-methoxyisoflavone-7-β-D-glucopyranoside (IX). All the compounds were characterized on the basis of spectral data; the first three compounds were isolated from this material for the first time.

scholarly journals Apparent Variation of v sin i and Rotational Modulation in Be Stars

2004 ◽  
Vol 215 ◽  
pp. 93-94
Author(s):  
C. Neiner ◽  
S. Jankov ◽  
M. Floquet ◽  
A. M. Hubert
Keyword(s):  
Fourier Transform ◽  
Magnetic Dipole ◽  
Be Stars ◽  
Line Profiles ◽  
Transform Method ◽  
Rotational Modulation ◽  
Be Star ◽  
Apparent Variation ◽  
The Fourier Transform ◽  
First Time

v sin i was determined by applying the Fourier transform method to the line profiles of two classical Be Stars. A variation is observed in the apparent v sin i which corresponds to the main frequencies associated to nrp modes. Rotational modulation is observed in wind sensitive UV lines of the Be star ω Ori and is associated with an oblique magnetic dipole which is discovered for the first time in a classical Be star.

scholarly journals A SLR Pre-Processing Algorithm Based on Satellite Signature Effect

2021 ◽  
Vol 11 (19) ◽  
pp. 8880
Author(s):  
Bowen Guan ◽  
Cunbo Fan ◽  
Ning An ◽  
Ricardo Cesar Podesta ◽  
Dra Ana Pacheco ◽  
...  
Keyword(s):  
Mean Value ◽  
Observation Data ◽  
Short Term ◽  
Error Sources ◽  
Effect Model ◽  
The Mean ◽  
The Stability ◽  
First Time ◽  
Satellite Signature Effect

As one of the major error sources, satellite signature effect should be reduced or even erased from the distribution of the post-fit residuals to improve the ranging precision. A simulation of satellite signature effect removal process for normal point algorithm is conducted based on a revised model of satellite response, which fully considers the structural and distribution characteristics of retroreflectors. In order to eliminate both long-term and short-term satellite signature effect, a clipping method for SLR data processing is proposed by defining the clipping location as 5.6 mm away from the mean value of the long-term fit residuals to select effective returns for normal points. The results indicate that, compared to normal points algorithm, the RMS per NP of LAGEOS-1 observation data processed by the clipping method is reduced from 62.90 ± 9.9 mm to 56.07 ± 4.69 mm, and the stability of RMS is improved 53%. This study improves the satellite signature effect model and simulates the fluctuation of normal points caused by satellite signature effect for the first time. The new method based on the simulation of satellite signature effect has stronger robustness and applicability, which can further minimize the influence of satellite signature effect on the SLR production and significantly improve the data property.

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