Long-term radial-velocity variations of the Sun as a star: The HARPS view

Stellar radial velocities play a fundamental role in the discovery of extrasolar planets and the measurement of their physical parameters as well as in the study of stellar physical properties. We investigate the impact of the solar activity on the radial velocity of the Sun using the HARPS spectrograph to obtain measurements that can be directly compared with those acquired in the extrasolar planet search programs. We use the Moon, the Galilean satellites, and several asteroids as reflectors to measure the radial velocity of the Sun as a star and correlate it with disc-integrated chromospheric and magnetic indexes of solar activity that are similar to stellar activity indexes. We discuss in detail the systematic effects that affect our measurements and the methods to account for them. We find that the radial velocity of the Sun as a star is positively correlated with the level of its chromospheric activity at about 95 percent significance level. The amplitude of the long-term variation measured in the 2006-2014 period is 4.98 \pm 1.44 m/s, in good agreement with model predictions. The standard deviation of the residuals obtained by subtracting a linear best fit is 2.82 m/s and is due to the rotation of the reflecting bodies and the intrinsic variability of the Sun on timescales shorter than the activity cycle. A correlation with a lower significance is detected between the radial velocity and the mean absolute value of the line-of-sight photospheric magnetic field flux density. Our results confirm similar correlations found in other late-type main-sequence stars and provide support to the predictions of radial velocity variations induced by stellar activity based on current models.Comment: 11 pages, 7 figures, 2 tables, 1 Appendix; accepted by Astronomy and Astrophysic

Ending Race-Based Pretextual Stops: Strategies For Eliminating America\u27s Most Egregious Police Practice

Pretextual policing is the practice of stopping motorists or pedestrians for minor offenses like traffic infractions in hopes of learning that the person stopped has committed a more serious crime. Pretextual policing is also the main reason Black Americans are so much more likely than white Americans to be subjected to encounters with law enforcement. Shockingly, even in its most explicitly racist form, pretextual policing does not violate the Fourth Amendment’s proscription against unreasonable searches and seizures. In fact, police can pull a driver over merely because he is Black without violating the Fourth Amendment, so long as the officer points to one of the hundreds of traffic laws most drivers violate every day as the objective basis for initiating the encounter. According to the Supreme Court, the subjective motivations of a police officer for conducting a stop are entirely irrelevant. During the 2020 special session of the Virginia General Assembly, the Commonwealth of Virginia passed landmark legislation eliminating many of the most commonly used pretexts, such as exhaust noise, objects hanging from the rearview mirror, tinted windows, jaywalking, and marijuana odor. Since doing so, many other states and localities have sought to pass similar reforms, recognizing the inordinate power police possess to do their jobs in a discriminatory manner without accountability. This article discusses the history of pretextual policing and urges policymakers and advocates to identify and pursue reforms to limit pretextual policing without jeopardizing true public safety

Composting paper and grass clippings with anaerobically treated palm oil mill effluent

Purpose The purpose of this study is to investigate the composting performance of anaerobically treated palm oil mill effluent (AnPOME) mixed with paper and grass clippings. Methods Composting was conducted using a laboratory scale system for 40 days. Several parameters were determined: temperature, mass reduction, pH, electrical conductivity, colour, zeta potential, phytotoxicity and final compost nutrients. Results The moisture content and compost mass were reduced by 24 and 18 %, respectively. Both final compost pH value and electrical conductivity were found to increase in value. Colour (measured as PtCo) was not suitable as a maturity indicator. The negative zeta potential values decreased from −12.25 to −21.80 mV. The phytotoxicity of the compost mixture was found to decrease in value during the process and the final nutrient value of the compost indicates its suitability as a soil conditioner. Conclusions From this study, we conclude that the addition of paper and grass clippings can be a potential substrate to be composted with anaerobically treated palm oil mill effluent (AnPOME). The final compost produced is suitable for soil conditioner

Space Velocities of L- and T-type Dwarfs

(Abridged) We have obtained radial velocities of a sample of 18 ultracool dwarfs (M6.5-T8) using high-resolution, near-infrared spectra obtained with NIRSPEC and the Keck II telescope. We have confirmed that the radial velocity of Gl 570 D is coincident with that of the K-type primary star Gl 570 A, thus providing additional support for their true companionship. The presence of planetary-mass companions around 2MASS J05591914-1404488 (T4.5V) has been analyzed using five NIRSPEC radial velocity measurements obtained over a period of 4.37 yr. We have computed UVW space motions for a total of 21 L and T dwarfs within 20 pc of the Sun. This population shows UVW velocities that nicely overlap the typical kinematics of solar to M-type stars within the same spatial volume. However, the mean Galactic (44.2 km/s) and tangential (36.5 km/s) velocities of the L and T dwarfs appear to be smaller than those of G to M stars. A significant fraction (~40%) of the L and T dwarfs lies near the Hyades moving group (0.4-2 Gyr), which contrasts with the 10-12% found for earlier-type stellar neighbors. Additionally, the distributions of all three UVW components (sigma_{UVW} = 30.2, 16.5, 15.8 km/s) and the distributions of the total Galactic (sigma_{v_tot} = 19.1 km/s) and tangential (sigma_{v_t} = 17.6 km/s) velocities derived for the L and T dwarf sample are narrower than those measured for nearby G, K, and M-type stars, but similar to the dispersions obtained for F stars. This suggests that, in the solar neighborhood, the L- and T-type ultracool dwarfs in our sample (including brown dwarfs) is kinematically younger than solar-type to early M stars with likely ages in the interval 0.5-4 Gyr.Comment: Accepted for publication in Ap

ANTIGENIC SPECIFICITIES ON MURINE SARCOMA CELLS : RECIPROCAL RELATIONSHIP BETWEEN NORMAL TRANSPLANTATION ANTIGENS (H-2) AND TUMOR-SPECIFIC IMMUNOGENICITY

Five methylcholanthrene-induced sarcomas were compared for their capacity to (a) absorb monospecific H-2 antisera, (b) induce tumor-specific immunity in syngeneic mice, and (c) metastasize early to the lungs. Comparison of the uptakes of monospecific H-2 antisera by the five different tumors showed that each of the tumors had a high, intermediate, or low surface representation of all of the seven specificities tested. No antigenic specificity was completely absent from any tumor, and no tumor had an unusually large or small amount of any individual specificity. The tumors could be placed in the sequence from one to five with respect to their H-2 antigenicity. The same five tumors were also ranked with respect to their capacity to induce a tumor-specific immune response in syngeneic mice. The tumor-specific immunogenicity had an inverse relationship to the H-2 antigenicity in that highly immunogenic tumors were those that had quantitatively less H-2 antigen on their surface and vice versa. Early metastases to the lung was associated with low levels of tumor-specific immunogenicity and high levels of H-2 antigenicity

Feat or futile: Students' perceptions of group work at a University of Technology in South Africa

The increase in student enrolment at tertiary institutions in South Africa over the past few years has necessitated the need for group work without sacrificing the standard and integrity of education. Research has shown that group work offers many advantages to both lecturers and students. Interactive attributes such as teamwork, co-operation skills, leadership qualities, communication skills and confidentiality developed during group work are highly sought-after skills by prospective employers. This quantitative study aimed to determine whether students are positively or negatively inclined towards group work, as well as other possible factors influencing group work at a university of technology (UoT) in South Africa. A structured, close-ended questionnaire was administered to 309 students enrolled for the Applied Communication Skills course. The data were analysed using statistical methods. The results revealed that listening skills and mutual respect were crucial to develop good interpersonal skills needed for effective group work. When working in groups, students tend towards collectivism and negative aspects of group work, such as social loafing, are often overseen to maintain harmony and avoid direct confrontation with other individuals in the group. It was also found that male students agreed more strongly with negative conflict resolution than female students. Overall, the study showed that despite several negative aspects, students tended to be positively inclined towards group work

Co-Occurrence and Characteristics of Patients With Axial Spondyloarthritis Who Meet Criteria for Fibromyalgia : Results From a UK National Register

The British Society for Rheumatology (BSR) Biologics Register in Ankylosing Spondylitis is funded by the BSR and they have receive funds for this from Pfizer, AbbVie and UCB. These companies receive advance copies of manuscripts and can provide comments but have no input into determining the topics for analysis, publication and no input into the work involved in this analysis. This analysis is part-funded by Arthritis Research UK (Grant No: 21378)Peer reviewedPublisher PD