Radial mixing in the outer Milky Way disk caused by an orbiting satellite

Using test particle simulations we examine the structure of the outer Galactic disk as it is perturbed by a satellite in a tight eccentric orbit about the Galaxy. A satellite of mass a few times 10^9 Msol can heat the outer Galactic disk, excite spiral structure and a warp and induce streams in the velocity distribution. We examine particle eccentricity versus the change in mean radius between initial and current orbits. Correlations between these quantities are reduced after a few satellite pericenter passages. Stars born in the outer galaxy can be moved in radius from their birth positions and be placed in low eccentricity orbits inside their birth radii. We propose that mergers and perturbations from satellite galaxies and subhalos can induce radial mixing in the stellar metallicity distribution.Comment: minor revisio

The Great Depression Two Kansas Diaries

During the decade of the 1930s the nation plunged from prosperity and great expectations into a sharp decline that adversely affected a greater percentage of people than any economic crisis before or since. During the Great Depression 25 percent of the nation\u27s work force became unemployed. No state was unaffected, and both cities and farms suffered, although each section of the economy displayed a different set of problems. For most urban dwellers the extent and depth of the crisis was measured by employment. Studs Terkel found the clearest, most succinct definition of the Depression when a once unemployed laborer said: The Depression ended in 1936, the day I got a job. 1 For farmers in western Kansas the Depression began in 1933 with thirty dust days and ended in 1939 when the rains came. The hard times were a staggering ordeal, both emotionally and economically, for millions of people, but some found the 1930s to be a time of opportunity while the Depression rolled over others without leaving a mark. Just how drastic the change could be and how disparate the impact of the Great Depression could be is illustrated in diaries kept by two Kansas women between 1935 and 1939. At the onset of the Depression, the two women seemed similar. They had received comparable, if not identical, educations in similar rural settings-small country towns. Both came from the British Protestant tradition, although one was Presbyterian and the other Methodist. They were of the same white, middle-class generation. Their values base and prior status were much the same, but the details of their lives were to determine how they reacted to the troubled times. Lucy Mabel Holmes was born to John and Frances M. Holmes in Baldwin, a small, rural town in down-state Illinois, on 10 June 1878. John Holmes was a construction contractor and carpenter. In 1890 the family moved to Topeka and Mabel (who used her middle name) lived there for the rest of her life. In 1935, when she began writing in her diary, she was fifty-seven years old, unmarried, and living with her sister, Elma, two years her senior, who was also unmarried. Elma had taught in Lafayette Elementary School when she first came to Topeka but was teaching at Randolph School in 1935. Mabel had served as secretary of the American Railway Express Company and as a stenographer for the Alliance Cooperative Investment Company before moving to a similar position at the Kansas State Horticultural Department. Her work schedule was quite flexible, and she frequently mentioned that she spent only the morning or afternoon at the office and took off time for long and short vacations.2 Elsie May Long wS\s born 31 October 1892, in Holton, Kansas, the second daughter of Alfonso Houston and Mary Jane Long. She attended public school in Holton. In 1909 or 1910, the family moved to a Ford County farm where her father worked for Charley E. Haywood as an informal foreman or manager. Elsie attended the Fowler Friends Academy for one year, then taught in a one-room country school for two years. On her twenty-second birthday (31 October 1914) she married Clarence O. Haywood, the son of her father\u27s employer. They began their married life on a wheat farm twelve miles north of Fowler, Kansas, and about twenty-five miles southwest of Dodge City. Two sons were born to the couple, Harold in 1915 and Bobby in 1921

The Great Depression Two Kansas Diaries

During the decade of the 1930s the nation plunged from prosperity and great expectations into a sharp decline that adversely affected a greater percentage of people than any economic crisis before or since. During the Great Depression 25 percent of the nation\u27s work force became unemployed. No state was unaffected, and both cities and farms suffered, although each section of the economy displayed a different set of problems. For most urban dwellers the extent and depth of the crisis was measured by employment. Studs Terkel found the clearest, most succinct definition of the Depression when a once unemployed laborer said: The Depression ended in 1936, the day I got a job. 1 For farmers in western Kansas the Depression began in 1933 with thirty dust days and ended in 1939 when the rains came. The hard times were a staggering ordeal, both emotionally and economically, for millions of people, but some found the 1930s to be a time of opportunity while the Depression rolled over others without leaving a mark. Just how drastic the change could be and how disparate the impact of the Great Depression could be is illustrated in diaries kept by two Kansas women between 1935 and 1939. At the onset of the Depression, the two women seemed similar. They had received comparable, if not identical, educations in similar rural settings-small country towns. Both came from the British Protestant tradition, although one was Presbyterian and the other Methodist. They were of the same white, middle-class generation. Their values base and prior status were much the same, but the details of their lives were to determine how they reacted to the troubled times. Lucy Mabel Holmes was born to John and Frances M. Holmes in Baldwin, a small, rural town in down-state Illinois, on 10 June 1878. John Holmes was a construction contractor and carpenter. In 1890 the family moved to Topeka and Mabel (who used her middle name) lived there for the rest of her life. In 1935, when she began writing in her diary, she was fifty-seven years old, unmarried, and living with her sister, Elma, two years her senior, who was also unmarried. Elma had taught in Lafayette Elementary School when she first came to Topeka but was teaching at Randolph School in 1935. Mabel had served as secretary of the American Railway Express Company and as a stenographer for the Alliance Cooperative Investment Company before moving to a similar position at the Kansas State Horticultural Department. Her work schedule was quite flexible, and she frequently mentioned that she spent only the morning or afternoon at the office and took off time for long and short vacations.2 Elsie May Long wS\s born 31 October 1892, in Holton, Kansas, the second daughter of Alfonso Houston and Mary Jane Long. She attended public school in Holton. In 1909 or 1910, the family moved to a Ford County farm where her father worked for Charley E. Haywood as an informal foreman or manager. Elsie attended the Fowler Friends Academy for one year, then taught in a one-room country school for two years. On her twenty-second birthday (31 October 1914) she married Clarence O. Haywood, the son of her father\u27s employer. They began their married life on a wheat farm twelve miles north of Fowler, Kansas, and about twenty-five miles southwest of Dodge City. Two sons were born to the couple, Harold in 1915 and Bobby in 1921

Unplighted Troths: Causes for Divorce in a Frontier Town Toward The End of the Nineteenth Century

W elcome to Dodge City, the biggest, wildest, wickedest little city on the continent, was the exuberant greeting given out-of-town visitors to Dodge\u27s Fourth ofJuly celebration in 1883. The assessment projected was a selfcongratulatory one shared and frequently envied by the rest of the United States. Dodge was enjoying the peak of its cattle-town fame and prosperity as the quintessential frontier boom town, unrestrained by convention, the very embodiment of waywardness and wantonness. Few communities seemed more at odds with the national social values and mores that later generations would label Victorian. As a mecca for free-spending cowboys it was a place to let off steam, live high, and have fun. For the merchants, gamblers, joint operators, and cattlemen it was a time to fleece the unwary, reap handsome profits, and grow respectably rich.

A new look at the kinematics of the bulge from an N-body model

(Abridged) By using an N-body simulation of a bulge that was formed via a bar instability mechanism, we analyse the imprints of the initial (i.e. before bar formation) location of stars on the bulge kinematics, in particular on the heliocentric radial velocity distribution of bulge stars. Four different latitudes were considered: $b=-4^\circ$, $-6^\circ$, $-8^\circ$, and $-10^\circ$, along the bulge minor axis as well as outside it, at $l=\pm5^\circ$ and $l=\pm10^\circ$. The bulge X-shaped structure comprises stars that formed in the disk at different locations. Stars formed in the outer disk, beyond the end of the bar, which are part of the boxy peanut-bulge structure may show peaks in the velocity distributions at positive and negative heliocentric radial velocities with high absolute values that can be larger than 100 $\rm km$ $\rm s^{-1}$, depending on the observed direction. In some cases the structure of the velocity field is more complex and several peaks are observed. Stars formed in the inner disk, the most numerous, contribute predominantly to the X-shaped structure and present different kinematic characteristics. Our results may enable us to interpret the cold high-velocity peak observed in the APOGEE commissioning data, as well as the excess of high-velocity stars in the near and far arms of the X-shaped structure at $l$=$0^\circ$ and $b$=$-6^\circ$. When compared with real data, the kinematic picture becomes more complex due to the possible presence in the observed samples of classical bulge and/or thick disk stars. Overall, our results point to the existence of complex patterns and structures in the bulge velocity fields, which are generated by the bar. This suggests that caution should be used when interpreting the bulge kinematics: the presence of substructures, peaks and clumps in the velocity fields is not necessarily a sign of past accretion events.Comment: 21 pages, 18 figures. Accepted for publication in A&

A latest Cretaceous to earliest Paleogene dinoflagellate cyst zonation of Antarctica, and implications for phytoprovincialism in the high southern latitudes

The thickest uppermost Cretaceous to lowermost Paleogene (Maastrichtian to Danian) sedimentary succession in the world is exposed on southern Seymour Island (65° South) in the James Ross Basin, Antarctic Peninsula. This fossiliferous shallow marine sequence, which spans the Cretaceous–Paleogene boundary, has allowed a high-resolution analysis of well-preserved marine palynomorphs. Previous correlation of Cretaceous–Paleogene marine palynomorph assemblages in the south polar region relied on dinoflagellate cyst biozonations from New Zealand and southern Australia. The age model of the southern Seymour Island succession is refined and placed within the stratigraphical context of the mid to high southern palaeolatitudes. Quantitative palynological analysis of a new 1102 m continuous stratigraphical section comprising the uppermost Snow Hill Island Formation and the López de Bertodano Formation (Marambio Group) across southern Seymour Island was undertaken. We propose the first formal late Maastrichtian to early Danian dinoflagellate cyst zonation scheme for the Antarctic based on this exceptional succession. Two new late Maastrichtian zones, including three subzones, and one new early Danian zone are defined. The oldest beds correlate well with the late Maastrichtian of New Zealand. In a wider context, a new South Polar Province based on Maastrichtian to Danian dinoflagellate cysts is proposed, which excludes most southern South American marine palynofloras. This interpretation is supported by models of ocean currents around Antarctica and implies an unrestricted oceanic connection across Antarctica between southern South America and the Tasman Sea

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

Can reducing black carbon and methane below RCP2.6 levels keep global warming below 1.5C?

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordMethane and black carbon aerosols have been identified as exerting the two strongest positive radiative forcings after carbon dioxide and therefore drastic reductions in these atmospheric constituents could potentially offer strong leverage in reducing global warming. Using the HadGEM2-ES model we reduce concentrations of methane and black carbon while holding all other emissions at representative concentration pathway RCP2.6 levels to examine whether we can achieve the target of keeping global-mean temperature rise below 1.5 oC relative to the pre-industrial level during the remainder of the 21st century. We find that even total cessation of black carbon aerosol emissions is ineffective in attaining this goal. Reducing methane concentrations at four times the rate assumed in RCP2.6 is able to return warming levels to below 1.5 oC by the 2070s but overshoots the target level prior to that. As RCP2.6 represents an optimistic scenario relative to the Intended Nationally Determined Contributions our results highlight the importance of deep and rapid reductions in both CO2 and methane emissions if humanity is serious about attaining the 1.5 oC target.This work was supported by the Joint UK BEIS/Defra Met Office Hadley Centre Climate Programme (GA01101). CDJ was also supported by the European Union's Horizon 2020 research and innovation programme under grant agreement No 64181

On the kinematic deconvolution of the local neighbourhood luminosity function

A method for inverting the statistical star counts equation, including proper motions, is presented; in order to break the degeneracy in that equation it uses the supplementary constraints required by dynamical consistency. The inversion gives access to both the kinematics and the luminosity function of each population in three r\'egimes: the singular ellipsoid, the constant ratio Schwarzschild ellipsoid plane parallel models and the epicyclic model. This more realistic model is taylored to account for local neighbourhood density and velocity distribution. The first model is fully investigated both analytically and via means of a non-parametric inversion technique, while the second model is shown to be formally its equivalent. The effect of noise and incompleteness in apparent magnitude is investigated. The third model is investigated via a 5D+2D non-parametric inversion technique where positivity of the underlying luminosity function is explicitely accounted for. It is argued that its future application to data such as the Tycho catalogue (and in the upcoming satellite GAIA) could lead -- provided the vertical potential, and/or the asymmetric drift or w_0 are known -- to a non-parametric determination of the local neighbourhood luminosity function without any reference to stellar evolution tracks. It should also yield the proportion of stars for each kinematic component and a kinematic diagnostic to split the thin disk from the thick disk or the halo.Comment: 18 pages, LateX (or Latex, etc), mnras, accepted for publicatio