Stellar Populations and Ages of M82 Super Star Clusters

We present high signal-to-noise optical spectra of two luminous super star clusters in the starburst galaxy M82. The data for cluster F and the nearby, highly reddened cluster L were obtained with the William Herschel Telescope (WHT) at a resolution of 1.6A. The blue spectrum (3250-5540A) of cluster F shows features typical of mid-B stars. The red spectra (5730-8790A) of clusters F and L show the Ca II triplet and numerous F and G-type absorption features. Strong Ca II and Na I interstellar absorption lines arising in M82 are also detected, and the 6283A diffuse interstellar band appears to be present. The quality of the WHT spectra allows us to considerably improve previous age estimates for cluster F. By comparing the blue spectrum with theoretical model cluster spectra using the PEGASE spectral synthesis code (Fioc & Rocca-Volmerange 1997), we derive an age of 60+/-20 Myr. The strength of the Ca II triplet is also in accord with this age. Cluster L appears to have a similar age, although this is much less certain. The measured radial velocities for the two clusters differ substantially, indicating that they are located in different regions of the M82 disk. Cluster F appears to be deep in M82, slightly beyond the main starburst region while the highly obscured cluster L lies near the outer edges of the disk. We derive an absolute V magnitude of -16.5 for F indicating that it is an extremely massive cluster. The presence of such a luminous super star cluster suggests that the M82 starburst experienced an episode of intense star formation approximately 60 Myr ago.Comment: 10 pages and 5 figures for publication in MNRA

Carbon changes in conterminous US forests associated with growth and major disturbances.

Abstract We estimated forest area and carbon changes in the conterminous United States using a remote sensing based land cover change map, forest fire data from the Monitoring Trends in Burn Severity program, and forest growth and harvest data from the USDA Forest Service, Forest Inventory and Analysis Program. Natural and human-associated disturbances reduced the forest ecosystems\u27 carbon sink by 36% from 1992 to 2001, compared to that without disturbances in the 48 states. Among the three identified disturbances, forest-related land cover change contributed 33% of the total effect in reducing the forest carbon potential sink, while harvests and fires accounted for 63% and 4% of the total effect, respectively. The nation\u27s forests sequestered 1.6 ± 0.1Pg (1015 petagram) carbon during the period, or 0.18PgCyr-1, with substantial regional variation. The southern region of the United States was a small net carbon source whereas the greater Pacific Northwest region was a strong net sink. Results of the approach fit reasonably well at an aggregate level with other related estimates of the current forest US greenhouse gas inventory, suggesting that further research using this approach is warranted

Investment Decisions by Individuals and Groups in \u27Sunk Cost\u27 Situations: The Potential Impact of Shared Representations

Past research has shown that individuals prefer to continue investing resources into a failing endeavor once a considerable investment has been made, even when abandoning the project would be more rational economically. This phenomenon has been labeled the sunk cost effect (Arkes & Blumer, 1985). Since investment decisions are often made by groups, we compared individual and group propensities for falling prey to the sunk cost effect. we also varied whether or not individuals and groups needed to justify their investment decision to a superior. Both individuals and groups showed the sunk cost effect. Group process analyses showed that error-prone majorities were more powerful than more rational minorities. In addition, group decisions seemed to be a function of two competing task representations--one favoring the sunk cost interpretation and the other favoring economic rationality

A Bis-Urea Naphthalene Macrocycle Displaying Two Crystal Structures with Parallel Ureas

Herein we synthesized a bis-urea macrocycle from 2,7-dimethylnaphthalene that displays an unusual parallel urea conformation. The naphthalenes also adopt a bowl shape over the anticipated parallel planar orientation. Crystallization of the macrocycle from different solvent systems affords two solvated forms. 1·DMSO·(H2O)2 has an extended columnar structure where parallel macrocycles are linked by intervening hydrogen bonded water molecules. In 1·(MeOH)2direct hydrogen-bonds link the macrocycles into chains, which hydrogen-bond with methanolmolecules to form a layered structure

Sizes and Shapes of Young Star Cluster Light Profiles in M83

We measure the radii and two-dimensional light profiles of a large sample of young, massive star clusters in M83 using archival HST/WFC3 imaging of seven adjacent fields. We use GALFIT to fit the two-dimensional light profiles of the clusters, from which we find effective (half-light) radii, core radii, and slopes of the power-law (EFF) profile ($\eta$). We find lognormal distributions of effective radius and core radius, with medians of $\approx$2.5 pc and $\approx$1.3 pc, respectively. Our results provide strong evidence for a characteristic size of young, massive clusters. The average effective radius and core radius increase somewhat with cluster age. Little to no change in effective radius is observed with increasing galactocentric distance, except perhaps for clusters younger than 100 Myr. We find a shallow correlation between effective radius and mass for the full cluster sample, but a stronger correlation is present for clusters 200-300 Myr in age. Finally, the majority of the clusters are best fit by an EFF model with index $\eta\leq3.0$. There is no strong evidence for change in $\eta$ with cluster age, mass, or galactocentric distance. Our results suggest that clusters emerge from early evolution with similar radii and are not strongly affected by the tidal field of M83. Mass loss due to stellar evolution and/or GMC interactions appear to dominate cluster expansion in the age range we study.Comment: 34 pages, 11 figures, 3 tables, accepted by MNRAS. Machine-readable table attached (full version of Table 3). To obtain, download the source file from the "Other formats" link abov

Does woman + a network = career progression?

Question: I am an ambitious and talented junior manager who has recently been hired by FAB plc, a large multinational company. I am also a woman and, as part of my induction pack, have received an invitation to join FABFemmes - the in-company women's network. I don't think my gender has been an obstacle to my success thus far and so I don't really feel the need to join. But on the other hand I don't want to turn my back on something that might offer me a useful source of contacts to help me advance up the career ladder. What would be the best thing to do? - Ms Ambitious, UK

Psychosocial Interventions Delivered by Primary Care Physicians to Patients with Depression

Few high-quality studies have been conducted examining the effectiveness of psychosocial interventions performed by primary care physicians for patients with major depression. Two randomized controlled clinical trials (RCTs) found that a psychosocial intervention, specifically problem-solving therapy, is as effective as pharmacotherapy for symptoms of major depression. (Strength of recommendation: B) However, these results should be interpreted with some degree of caution because of the limited number of studies and their small sample size

Randomized Algorithms Considered Harmful

Recent advances in distributed communication and omniscient algorithms cooperate in order to achieve operating systems. Given the current status of relational information, cyberinformaticians dubiously desire the visualization of randomized algorithms, which embodies the confirmed principles of loss-less software engineering. We argue that the lookaside buffer can be made pseudorandom, “smart”, and client-server