Angular Momentum Evolution of Stars in the Orion Nebula Cluster

(Abridged) We present theoretical models of stellar angular momentum evolution from the Orion Nebula Cluster (ONC) to the Pleiades and the Hyades. We demonstrate that observations of the Pleiades and Hyades place tight constraints on the angular momentum loss rate from stellar winds. The observed periods, masses and ages of ONC stars in the range 0.2--0.5 M$_\odot$, and the loss properties inferred from the Pleiades and Hyades stars, are then used to test the initial conditions for stellar evolution models. We use these models to estimate the distribution of rotational velocities for the ONC stars at the age of the Pleiades (120 Myr). The modeled ONC and observed Pleiades distributions of rotation rates are not consistent if only stellar winds are included. In order to reconcile the observed loss of angu lar momentum between these two clusters, an extrinsic loss mechanism such as protostar-accretion disk interaction is required. Our model, which evolves the ONC stars with a mass dependent saturation threshold normalized such that $\omega_{crit} = 5.4 \omega_\odot$ at 0.5 \m, and which includes a distribution of disk lifetimes that is uniform over the range 0--6 Myr, is consistent with the Pleiades. This model for disk-locking lifetimes is also consistent with inferred disk lifetimes from the percentage of stars with infrared excesses observed in young clusters. Different models, using a variety of initial period distributions and different maximum disk lifetimes, are also compared to the Pleiades. For disk-locking models that use a uniform distribution of disk lifetimes over the range 0 to $\tau_{max}$, the acceptable range of the maximum lifetime is $3.5 < \tau_{max} < 8.5$ Myr.Comment: 21 pages, 7 figures, submitted to Ap

OPTIMIZATION OF A BACK SURFACE CONTACT COPPER INDIUM GALLIUM SELENIDE (CIGS) THIN FILM SOLAR CELL WITH NEARLY ORTHOGONAL LATIN HYPERCUBE AND SILVACO

This thesis focuses on the optimization of a novel design back surface contact (BSC) copper indium gallium (di)selenide (CIGS). It introduces the Nearly Orthogonal Latin Hypercube (NOLH) design of experiments as a means of optimizing parameters to be entered into Silvaco ATLAS simulation software. By introducing a vertical p-n junction within the bulk of the solar cell the separation of charges was promoted, and with the BSC layout shadowing effects were negated. Due to these changes the optimized cell efficiency was found to be 27.1%, a relative increase of 11.5% from the previous optimal designs of prior theses. The NOLH generated data that could be run in parallel, significantly reducing simulation time, as well as giving a better understanding of the relationship between parameters within the solar cell. The NOLH design of experiments is the next step for all solar cell optimization efforts. The implications of the high-efficiency, lightweight design of the BSC CIGS solar cell ranges from terrestrial to celestial and everywhere in between. From lightweight comms recharge capabilities to unmanned aerial vehicle (UAV) power sources, and even satellites, the potential for CIGS are endless.Lieutenant, United States NavyApproved for public release. Distribution is unlimited

Blind fluorescence structured illumination microscopy: A new reconstruction strategy

In this communication, a fast reconstruction algorithm is proposed for fluorescence \textit{blind} structured illumination microscopy (SIM) under the sample positivity constraint. This new algorithm is by far simpler and faster than existing solutions, paving the way to 3D and/or real-time 2D reconstruction.Comment: submitted to IEEE ICIP 201

Understanding Policy Change through Bricolage: The Case of Chile's Renewable Energy Policy

Chile is a country where path dependency made energy policy change extremely difficult by international standards. However, the country has recently become a renewable energy poster child thanks to a gradual process of policy change. How was this possible? This article contributes to discussions about policy change driven by ideas and to explaining the puzzling case of Chilean energy policy change. It does so by discussing the mechanism of bricolage—the recombination of old and new ideas by policy entrepreneurs—and its capacity to produce policy change in contexts of high path dependency. The article develops the political manifestations and consequences of bricolage and problematizes how actors continue to contest and change ideas' meaning after they have been institutionalized, a key question when analyzing processes of bricolage. The analysis is based on an array of data sources including interviews with key actors, newspaper notes, and legislative proceedings.1 Introduction 2 Literature review 3 Chile: A least-likely case of energy policy change 4 Methods, data, and analysis 5 Results: Explaining the change in Chilean energy policy 6 Conclusions and discussion Acknowledgements Appendix A Reference

Alien Registration- Savoie, Mary A (Bath, Sagadahoc County)

https://digitalmaine.com/alien_docs/8803/thumbnail.jp

The Origin of Enhanced Activity in the Suns of M67

We report the results of the analysis of high resolution photospheric line spectra obtained with the UVES instrument on the VLT for a sample of 15 solar-type stars selected from a recent survey of the distribution of H and K chromospheric line strengths in the solar-age open cluster M67. We find upper limits to the projected rotation velocities that are consistent with solar-like rotation (i.e., v sini ~< 2-3 km/s) for objects with Ca II chromospheric activity within the range of the contemporary solar cycle. Two solar-type stars in our sample exhibit chromospheric emission well in excess of even solar maximum values. In one case, Sanders 1452, we measure a minimum rotational velocity of vsini = 4 +/- 0.5 km/s, or over twice the solar equatorial rotational velocity. The other star with enhanced activity, Sanders 747, is a spectroscopic binary. We conclude that high activity in solar-type stars in M67 that exceeds solar levels is likely due to more rapid rotation rather than an excursion in solar-like activity cycles to unusually high levels. We estimate an upper limit of 0.2% for the range of brightness changes occurring as a result of chromospheric activity in solar-type stars and, by inference, in the Sun itself. We discuss possible implications for our understanding of angular momentum evolution in solar-type stars, and we tentatively attribute the rapid rotation in Sanders 1452 to a reduced braking efficiency.Comment: accepted by Ap

Internal Dust Correction Factors for Star Formation Rates Derived for Dusty \HII Regions and Starburst Galaxies

Star formation rates in galaxies are frequently estimated using the Balmer line fluxes. However, these can be systematically underestimated because dust competes for the absorption of Lyman continuum photons in the ionized gas. Here we present theoretical correction factors in a simple analytic form. T These factors scale as the product of the ionization parameter, ${\cal U}$, and the nebular O/H abundance ratio, both of which can now be derived from the observation of bright nebular line ratios. The correction factors are only somewhat dependent upon the photoelectron production by grains, but are very sensitive to the presence of complex PAH-like carbonaceous molecules in the ionized gas, providing that these can survive in such an environment.Comment: 13 pages, 1 figures, Accepted for publication in ApJ. (Feb 1, 2003

Speaking Welcome: A Discursive Analysis of an Immigrant Mentorship Event in Atlantic Canada

This article offers an analysis of a business mentorship event in Fredericton, NB, which targeted immigrants sponsored through the New Brunswick Provincial Nominee Program (NBPNP)—an economic revitalization program designed to attract foreign business people and skilled workers to settle in the province. Applying Derrida’s concept of hospitality as a technology of whiteness, we examine the stated and implicitly understood expectations for the NBPNP, including the mechanisms at play for regulating newcomer’s behavior and comportment. We locate our analysis in the context of a regionally expressed Canadian multiculturalism, extending the relevance of our findings beyond Fredericton to Atlantic Canada. We ask: how do associated discourses of whiteness, multiculturalism and hospitality come into play to shape dynamics of power existing between hosts (settlement workers, various shadow state actors and mentor volunteers) and racialized newcomer guests? As a racialized threshold event, the Sip, Greet and Meet facilitated an exchange of hospitality such that the New Brunswick native hosts marked newcomers as perpetual arrivants, while holding the immigrants responsible for the success of their settlement in the Fredericton region. We show how the discourses regarding newcomers’ duties cleared nativist inhabitants of any accountability for the success of immigrant settlement. We also show how the process of welcoming conveyed a message that the future success of the local community, the province and even Atlantic Canada depended on the business class immigrants’ ability to serve as dutiful and grateful guests

Governance gaps in eradicating forced labor: from global to domestic supply chains

A growing body of scholarship analyzes the emergence and resilience of forced labor in developing countries within global value chains (GVCs). However, little is known about how forced labor arises within domestic supply chains concentrated within national borders, producing products for domestic consumption. We conduct one of the first studies of forced labor in domestic supply chains, through a cross-industry comparison of the regulatory gaps surrounding forced labor in the United Kingdom. We find that understanding the dynamics of forced labor in domestic supply chains requires us to conceptually modify the GVC framework to understand similarities and differences across these contexts. We conclude that addressing the governance gaps that surround forced labor will require scholars and policymakers to carefully refine their thinking about how we might design operative governance that effectively engages with local variation

The Angular Momentum Evolution of 0.1-10 Msun Stars From the Birthline to the Main Sequence

(Abridged) Projected rotational velocities (vsini) have been measured for a sample of 145 stars with masses between 0.4 and >10 Msun (median mass 2.1 Msun) located in the Orion star-forming complex. These measurements have been supplemented with data from the literature for Orion stars with masses as low as 0.1 Msun. The primary finding from analysis of these data is that the upper envelope of the observed values of angular momentum per unit mass (J/M) varies as M^0.25 for stars on convective tracks having masses in the range ~0.1 to ~3 Msun. This power law extends smoothly into the domain of more massive stars (3 to 10 Msun), which in Orion are already on the ZAMS. This result stands in sharp contrast to the properties of main sequence stars, which show a break in the power law and a sharp decline in J/M with decreasing mass for stars with M <2 Msun. A second result of our study is that this break is seen already among the PMS stars in our Orion sample that are on radiative tracks, even though these stars are only a few million years old. A comparison of rotation rates seen for stars on either side of the convective-radiative boundary shows that stars do not rotate as solid bodies during the transition from convective to radiative tracks.Comment: to appear in Ap