Far infrared observations of pre-protostellar sources in Lynds 183

Using ISOPHOT maps at 100 and 200um and raster scans at 100, 120, 150 and 200um we have detected four unresolved far-infrared sources in the high latitude molecular cloud L183. Two of the sources are identified with 1.3mm continuum sources found by Ward-Thompson et al. and are located near the temperature minimum and the coincident column density maximum of dust distribution. For these two sources, the ISO observations have enabled us to derive temperatures (about 8.3 K) and masses (about 1.4 and 2.4 solar masses). They are found to have masses greater than or comparable to their virial masses and are thus expected to undergo gravitational collapse. We classify them as pre-protostellar sources. The two new sources are good candidates for pre-protostellar sources or protostars within L183.Comment: 12 pages, 7 Postscript figures, 1 JPEG figure. Accepted for publication in Astronomy & Astrophysic

On the frequency of N2H+ and N2D+

Context : Dynamical studies of prestellar cores search for small velocity differences between different tracers. The highest radiation frequency precision is therefore required for each of these species. Aims : We want to adjust the frequency of the first three rotational transitions of N2H+ and N2D+ and extrapolate to the next three transitions. Methods : N2H+ and N2D+ are compared to NH3 the frequency of which is more accurately known and which has the advantage to be spatially coexistent with N2H+ and N2D+ in dark cloud cores. With lines among the narrowests, and N2H+ and NH3 emitting region among the largests, L183 is a good candidate to compare these species. Results : A correction of ~10 kHz for the N2H+ (J:1-0) transition has been found (~0.03 km/s) and similar corrections, from a few m/s up to ~0.05 km/s are reported for the other transitions (N2H+ J:3-2 and N2D+ J:1-0, J:2-1, and J:3-2) compared to previous astronomical determinations. Einstein spontaneous decay coefficients (Aul) are included

Far-infrared and molecular line observations of Lynds 183 - studies of cold gas and dust

We have mapped the dark cloud L183 in the far-infrared at 100um and 200um with the ISOPHOT photometer aboard the ISO satellite. The observations make it possible for the first time to study the properties of the large dust grains in L183 without confusion from smaller grains. The observations show clear colour temperature variations which are likely to be caused by changes in the emission properties of the dust particles. In the cloud core the far-infrared colour temperature drops below 12K. The data allow a new determination of the cloud mass and the mass distribution. The mass within a radius of 10 arcmin from the cloud centre is 25 Msun. We have mapped the cloud in several molecular lines including DCO+(2-1) and H13CO+(1-0). These species are believed to be tracers of cold and dense molecular material and we detect a strong anticorrelation between the DCO+ emission and the dust colour temperatures. In particular, the DCO+(2-1) emission is not detected towards the maximum of the 100um emission where the colour temperature rises above 15K. The H13CO+ emission follows the DCO+ distribution but CO isotopes show strong emission even towards the 100um peak. A comparison of the DCO+ and C18O maps shows sharp variations in the relative intensities of the species. Morphologically the 200um dust emission traces the distribution of dense molecular material as seen e.g. in C18O lines. A comparison with dust column density shows that C18O is depleted by a factor of 1.5 in the cloud core. We present results of R- and B-band starcounts. The extinction is much better correlated with the 200um than with the 100um emission. Based on the 200um correlation at low extinction values we deduce a value of ~17mag for the visual extinction towards the cloud centre.Comment: to be published in A&

An Evaluation of a District Level Professional Development Program for School Leaders

This study evaluated a district-based leadership institute for effectiveness of role transition for newly appointed administrators. The researcher used a non-experimental descriptive design utilizing a mixed-method approach of qualitative and quantitative data to evaluate the program. The population surveyed included a convenience sample of 23 administrators who participated in a district-based professional development program implemented for school leaders. A survey was devised based upon Georgia Leadership Institute for School Improvement (GLISI) and Human Capital Development & Education Leader Performance Support\u27s (H-ELPS), 8 Roles Assessment-District survey. The instrument focused on the key roles of school leaders used to distinguish the type of leadership skills one possesses including; the curriculum, assessment and instruction leader, data analysis leader, relationship leader, operational/process /process leader and the change leader. The study results from the data indicated the favorability and homogenous rating of the 6 leadership domains perceived by the respondents. These findings suggest that the perception of the Leaders Institute was overall effective for the participants in the district. Overwhelmingly most participants would be willing to continue employment in the district for 5 more years as a result of the program. Follow-up studies are advised to garner higher response rates to determine if the results are similar

Observations of chemical differentiation in clumpy molecular clouds

We have extensively mapped a sample of dense molecular clouds (L1512, TMC-1C, L1262, Per 7, L1389, L1251E) in lines of HC3N, CH3OH, SO and C^{18}O. We demonstrate that a high degree of chemical differentiation is present in all of the observed clouds. We analyse the molecular maps for each cloud, demonstrating a systematic chemical differentiation across the sample, which we relate to the evolutionary state of the cloud. We relate our observations to the cloud physical, kinematical and evolutionary properties, and also compare them to the predictions of simple chemical models. The implications of this work for understanding the origin of the clumpy structures and chemical differentiation observed in dense clouds are discussed.Comment: 20 pages, 7 figures. Higher quality figures appear in the published journal articl

Managerial behavior in fund tournaments—the impact of TrueSkill

Measuring mutual fund managers’ skills by Microsoft’s TrueSkill algorithm, we find highly skilled managers to behave self-confident resulting in higher risk-taking in the second half of the year compared to less skilled managers. Introducing the TrueSkill algorithm, which is widely used in the e-sports community, to this branch of literature, we can replicate previous findings and theories suggesting overconfidence for mid-years winners

Sulphur-bearing species in the star forming region L1689N

We report observations of the expected main S-bearing species (SO, SO2 and H2S) in the low-mass star forming region L1689N. We obtained large scale (~300''x200'') maps of several transitions from these molecules with the goal to study the sulphur chemistry, i.e. how the relative abundances change in the different physical conditions found in L1689N. We identified eight interesting regions, where we carried out a quantitative comparative study: the molecular cloud (as reference position), five shocked regions caused by the interaction of the molecular outflows with the cloud, and the two protostars IRAS16293-2422 and 16293E. In the cloud we carefully computed the gas temperature and density by means of a non-LTE LVG code, while in other regions we used previous results. We hence derived the column density of SO, SO2 and H2S, together with SiO and H2CO - which were observed previously - and their relevant abundance ratios. We find that SiO is the molecule that shows the largest abundance variations in the shocked regions, whereas S-bearing molecules show more moderate variations. Remarkably, the region of the brightest SiO emission in L1689N is undetected in SO2, H2S and H2CO and only marginally detected in SO. In the other weaker SiO shocks, SO2 is enhanced with respect to SO. We propose a schema in which the different molecular ratios correspond to different ages of the shocks. Finally, we find that SO, SO2 and H2S have significant abundance jumps in the inner hot core of IRAS16293-2422 and discuss the implications of the measured abundances.Comment: Accepted 08/10/0

Essays in Factor Investing

This thesis advances the theory and practice of factor investing by exploring the rich set of developed factors to explain portfolio performances in the equity and multi-asset space. Chapter 1 characterizes the strong performance of equal-weighted (EW) portfolios in relation to their value-weighted counterparts by utilizing various factor models. Unsurprisingly, EW investing comes with a highly significant positive size factor exposure but is also found to benefit from short-term reversal effects while suffering from negative momentum exposure due to its acyclic rebalancing character. Given that EW investing effectively emerges as factor investing in disguise, it seems natural to adopt a direct factor investing approach. To this end, the literature has proposed a multitude of firm characteristics for explaining the cross-section of stock returns, yet Chapter 2 demonstrates only about 15 factors to be relevant for spanning the entire factor zoo from an alpha perspective. Whilst these salient factors change through time, they fall into persistent factor style categories. Further broadening the scope, the thesis moves on to explain the cross-section of asset classes through a macro factor lens. Specifically, Chapter 3 investigates macroeconomic factor allocation based on macro factor-mimicking portfolios that consider style factors and individual asset classes alike. Chapter 4 investigates such macro factor investing over a century of data, demonstrating it to be robust in different economic regimes. Incorporating business cycle-based macro and style factor views in a Black-Litterman fashion we additionally accommodate the notion of factor timing to improve upon a diversified macro factor risk-parity strategy

Connecting Phenotype To Genotype: PheWAS-inspired Analysis Of Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is extremely heterogeneous clinically and genetically. There is a pressing need for a better understanding of the heterogeneity of ASD based on scientifically rigorous approaches centered on systematic evaluation of the clinical and research utility of both phenotype and genotype markers. This paper presents a holistic PheWAS-inspired method to identify meaningful associations between ASD phenotypes and genotypes. We generate two types of phenotype-phenotype (p-p) graphs: a direct graph that utilizes only phenotype data, and an indirect graph that incorporates genotype as well as phenotype data. We introduce a novel methodology for fusing the direct and indirect p-p networks in which the genotype data is incorporated into the phenotype data in varying degrees. The hypothesis is that the heterogeneity of ASD can be distinguished by clustering the p-p graph. The obtained graphs are clustered using network-oriented clustering techniques, and results are evaluated. The most promising clusterings are subsequently analyzed for biological and domain-based relevance. Clusters obtained delineated different aspects of ASD, including differentiating ASD-specific symptoms, cognitive, adaptive, language and communication functions, and behavioral problems. Some of the important genes associated with the clusters have previous known associations to ASD. We found that clusters based on integrated genetic and phenotype data were more effective at identifying relevant genes than clusters constructed from phenotype information alone. These genes included five with suggestive evidence of ASD association and one known to be a strong candidate

Managerial behavior in fund tournaments—the impact of TrueSkill

Measuring mutual fund managers’ skills by Microsoft’s TrueSkill algorithm, we find highly skilled managers to behave self-confident resulting in higher risk-taking in the second half of the year compared to less skilled managers. Introducing the TrueSkill algorithm, which is widely used in the e-sports community, to this branch of literature, we can replicate previous findings and theories suggesting overconfidence for mid-years winners