1,026 research outputs found
The Search For A Dog-Free Portfolio: Why Unions Matter To Investors
This paper uses portfolio filtering and weighting research to create a dog-free portfolio. The variables used to create the dog-free portfolio include level of unionization and book-to-market. The filtered and weighted portfolio is averaging 47 basis points alpha per month from 1991-2007 over the benchmark S&P500, outperforming in 60.8% of the months. Using annual data, the portfolio averages 603 basis points alpha from 1991-2007 over the benchmark S&P500, outperforming 82.4% of the time. 
Computational Thinking Integration into Middle Grades Science Classrooms: Strategies for Meeting the Challenges
This paper reports findings from the efforts of a university-based research team as they worked with middle school educators within formal school structures to infuse computer science principles and computational thinking practices. Despite the need to integrate these skills within regular classroom practices to allow all students the opportunity to learn these essential 21st Century skills, prior practice has been to offer these learning experiences outside of mainstream curricula where only a subset of students have access. We have sought to leverage elements of the research-practice partnership framework to achieve our project objectives of integrating computer science and computational thinking within middle science classrooms. Utilizing a qualitative approach to inquiry, we present narratives from three case schools, report on themes across work sites, and share recommendations to guide other practitioners and researchers who are looking to engage in technology-related initiatives to impact the lives of middle grades students
An Evaluation of the Fluctuations in New Car Sales for Rapid City, Denver, and the U.S. from October 1973 Through March 1975
During the past three years the American economy in general and the automobile industry in particular was plagued with inflation, recession, and unemployment. With sales declining during those years, profits vanished and layoffs increased within the automobile industry. One of the factors that contributed to this problem was the Arab oil Embargo of November, 1973. In the last quarter of 1973, when the automobile industry started its prolonged decline in sales, most of the Oil Producing and Export Countries (OPEC) were redirecting the world economy for their own benefit through embargoes and price fixing on their oil. Because of the dramatic ramifications the Arab Oil Embargo had on the U.S. automobile industry, this study focuses on the changes in consumer demand for automobiles during the embargo of November, 1973, and the recession and inflationary period that follower through the first quarter of 1975. The event that took place in the automobile industry during those periods are outlined below
Eligibility of patients with advanced non-small cell lung cancer for phase III chemotherapy trials
<p>Abstract</p> <p>Background</p> <p>Evidence that chemotherapy improves survival and quality of life in patients with stage IIIB & IV non small cell lung cancer (NSCLC) is based on large randomized controlled trials. The purpose of this study was to determine eligibility of patients with advanced NSCLC for major chemotherapy trials.</p> <p>Methods</p> <p>Physicians treating stage IIIB/IV NSCLC at Sydney Cancer Centre assessed patient eligibility for the E1594, SWOG9509 and TAX326 trials for patients presenting from October 2001 to December 2002. A review of the centre's registry was used to obtain missing data.</p> <p>Results</p> <p>199 patients with advanced NSCLC were registered during the 14-month period. Characteristics of 100 patients were defined prospectively, 85 retrospectively: 77% males, median age 68 (range 32â88), 64% stage IV disease. Only 35% met trial eligibility for E1594 and 28% for SWOG9509 and TAX326. Common reasons for ineligibility were: co-morbidities 75(40%); ECOG Performance Status â„2 72(39%); symptomatic brain metastasis 15(8%); and previous cancers 21(11%). Many patients were ineligible by more than one criterion.</p> <p>Conclusion</p> <p>The majority of patients with advanced NSCLC were ineligible for the large chemotherapy trials. The applicability of trial results to advanced lung cancer populations may be limited. Future trials should be conducted in a more representative population.</p
The ACS Nearby Galaxy Survey Treasury IX. Constraining asymptotic giant branch evolution with old metal-poor galaxies
In an attempt to constrain evolutionary models of the asymptotic giant branch
(AGB) phase at the limit of low masses and low metallicities, we have examined
the luminosity functions and number ratio between AGB and red giant branch
(RGB) stars from a sample of resolved galaxies from the ACS Nearby Galaxy
Survey Treasury (ANGST). This database provides HST optical photometry together
with maps of completeness, photometric errors, and star formation histories for
dozens of galaxies within 4 Mpc. We select 12 galaxies characterized by
predominantly metal-poor populations as indicated by a very steep and blue RGB,
and which do not present any indication of recent star formation in their
color--magnitude diagrams. Thousands of AGB stars brighter than the tip of the
RGB (TRGB) are present in the sample (between 60 and 400 per galaxy), hence the
Poisson noise has little impact in our measurements of the AGB/RGB ratio. We
model the photometric data with a few sets of thermally pulsing AGB (TP-AGB)
evolutionary models with different prescriptions for the mass loss. This
technique allows us to set stringent constraints to the TP-AGB models of
low-mass metal-poor stars (with M<1.5 Msun, [Fe/H]<~-1.0). Indeed, those which
satisfactorily reproduce the observed AGB/RGB ratios have TP-AGB lifetimes
between 1.2 and 1.8 Myr, and finish their nuclear burning lives with masses
between 0.51 and 0.55 Msun. This is also in good agreement with recent
observations of white dwarf masses in the M4 old globular cluster. These
constraints can be added to those already derived from Magellanic Cloud star
clusters as important mileposts in the arduous process of calibrating AGB
evolutionary models.Comment: To appear in ApJ, a version with better resolution is in
http://stev.oapd.inaf.it/~lgirardi/rgbagb.pd
The Contribution of TP-AGB and RHeB Stars to the Near-IR Luminosity of Local Galaxies: Implications for Stellar Mass Measurements of High Redshift Galaxies
Using high spatial resolution HST WFC3 and ACS imaging of resolved stellar
populations, we constrain the contribution of thermally-pulsing asymptotic
giant branch (TP-AGB) stars and red helium burning (RHeB) stars to the 1.6 um
near-infrared (NIR) luminosities of 23 nearby galaxies. The TP-AGB phase
contributes as much as 17% of the integrated F160W flux, even when the red
giant branch is well populated. The RHeB population contribution can match or
even exceed the TP-AGB contribution, providing as much as 21% of the integrated
F160W light. The NIR mass-to-light (M/L) ratio should therefore be expected to
vary significantly due to fluctuations in the star formation rate over
timescales from 25 Myr to several Gyr. We compare our observational results to
predictions based on optically derived star formation histories and stellar
population synthesis (SPS) models, including models based on the Padova
isochrones (used in popular SPS programs). The SPS models generally reproduce
the expected numbers of TP-AGB stars in the sample. The same SPS models,
however, give a larger discrepancy in the F160W flux contribution from the
TP-AGB stars, over-predicting the flux by a weighted mean factor of 2.3 +/-0.8.
This larger offset is driven by the prediction of modest numbers of high
luminosity TP-AGB stars at young (<300 Myrs) ages. The best-fit SPS models
simultaneously tend to under-predict the numbers and fluxes of stars on the
RHeB sequence, typically by a factor of 2.0+/-0.6 for galaxies with significant
numbers of RHeBs. Coincidentally, over-prediction of the TP-AGB and
under-prediction of the RHeBs result in a NIR M/L ratio largely unchanged for a
rapid star formation rate. However, the NIR-to-optical flux ratio of galaxies
could be significantly smaller than AGB-rich models would predict, an outcome
that has been observed in some intermediate redshift post-starburst galaxies.
(Abridged)Comment: 28 Pages, 12 Figures, 5 Tables, Accepted for Publication in the
Astrophysical Journa
Resolved Near-infrared Stellar Populations in Nearby Galaxies
We present near-infrared (NIR) color-magnitude diagrams (CMDs) for the resolved stellar populations within 26 fields of 23 nearby galaxies (âČ 4 Mpc), based on images in the F110W and F160W filters taken with the Wide-Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). The CMDs are measured in regions spanning a wide range of star formation histories, including both old dormant and young star-forming populations. We match key NIR CMD features with their counterparts in more familiar optical CMDs, and identify the red core helium-burning (RHeB) sequence as a significant contributor to the NIR flux in stellar populations younger than a few 100 Myr old. The strength of this feature suggests that the NIR mass-to-light ratio can vary significantly on short timescales in star-forming systems. The NIR luminosity of star-forming galaxies is therefore not necessarily proportional to the stellar mass. We note that these individual RHeB stars may also be misidentified as old stellar clusters in images of nearby galaxies. For older stellar populations, we discuss the CMD location of asymptotic giant branch (AGB) stars in the HST filter set and explore the separation of AGB subpopulations using a combination of optical and NIR colors. We empirically calibrate the magnitude of the NIR tip of the red giant branch in F160W as a function of color, allowing future observations in this widely adopted filter set to be used for distance measurements. We also analyze the properties of the NIR red giant branch (RGB) as a function of metallicity, showing a clear trend between NIR RGB color and metallicity. However, based on the current study, it appears unlikely that the slope of the NIR RGB can be used as an effective metallicity indicator in extragalactic systems with comparable data. Finally, we highlight issues with scattered light in the WFC3, which becomes significant for exposures taken close to a bright Earth limb
VZV in biopsy-positive and -negative giant cell arteritis: Analysis of 100+ temporal arteries
Objective:
Varicella-zoster virus (VZV) infection may trigger the inflammatory cascade that characterizes giant cell arteritis (GCA).
Methods:
Formalin-fixed, paraffin-embedded GCA-positive temporal artery (TA) biopsies (50 sections/TA) including adjacent skeletal muscle and normal TAs obtained postmortem from subjects >50 years of age were examined by immunohistochemistry for presence and distribution of VZV antigen and by ultrastructural examination for virions. Adjacent regions were examined by hematoxylin & eosin staining. VZV antigenĂąâŹâpositive slides were analyzed by PCR for VZV DNA.
Results:
VZV antigen was found in 61/82 (74%) GCA-positive TAs compared with 1/13 (8%) normal TAs (p < 0.0001, relative risk 9.67, 95% confidence interval 1.46, 63.69). Most GCA-positive TAs contained viral antigen in skip areas. VZV antigen was present mostly in adventitia, followed by media and intima. VZV antigen was found in 12/32 (38%) skeletal muscles adjacent to VZV antigenĂąâŹâpositive TAs. Despite formalin fixation, VZV DNA was detected in 18/45 (40%) GCA-positive VZV antigenĂąâŹâpositive TAs, in 6/10 (60%) VZV antigenĂąâŹâpositive skeletal muscles, and in one VZV antigenĂąâŹâpositive normal TA. Varicella-zoster virions were found in a GCA-positive TA. In sections adjacent to those containing VZV, GCA pathology was seen in 89% of GCA-positive TAs but in none of 18 adjacent sections from normal TAs.
Conclusions:
Most GCA-positive TAs contained VZV in skip areas that correlated with adjacent GCA pathology, supporting the hypothesis that VZV triggers GCA immunopathology. Antiviral treatment may confer additional benefit to patients with GCA treated with corticosteroids, although the optimal antiviral regimen remains to be determined
Evolution of Thermally Pulsing Asymptotic Giant Branch Stars. IV. Constraining Mass Loss and Lifetimes of Low Mass, Low Metallicity AGB Stars
The evolution and lifetimes of thermally pulsating asymptotic giant branch (TP-AGB) stars suffer from significant uncertainties. In this work, we analyze the numbers and luminosity functions of TP-AGB stars in six quiescent, low metallicity ([Fe/H] 72 -0.86) galaxies taken from the ACS Nearby Galaxy Survey Treasury sample, using Hubble Space Telescope (HST) photometry in both optical and near-infrared filters. The galaxies contain over 1000 TP-AGB stars (at least 60 per field). We compare the observed TP-AGB luminosity functions and relative numbers of TP-AGB and red giant branch (RGB) stars, N TP-AGB/N RGB, to models generated from different suites of TP-AGB evolutionary tracks after adopting star formation histories derived from the HST deep optical observations. We test various mass-loss prescriptions that differ in their treatments of mass loss before the onset of dust-driven winds (pre-dust). These comparisons confirm that pre-dust mass loss is important, since models that neglect pre-dust mass loss fail to explain the observed N TP-AGB/N RGB ratio or the luminosity functions. In contrast, models with more efficient pre-dust mass loss produce results consistent with observations. We find that for [Fe/H] 72 -0.86, lower mass TP-AGB stars (M 72 1 M ) must have lifetimes of 3c0.5 Myr and higher masses (M 72 3 M ) must have lifetimes 72 1.2 Myr. In addition, assuming our best-fitting mass-loss prescription, we show that the third dredge-up has no significant effect on TP-AGB lifetimes in this mass and metallicity range. \ua9 2014. The American Astronomical Society. All rights reserved.
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