443 research outputs found
Neutron ages computed from experimental activation data
Computer program reduces time manually required to compute neutron age and to provide definite plan of procedural choices. Program allows convenient comparison of several fitting and error analysis procedures. Program code provides for error estimation of various integration options
A GLIMPSE into the Nature of Galactic Mid-IR Excesses
We investigate the nature of the mid-IR excess for 31 intermediate-mass stars
that exhibit an 8 micron excess in either the Galactic Legacy Infrared
Mid-Plane Survey Extraordinaire or the Mid-Course Space Experiment using high
resolution optical spectra to identify stars surrounded by warm circumstellar
dust. From these data we determine projected stellar rotational velocities and
estimate stellar effective temperatures for the sample. We estimate stellar
ages from these temperatures, parallactic distances, and evolutionary models.
Using MIPS [24] measurements and stellar parameters we determine the nature of
the infrared excess for 19 GLIMPSE stars. We find that 15 stars exhibit Halpha
emission and four exhibit Halpha absorption. Assuming that the mid-IR excesses
arise in circumstellar disks, we use the Halpha fluxes to model and estimate
the relative contributions of dust and free-free emission. Six stars exhibit
Halpha fluxes that imply free-free emission can plausibly explain the infrared
excess at [24]. These stars are candidate classical Be stars. Nine stars
exhibit Halpha emission, but their Halpha fluxes are insufficient to explain
the infrared excesses at [24], suggesting the presence of a circumstellar dust
component. After the removal of the free-free component in these sources, we
determine probable disk dust temperatures of Tdisk~300-800 K and fractional
infrared luminosities of L(IR)/L(*)~10^-3. These nine stars may be
pre-main-sequence stars with transitional disks undergoing disk clearing. Three
of the four sources showing Halpha absorption exhibit circumstellar disk
temperatures ~300-400 K, L(IR)/L(*)~10^-3, IR colors K-[24]< 3.3, and are warm
debris disk candidates. One of the four Halpha absorption sources has K-[24]>
3.3 implying an optically thick outer disk and is a transition disk candidate.Comment: 17 figures. Accepted for publication in Ap
The Blanco Cosmology Survey: Data Acquisition, Processing, Calibration, Quality Diagnostics and Data Release
The Blanco Cosmology Survey (BCS) is a 60 night imaging survey of 80
deg of the southern sky located in two fields: (,)= (5 hr,
) and (23 hr, ). The survey was carried out between
2005 and 2008 in bands with the Mosaic2 imager on the Blanco 4m
telescope. The primary aim of the BCS survey is to provide the data required to
optically confirm and measure photometric redshifts for Sunyaev-Zel'dovich
effect selected galaxy clusters from the South Pole Telescope and the Atacama
Cosmology Telescope. We process and calibrate the BCS data, carrying out PSF
corrected model fitting photometry for all detected objects. The median
10 galaxy (point source) depths over the survey in are
approximately 23.3 (23.9), 23.4 (24.0), 23.0 (23.6) and 21.3 (22.1),
respectively. The astrometric accuracy relative to the USNO-B survey is
milli-arcsec. We calibrate our absolute photometry using the stellar
locus in bands, and thus our absolute photometric scale derives from
2MASS which has % accuracy. The scatter of stars about the stellar locus
indicates a systematics floor in the relative stellar photometric scatter in
that is 1.9%, 2.2%, 2.7% and2.7%, respectively.
A simple cut in the AstrOmatic star-galaxy classifier {\tt spread\_model}
produces a star sample with good spatial uniformity. We use the resulting
photometric catalogs to calibrate photometric redshifts for the survey and
demonstrate scatter with an outlier fraction %
to . We highlight some selected science results to date and provide a
full description of the released data products.Comment: 23 pages, 23 figures . Response to referee comments. Paper accepted
for publication. BCS catalogs and images available for download from
http://www.usm.uni-muenchen.de/BC
Exposing the Contradictory Claims, Myths and Illusions of the “Secrets of Business Success and Company Longevity†Genre
Over the last three decades, several management consultants, academics and business practitioners have laid claim to identifying “the secrets†of business success and company longevity. However, a systematic analysis of 24 studies in this genre revealed fundamental disagreements over the elements these authors claim are the primary drivers of business performance and longevity, and demonstrates that they share eight methodological and analytical flaws. Furthermore, many of the claims they made about “the secrets†of business success have not stood the test of time. The paper explains why business practitioners will find little in these studies to help their companies become more successful now and in the future, and also speculates why several of these studies became international best-sellers during the 1980s, 1990s and 2000s. It concludes by suggesting some new avenues for future research in this domain, and highlights the practical implications of these findings for business practitioners
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Review Article: When 'life itself' goes to work: Reviewing shifts in organizational life through the lens of biopower
This review article suggests the English publication of Foucault’s lectures on biopower, The Birth of Biopolitics (2008), might be useful for extending our understandings of how organizational power relations have changed over the last 20 years. Unlike disciplinary power, which constrains and delimits individuals, the concept of biopower emphasizes how our life abilities and extra-work qualities (bios or ‘life itself’) are now key objects of exploitation – particularly under neoliberalism. The term biocracy is introduced to analyse recent reports on workplace experiences symptomatic of biopower. Finally, the conceptual weaknesses of biopower for organizational theorizing are critically evaluated to help develop the idea for future scholarship
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‘Being Yourself’ in the Electronic Sweatshop: New Forms of Normative Control
This article extends research about high-commitment management practices in tightly controlled work environments typified by the call centre. One promising research avenue suggests that normative management systems in such contexts, involving ‘fun’ exercises and culture programmes, etc., are more about distracting employee attention away from other, more taxing controls. This article develops such an approach by exploring the specific nature and conditions of such distraction. An empirical study of a call centre in which employees were encouraged to ‘just be themselves’ (in relation to lifestyle differences, sexuality, diverse identities, etc.) reveals how the distractions are partly informed by the dysfunctions of existing technical, bureaucratic and conventional cultural controls, all of which homogenize workers. Furthermore, the new regime not only serves to distract employees, but proves instrumental in capturing their sociality, energy and ‘authentic’ or ‘non-work’ personalities as emotional labour. At the same time, it gives rise to some contestation and less individualistic forms of authenticity. These outcomes have wider implications for our understanding of worker autonomy in and around hybrid control systems
Co-location as a catalyst for service innovation : a study of Scottish health and social care
Academic literature and policy on co-location of local public services focus on the cost benefits. Other benefits and outcomes of co-location, including service innovations benefiting users, are under-conceptualized. This paper suggests a framework for evaluating co-location as a learning environment for innovation, drawing on new case studies of five Community Health Partnerships in Scotland charged with more closely coordinating health and social care. We conclude that partnerships using co-location are benefiting from additional service innovations
A Multiwell Platform for Studying Stiffness-Dependent Cell Biology
Adherent cells are typically cultured on rigid substrates that are orders of magnitude stiffer than their tissue of origin. Here, we describe a method to rapidly fabricate 96 and 384 well platforms for routine screening of cells in tissue-relevant stiffness contexts. Briefly, polyacrylamide (PA) hydrogels are cast in glass-bottom plates, functionalized with collagen, and sterilized for cell culture. The Young's modulus of each substrate can be specified from 0.3 to 55 kPa, with collagen surface density held constant over the stiffness range. Using automated fluorescence microscopy, we captured the morphological variations of 7 cell types cultured across a physiological range of stiffness within a 384 well plate. We performed assays of cell number, proliferation, and apoptosis in 96 wells and resolved distinct profiles of cell growth as a function of stiffness among primary and immortalized cell lines. We found that the stiffness-dependent growth of normal human lung fibroblasts is largely invariant with collagen density, and that differences in their accumulation are amplified by increasing serum concentration. Further, we performed a screen of 18 bioactive small molecules and identified compounds with enhanced or reduced effects on soft versus rigid substrates, including blebbistatin, which abolished the suppression of lung fibroblast growth at 1 kPa. The ability to deploy PA gels in multiwell plates for high throughput analysis of cells in tissue-relevant environments opens new opportunities for the discovery of cellular responses that operate in specific stiffness regimes
Direct Interaction between Two Viral Proteins, the Nonstructural Protein 2CATPase and the Capsid Protein VP3, Is Required for Enterovirus Morphogenesis
In spite of decades-long studies, the mechanism of morphogenesis of plus-stranded RNA viruses belonging to the genus Enterovirus of Picornaviridae, including poliovirus (PV), is not understood. Numerous attempts to identify an RNA encapsidation signal have failed. Genetic studies, however, have implicated a role of the non-structural protein 2CATPase in the formation of poliovirus particles. Here we report a novel mechanism in which protein-protein interaction is sufficient to explain the specificity in PV encapsidation. Making use of a novel “reporter virus”, we show that a quasi-infectious chimera consisting of the capsid precursor of C-cluster coxsackie virus 20 (C-CAV20) and the nonstructural proteins of the closely related PV translated and replicated its genome with wild type kinetics, whereas encapsidation was blocked. On blind passages, encapsidation of the chimera was rescued by a single mutation either in capsid protein VP3 of CAV20 or in 2CATPase of PV. Whereas each of the single-mutation variants expressed severe proliferation phenotypes, engineering both mutations into the chimera yielded a virus encapsidating with wild type kinetics. Biochemical analyses provided strong evidence for a direct interaction between 2CATPase and VP3 of PV and CAV20. Chimeras of other C-CAVs (CAV20/CAV21 or CAV18/CAV20) were blocked in encapsidation (no virus after blind passages) but could be rescued if the capsid and 2CATPase coding regions originated from the same virus. Our novel mechanism explains the specificity of encapsidation without apparent involvement of an RNA signal by considering that (i) genome replication is known to be stringently linked to translation, (ii) morphogenesis is known to be stringently linked to genome replication, (iii) newly synthesized 2CATPase is an essential component of the replication complex, and (iv) 2CATPase has specific affinity to capsid protein(s). These conditions lead to morphogenesis at the site where newly synthesized genomes emerge from the replication complex
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