1,182 research outputs found
Impact of Operational Planning on Small Business Retail Performance
This study examined operational planning activities (inventory, marketing, financial, and personnel) of successful (n=92) and failed (n= 91) small business apparel and accessory retailers. Results suggest that inventory, marketing, and financial planning activities significantly differed between groups with successful retailers being more likely than failed retailers to engage in such functions. No differences were found between groups in personnel planning. Study implications are discussed for small business practitioners and academic researchers
Succinate dehydrogenase (SDH)-deficient renal carcinoma:a morphologically distinct entity: a clinicopathologic series of 36 tumors from 27 patients
Succinate dehydrogenase (SDH)-deficient renal carcinoma has been accepted as a provisional entity in the 2013 International Society of Urological Pathology Vancouver Classification. To further define its morphologic and clinical features, we studied a multi-institutional cohort of 36 SDH-deficient renal carcinomas from 27 patients, including 21 previously unreported cases. We estimate that 0.05% to 0.2% of all renal carcinomas are SDH deficient. Mean patient age at presentation was 37 years (range, 14 to 76 y), with a slight male predominance (M:F=1.7:1). Bilateral tumors were observed in 26% of patients. Thirty-four (94%) tumors demonstrated the previously reported morphology at least focally, which included: solid or focally cystic growth, uniform cytology with eosinophilic flocculent cytoplasm, intracytoplasmic vacuolations and inclusions, and round to oval low-grade nuclei. All 17 patients who underwent genetic testing for mutation in the SDH subunits demonstrated germline mutations (16 in SDHB and 1 in SDHC). Nine of 27 (33%) patients developed metastatic disease, 2 of them after prolonged follow-up (5.5 and 30 y). Seven of 10 patients (70%) with high-grade nuclei metastasized as did all 4 patients with coagulative necrosis. Two of 17 (12%) patients with low-grade nuclei metastasized, and both had unbiopsied contralateral tumors, which may have been the origin of the metastatic disease. In conclusion, SDH-deficient renal carcinoma is a rare and unique type of renal carcinoma, exhibiting stereotypical morphologic features in the great majority of cases and showing a strong relationship with SDH germline mutation. Although this tumor may undergo dedifferentiation and metastasize, sometimes after a prolonged delay, metastatic disease is rare in the absence of high-grade nuclear atypia or coagulative necrosis
The 1996 Soft State Transitions of Cygnus X-1
We report continuous monitoring of Cygnus X-1 in the 1.3 to 200 keV band
using ASM/RXTE and BATSE/CGRO for about 200 days from 1996 February 21 to 1996
early September. During this period Cygnus X-1 experienced a hard-to-soft and
then a soft-to-hard state transition. The low-energy X-ray (1.3-12 keV) and
high-energy X-ray (20-200 keV) fluxes are strongly anti-correlated during this
period. During the state transitions flux variations of about a factor of 5 and
15 were seen in the 1.3-3.0 keV and 100-200 keV bands, respectively, while the
average 4.8-12 keV flux remains almost unchanged. The net effect of this
pivoting is that the total 1.3-200 keV luminosity remained unchanged to within
about 15%. The bolometric luminosity in the soft state may be as high as 50-70%
above the hard state luminosity, after color corrections for the luminosity
below 1.3 keV. The blackbody component flux and temperature increase in the
soft state is probably caused by a combination of the optically thick disk mass
accretion rate increase and a decrease of the inner disk radius.Comment: 18 pages, 1 PostScript figure. Accepted for ApJ
The Off State of GX 339-4
We report BeppoSAX and optical observations of the black hole candidate GX
339-4 during its X-ray `off' state in 1999. The broad-band (0.8-50 keV) X-ray
emission can be fitted by a single power law with spectral index, \alpha ~1.6.
The observed luminosity is 6.6e33 erg s^{-1} in the 0.5-10 keV band, which is
at the higher end of the flux distribution of black hole soft X-ray transients
in quiescence, comparable to that seen in GS 2023+338 and 4U 1630-47. An
optical observation just before the BeppoSAX observation shows the source to be
very faint at these wavelengths as well (B=20.1, V=19.2). By comparing with
previously reported `off' and low states (LS), we conclude that the `off' state
is actually an extension of the LS, i.e. a LS at lower intensities. We propose
that accretion models such as the advection-dominated accretion flows are able
to explain the observed properties in such a state.Comment: Accepted for publication in MNRA
From Bibliophile to Sesquipedalian: Modeling the Role of Reading Experience in Vocabulary and Reading Comprehension
Purpose We investigated the roles of leisure reading and word reading ability in vocabulary and reading comprehension development in 598 adolescents at ages 10, 11, and 12 (285 girls, 313 boys). Method Structural equation modeling was used to test whether word reading was associated with vocabulary and reading comprehension: a) directly; b) indirectly via leisure reading; or c) both. Results We found both direct and indirect effects of word reading on vocabulary: word reading ability directly predicted outcomes, and also predicted the amount of leisure reading, which in turn predicted vocabulary. For reading comprehension we observed direct but not indirect effects of word reading. As expected, vocabulary and reading comprehension outcomes were strongly correlated. Conclusion Our findings demonstrate the direct effect of word reading ability in predicting vocabulary and reading comprehension, and reveal a crucial mediating role of leisure reading in the development of vocabulary
A0620-00 revisited: a black-hole transient case-study
For the first time we have performed a detailed study of the X-ray, optical
and infra-red light curves of the 1975/1976 outburst of the famous black-hole
transient A0620-00 (Nova Mon 1975, V616 Mon). During the various stages of its
outburst the X-rays lag the optical by ~5-20 days. Moreover, the activity
associated with the secondary maximum started even earlier in the infra-red.
This suggests that most of the outburst processes occur in the outer parts of
the disk. We also find various drops in the X-ray intensity (lasting ~1 day or
more). Near one of these a local maximum in the optical light curve occurs.
This maximum appears ~30 days after the secondary maximum, i.e. close to the
viscous time scale of an irradiated disk. We suggest this feature to be an
`echo' of the secondary maximum. At the end of the outburst a similar local
optical maximum occurs, which might be an `echo' of the tertiary maximum. We
find that the drops in the optical and X-rays near the tertiary maximum are
also present in other SXTs. They always occur ~150 days after the start of the
outburst. We find for the first time that the X-ray spectrum of A0620-00 starts
to harden ~100-150 days after the start of its outburst, similar to GS2000+25
and GS1124-68. This suggests we witness the transition from the so-called high
to low state at that time. We show that the optical outburst light curve of
A0620-00 closely resembles that of the cataclysmic variable AL Com. This
strengthens the similarity in the properties of the SXTs and TOADs (or WZ Sge
stars), and shows that the optical outburst light curves of both groups are
governed by the disk properties and not by the compact object. Since
irradiation provides a natural mechanism to prolong the outburst of SXTs, we
suggest this could be of influence as well during TOAD outbursts.Comment: 38 pages, 10 figures, accepted for New Astronomy Review
Infrared Spectroscopy of Symbiotic Stars. IV. V2116 Ophiuchi/GX 1+4, The Neutron Star Symbiotic
We have computed, based on 17 infrared radial velocities, the first set of
orbital elements for the M giant in the symbiotic binary V2116 Ophiuchi. The
giant's companion is a neutron star, the bright X-ray source GX 1+4. We find an
orbital period of 1161 days by far the longest of any known X-ray binary. The
orbit has a modest eccentricity of 0.10 with an orbital circularization time of
less than 10^6 years. The large mass function of the orbit significantly
restricts the mass of the M giant. Adopting a neutron-star mass of 1.35M(Sun),
the maximum mass of the M giant is 1.22M(Sun), making it the less massive star.
Derived abundances indicate a slightly subsolar metallicity. Carbon and
nitrogen are in the expected ratio resulting from the red-giant first dredge-up
phase. The lack of O-17 suggests that the M-giant has a mass less than
1.3M(Sun), consistent with our maximum mass. The red giant radius is 103R(Sun),
much smaller than the estimated Roche lobe radius. Thus, the mass loss of the
red giant is via a stellar wind. Although the M giant companion to the neutron
star has a mass similar to the late-type star in low-mass X-ray binaries, its
near-solar abundances and apparent runaway velocity are not fully consistent
with the properties of this class of stars.Comment: In press to The Astrophysical Journal (10 April 2006 issue). 23 page
Impact of intentionally injected carbon dioxide hydrate on deep-sea benthic foraminiferal survival
Author Posting. © The Authors, 2009. This is the author's version of the work. It is posted here by permission of Blackwell for personal use, not for redistribution. The definitive version was published in Global Change Biology 15 (2009): 2078-2088, doi:10.1111/j.1365-2486.2008.01822.x.Sequestration of carbon dioxide (CO2) in the ocean is being considered as a feasible mechanism to mitigate the alarming rate in its atmospheric rise. Little is known, however, about how the resulting hypercapnia and ocean acidification may affect marine fauna. In an effort to understand better the protistan reaction to such an environmental perturbation, the survivorship of benthic foraminifera, which is a prevalent group of protists, was studied in response to deep-sea CO2 release. The survival response of calcareous, agglutinated, and thecate foraminifera was determined in two experiments at ~3.1 and 3.3 km water depth in Monterey Bay (California, USA). Approximately five weeks after initial seafloor CO2 release, in situ incubations of the live-dead indicator CellTracker Green were executed within seafloor-emplaced pushcores. Experimental treatments included direct exposure to CO2 hydrate, two levels of lesser exposure adjacent to CO2 hydrate, and controls, which were far removed from the CO2 hydrate release. Results indicate that survivorship rates of agglutinated and thecate foraminifera were not significantly impacted by direct exposure but the survivorship of calcareous foraminifera was significantly lower in direct exposure treatments compared to controls. Observations suggest that, if large scale CO2 sequestration is enacted on the deep-sea floor, survival of two major groups of this prevalent protistan taxon will likely not be severely impacted, while calcareous foraminifera will face considerable challenges to maintain their benthic populations in areas directly exposed to CO2 hydrate.This work was funded by the Monterey Bay Aquarium Research Institute (project 200002; to JPB), US Department of Energy grant # DE-FG02-03ER63696 (to J. P. Kennett and J.M.B.), and NSF OCE-0725966 (to J.M.B.)
Tracking vocabulary and reading growth in children from lower and higher socioeconomic backgrounds during the transition from primary to secondary education
We examined the relation between socioeconomic status (SES), vocabulary, and reading in middle childhood, during the transition from primary (elementary) to secondary (high) school. Children (N = 279, 163 girls) completed assessments of everyday and curriculum‐related vocabulary, (non)word reading, and reading comprehension at five timepoints from age 10 to 13. Piecewise linear mixed‐effects models showed significant growth in everyday vocabulary and word reading between every time point. Curriculum vocabulary and reading comprehension showed significant growth during the school year, but not during the summer holidays. There were significant effects of SES on all measures except word reading; yet, SES differences did not widen over time. Our findings motivate targeted reading and vocabulary support for secondary school students from lower SES backgrounds
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