4,685 research outputs found
A Case of Reactive Cervical Lymphadenopathy with Fat Necrosis Impinging on Adjacent Vascular Structures.
A tender neck mass in adults can be a diagnostic challenge due to a wide differential diagnosis, which ranges from reactive lymphadenopathy to malignancy. In this report, we describe a case of a young female with an unusually large and tender reactive lymph node with fat necrosis. The diagnostic imaging findings alone mimicked that of scrofula and malignancy, which prompted a complete workup. Additionally, the enlarged lymph node was compressing the internal jugular vein in the setting of oral contraceptive use by the patient, raising concern for Lemierre's syndrome or internal jugular vein thrombosis. This report shows how, in the appropriate clinical context, and especially with the involvement of adjacent respiratory or neurovascular structures, aggressive diagnostic testing can be indicated
Malignant melanoma in Chile: different site distribution between private and state patients
BACKGROUND: The body site location of primary Malignant Melanoma (MM) has been correlated with prognosis and survival. Ethnic, genetics, sun exposure factors are related to the anatomical distribution of MM. Low and high socioeconomic strata in Chile differ in ethnic, genetic and cultural conditions. The purpose of this study was to analyze the anatomical MM distribution in the Chilean population in both strata searching for differences due to their ethno-genetic-cultural differences. Records of 1148 MM, 575cases from state hospitals (Low Socioeconomic Strata, LSS) and 573 cases from private clinics (High Socioeconomic Strata, HSS) were analyzed by body site. RESULTS: Females from LSS showed a higher number of MM in soles, cheeks, and around the eye area. Females from the HSS showed a higher number of MM in dorsal feet and dorsal hands. Males from LSS showed a higher number of MM in soles, around the eye area, and cheeks. However, males from HSS showed a higher number of MM in the trunk, and in the arms. Acral MM was significantly higher in LSS than in the HSS in both sexes. The Chilean population from the HSS and LSS showed differences in the distribution of MM by site. Furthermore, gender differences in the proportion of MM analyzed by anatomical site are observed in both strata. CONCLUSIONS: Results show evidence that differential genetics factors, sun exposure, or other environmental or cultural factors of both strata may account for these differences
Differences between urban and rural hedges in England revealed by a citizen science project
Background: Hedges are both ecologically and culturally important and are a distinctive feature of the British landscape. However the overall length of hedges across Great Britain is decreasing. Current challenges in studying hedges relate to the dominance of research on rural, as opposed to urban, hedges, and their variability and geographical breadth. To help address these challenges and to educate the public on the importance of hedge habitats for wildlife, in 2010 the Open Air Laboratories (OPAL) programme coordinated a hedge-focused citizen science survey. Results: Results from 2891 surveys were analysed. Woody plant species differed significantly between urban and rural areas. Beech, Holly, Ivy, Laurel, Privet and Yew were more commonly recorded in urban hedges whereas Blackthorn, Bramble, Dog Rose, Elder and Hawthorn were recorded more often in rural hedges. Urban and rural differences were shown for some groups of invertebrates. Ants, earwigs and shieldbugs were recorded more frequently in urban hedges whereas blowflies, caterpillars, harvestmen, other beetles, spiders and weevils were recorded more frequently in rural hedges. Spiders were the most frequently recorded invertebrate across all surveys. The presence of hard surfaces adjacent to the hedge was influential on hedge structure, number and diversity of plant species, amount of food available for wildlife and invertebrate number and diversity. In urban hedges with one adjacent hard surface, the food available for wildlife was significantly reduced and in rural hedges, one adjacent hard surface affected the diversity of invertebrates. Conclusions: This research highlights that urban hedges may be important habitats for wildlife and that hard surfaces may have an impact on both the number and diversity of plant species and the number and diversity of invertebrates. This study demonstrates that citizen science programmes that focus on hedge surveillance can work and have the added benefit of educating the public on the importance of hedgerow habitats
Ultra-stable performance of an underground-based laser interferometer observatory for gravitational waves
In order to detect the rare astrophysical events that generate gravitational
wave (GW) radiation, sufficient stability is required for GW antennas to allow
long-term observation. In practice, seismic excitation is one of the most
common disturbances effecting stable operation of suspended-mirror laser
interferometers. A straightforward means to allow more stable operation is
therefore to locate the antenna, the ``observatory'', at a ``quiet'' site. A
laser interferometer gravitational wave antenna with a baseline length of 20m
(LISM) was developed at a site 1000m underground, near Kamioka, Japan. This
project was a unique demonstration of a prototype laser interferometer for
gravitational wave observation located underground. The extremely stable
environment is the prime motivation for going underground. In this paper, the
demonstrated ultra-stable operation of the interferometer and a well-maintained
antenna sensitivity are reported.Comment: 8 pages, to appear on PR
Distorted cyclotron line profile in Cep X-4 as observed by NuSTAR
We present spectral analysis of NuSTAR and Swift observations of Cep X-4
during its outburst in 2014. We observed the source once during the peak of the
outburst and once during the decay, finding good agreement in the spectral
shape between the observations. We describe the continuum using a powerlaw with
a Fermi-Dirac cutoff at high energies. Cep X-4 has a very strong cyclotron
resonant scattering feature (CRSF) around 30 keV. A simple absorption-like line
with a Gaussian optical depth or a pseudo-Lorentzian profile both fail to
describe the shape of the CRSF accurately, leaving significant deviations at
the red side of the line. We characterize this asymmetry with a second
absorption feature around 19 keV. The line energy of the CRSF, which is not
influenced by the addition of this feature, shows a small but significant
positive luminosity dependence. With luminosities between (1-6)e36 erg/s, Cep
X-4 is below the theoretical limit where such a correlation is expected. This
behavior is similar to Vela X-1 and we discuss parallels between the two
systems.Comment: 6 pages, 4 figure, accepted for publication in ApJ letter
An extended communication inequalities approach to disparities in obesity preventive behaviors
This dissertation integrates the theory of planned behavior (TPB) with information exposure and concepts from the communication inequality perspective with the purpose of identifying disparities between the more and less advantaged segments of society throughout the communication for behavioral change process. It was expected to find differences in exposure to health information, as well as differences in the degree to which attitudes, norms, and perceived behavioral control (PBC) influence intentions, and the degree to which intentions lead to behavior. To test the hypotheses and research questions, structural equation modelling and multigroup analysis using MPlus 7.2 were conducted. Two datasets were analyzed, the first one from the Youth Media Campaign Longitudinal Survey (YMCLS), which was conducted with the purpose of assessing the effect of the VERB media campaign in a nationally representative sample of children aged 9 to 13 years and their parents between 2004 and 2006 (N = 2,773). The second study corresponds to a two-Wave survey among female adolescents conducted in schools in Santiago, Chile (N = 751). In the first study, the effect of exposure to the VERB campaign on the practice of physical activity two years later was examined through a mediation model. In the second study, the effect of seeking and scanning information about physical activity and fruit and vegetable consumption in the practice of the respective behaviors was examined, also with a mediation model. In the context of physical activity, across the two studies the main tenets of the TPB held, as norms and PBC were positive and significantly associated with intentions, which in turn led to the practice of the behavior. Furthermore, mediated effects of norms and PBC via intentions were supported in the two studies. The integration of the TPB with information exposure also received support in the two studies, with exposure to the VERB campaign being a significant predictor of attitudes and PBC, and indirectly influencing physical activity via PBC and intentions. In the Chile study, information scanning led to positive attitudes, norms, and PBC, and indirectly affected behavior though attitudes, PBC, and intentions. Information seeking, however, was negatively associated with behavior, both directly and mediated by other variables in the model. With respect to the disparities in the communication for behavioral change process it was found that children and adolescents from more disadvantaged backgrounds reported lower levels of exposure to the campaign and to health information. Moreover, subjects from more advantaged backgrounds were able to turn their intentions into behavioral change, whereas subjects from less advantaged backgrounds were not. Some results regarding the moderating role of social position indicators were unexpected for example, the positive association between exposure to the VERB campaign and attitudes only among children from less advantaged backgrounds. Taken together, the results of the two studies presented in this dissertation support an integration of the TPB with the concepts of information exposure and the moderation of social position indicators, as suggested by the communication inequality approach to better understand disparities in the communication for behavioral change process
Brauer-Thrall for totally reflexive modules over local rings of higher dimension
Let be a commutative Noetherian local ring. Assume that has a pair
of exact zerodivisors such that and all totally
reflexive -modules are free. We show that the first and second
Brauer--Thrall type theorems hold for the category of totally reflexive
-modules. More precisely, we prove that, for infinitely many integers ,
there exists an indecomposable totally reflexive -module of multiplicity
. Moreover, if the residue field of is infinite, we prove that there
exist infinitely many isomorphism classes of indecomposable totally reflexive
-modules of multiplicity .Comment: to appear in Algebras and Representation Theor
Cyclotron harmonics in opacities of isolated neutron star atmospheres
Some of X-ray dim isolated neutron stars (XDINS) and central compact objects
in supernova remnants (CCO) show absorption features in their thermal soft
X-ray spectra. It has been hypothesized that these features could be due to the
periodic peaks in free-free absorption opacities, caused by either Landau
quantization of electron motion in magnetic fields B<10^{11} G or analogous
quantization of ion motion in magnetic fields B>10^{13} G. Here, I review the
physics behind cyclotron quantum harmonics in free-free photoabsorption,
discuss different approximations for their calculation, and explain why the ion
cyclotron harmonics (beyond the fundamental) cannot be observed.Comment: 12 pages, 5 figures. In v.5, a typo (missed sign factor) in Eq.(9) is
fixe
Statistical equilibrium and ion cyclotron absorption/emission in strongly magnetized plasmas
We calculate the transition rates between proton Landau levels due to
non-radiative and radiative Coulomb collisions in an electron-proton plasma
with strong magnetic field B. Both electron-proton collisions and proton-proton
collisions are considered. The roles of the first-order cyclotron absorption
and second-order free-free absorption and scattering in determining the line
strength and shape as well as the continuum are analysed in detail. We solve
the statistical balance equation for the populations of proton Landau levels.
For temperatures \sim 10^6-10^7 K, the deviations of the proton populations
from LTE are appreciable at density \rho < 0.1 B_{14}^{3.5} g cm^{-3}, where
B_{14}=B/(10^{14} G). We present general formulae for the plasma emissivity and
absorption coefficents under a wide range of physical conditions. Our results
are useful for studying the possibility and the conditions of proton/ion
cyclotron line formation in the near vicinity of highly magnetized neutron
stars.Comment: 17 pages, 8 figures, MNRAS, accepte
Exploring morphological correlations among H2CO, 12CO, MSX and continuum mappings
There are relatively few H2CO mappings of large-area giant molecular cloud
(GMCs). H2CO absorption lines are good tracers for low-temperature molecular
clouds towards star formation regions. Thus, the aim of the study was to
identify H2CO distributions in ambient molecular clouds. We investigated
morphologic relations among 6-cm continuum brightness temperature (CBT) data
and H2CO (111-110; Nanshan 25-m radio telescope), 12CO (1--0; 1.2-m CfA
telescope) and midcourse space experiment (MSX) data, and considered the impact
of background components on foreground clouds. We report simultaneous 6-cm H2CO
absorption lines and H110\alpha radio recombination line observations and give
several large-area mappings at 4.8 GHz toward W49 (50'\times50'), W3
(70'\times90'), DR21/W75 (60'\times90') and NGC2024/NGC2023 (50'\times100')
GMCs. By superimposing H2CO and 12CO contours onto the MSX color map, we can
compare correlations. The resolution for H2CO, 12CO and MSX data was about 10',
8' and 18.3", respectively. Comparison of H2CO and 12CO contours, 8.28-\mu m
MSX colorscale and CBT data revealed great morphological correlation in the
large area, although there are some discrepancies between 12CO and H2CO peaks
in small areas. The NGC2024/NGC2023 GMC is a large area of HII regions with a
high CBT, but a H2CO cloud to the north is possible against the cosmic
microwave background. A statistical diagram shows that 85.21% of H2CO
absorption lines are distributed in the intensity range from -1.0 to 0 Jy and
the \Delta V range from 1.206 to 5 km/s.Comment: 18 pages, 22 figures, 5 tables. Accepted to be published in
Astrophysics and Space Scienc
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