498 research outputs found
Bacillary angiomatosis in HIV-infected patients - An epidemiological and clinical study
Background: No data were available on the epidemiological and clinical characteristics of bacillary angiomatosis (BA) in Germany. Objective:To determine epidemiological and clinical data on HIV-associated BA. Methods: A chart review of all BA cases between 1990 and 1998 was performed in 23 German AIDS treatment units. Results: A total of 21 cases of BA was diagnosed. During th is period, the participating HIV centers treated about 17,000 HIV-infected patients. As a result, a BA prevalence of 1.2 cases/1,000 patients can be assumed. 19 BA were localized in the skin; in 5 cases bones and in 4 cases the liver were involved. Out of 20 patients who received antibiotic therapy, 13 had complete remission. The median time of duration up to complete remission was 32 days (9-82), During the follow-up of the 20 patients, 7 relapses were observed, Conclusion: BA is a rare HIV-associated disease with a prevalence of 1,2 cases/1,000 patients in the presented study. Copyright (C) 2000 S. Karger AG, Basel
Teaching âin their best interestâ: Preservice teachers\u27 narratives regarding English Learners
In the United States, teachers are increasingly working with English Learners (ELs) in mainstream classrooms. Several areas of focus have been proposed to guide the preparation of teachers for working with ELs, including: language related knowledge, skills, and dispositions. This narrative study examined how field-based experiences shaped 49 preservice teachers\u27 dispositions toward ELs. An iterative and thematic analysis of collected narratives found that preservice teachers often completed their practicum in classrooms that did not model positive dispositions or pedagogical practices toward ELs. These findings have implications for the tasks and experiences given to preservice teachers during their preparation sequence
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When is Foreign Exchange Intervention Effective? Evidence from 33 Countries
This paper examines foreign exchange intervention based on novel daily data covering 33 countries from 1995 to 2011. We find that intervention is widely used and an effective policy tool, with a success rate in excess of 80 percent under some criteria. The policy works well in terms of smoothing the path of exchange rates, and in stabilizing the exchange rate in countries with narrow band regimes. Moving the level of the exchange rate in flexible regimes requires that some conditions are met, including the use of large volumes and that intervention is made public and supported via communication
The effect of minihaloes on cosmic reionization
One of the most debated issues in the theoretical modeling of cosmic
reionization is the impact of small-mass gravitationally-bound structures. We
carry out the first numerical investigation of the role of such sterile
`minihaloes', which serve as self-shielding screens of ionizing photons.
Minihaloes are too small to be properly resolved in current large-scale
cosmological simulations, and thus we estimate their effects using a sub-grid
model, considering two cases that bracket their effect within this framework.
In the `extreme suppression' case in which minihalo formation ceases once a
region is partially ionized, their effect on cosmic reionization is modest,
reducing the volume-averaged ionization fraction by an overall factor of less
than 15%. In the other extreme, in which minihalo formation is never
suppressed, they delay complete reionization as much as Delta z~2, in rough
agreement with the results from a previous semi-analytical study by the
authors. Thus, depending on the details of the minihalo formation process,
their effect on the overall progress of reionization can range from modest to
significant, but the minihalo photon consumption is by itself insufficient to
force an extended reionization epoch.Comment: 9 pages, 2 figures, accepted for pubblication in MNRA
Long-distance remote comparison of ultrastable optical frequencies with 1e-15 instability in fractions of a second
We demonstrate a fully optical, long-distance remote comparison of
independent ultrastable optical frequencies reaching a short term stability
that is superior to any reported remote comparison of optical frequencies. We
use two ultrastable lasers, which are separated by a geographical distance of
more than 50 km, and compare them via a 73 km long phase-stabilized fiber in a
commercial telecommunication network. The remote characterization spans more
than one optical octave and reaches a fractional frequency instability between
the independent ultrastable laser systems of 3e-15 in 0.1 s. The achieved
performance at 100 ms represents an improvement by one order of magnitude to
any previously reported remote comparison of optical frequencies and enables
future remote dissemination of the stability of 100 mHz linewidth lasers within
seconds.Comment: 7 pages, 4 figure
Fibroblast growth factor receptor (FGFR) alterations in squamous differentiated bladder cancer: a putative therapeutic target for a small subgroup.
Although drugable fibroblast growth factor receptor (FGFR) alterations in squamous cell carcinomas (SCC) of various entities are well known, little is known about FGFR modifications in squamous differentiated bladder cancer. Therefore, our study evaluated FGFR1-3 alterations as a putative therapeutic target in this subgroup. We analyzed 73 squamous differentiated bladder cancers (n = 10 pT2, n = 55 pT3, n = 8 pT4) for FGFR1-3 protein expression, FGFR1-3 copy number variations, FGFR3 chromosomal rearrangements (fluorescence in situ hybridization (FISH)) and FGFR3 mutations (SNapShot analysis). Only single cases displayed enhanced protein expression, most frequently FGFR3 overexpression (9.4% (6/64)). FISH showed no amplifications of FGFR1, 2 or 3. Break apart events were only slightly above the cut off in 12.1% (8/66) of cases and no FGFR3-TACC3 rearrangements could be proven by qPCR. FGFR3 mutations (p.S249C) were found in 8.5% (6/71) of tumors and were significantly associated with FGFR3 protein overexpression (p < 0.001), and unfavourable clinical outcome (p = 0.001). Our findings are consistent with the results of the TCGA data set for the "squamous-like" subtype of bladder cancer (n = 85), which revealed reduced overall expression of FGFR1 and FGFR2 in tumors compared to normal tissue, while expression of FGFR3 remained high. In the TCGA "squamous-like" subtype FGFR3 mutations were found in 4.9% and correlated with high FGFR3 RNA expression. Mutations of FGFR1 and FGFR2 were less frequent (2.4% and 1.2%). Hence, our comprehensive study provides novel insights into a subgroup of squamous differentiated bladder tumors that hold clues for novel therapeutic regimens and may benefit from FGFR3-targeted therapies
The Observed and Predicted Spatial Distribution of Milky Way Satellite Galaxies
We review evidence that the census of Milky Way satellites similar to those
known may be incomplete at low latitude due to obscuration and in the outer
halo due to a decreasing sensitivity to dwarf satellites with distance. We
evaluate the possible impact that incompleteness has on comparisons with
substructure models by estimating corrections to the known number of dwarfs
using empirical and theoretical models. If we assume that the true distribution
of Milky Way satellites is uniform with latitude, then we estimate a 33%
incompleteness in the total number of dwarfs due to obscuration at low
latitude. Similarly, if we suppose that the radial distribution of Milky Way
satellites matches that of M31, or that of the oldest sub-halos or the most
massive sub-halos in a simulation, we estimate a total number of Milky Way
dwarfs ranging from 1 -- 3 times the known population. Although the true level
of incompleteness is quite uncertain, the fact that our extrapolations yield
average total numbers of MW dwarfs that are realistically 1.5 -- 2 times the
known population, shows that incompleteness needs to be taken seriously when
comparing to models of dwarf galaxy formation. Interestingly, the radial
distribution of the oldest sub-halos in a Lambda+CDM simulation of a Milky
Way-like galaxy possess a close match to the observed distribution of M31's
satellites, which suggests that reionization may be an important factor
controlling the observability of sub-halos. We also assess the prospects for a
new SDSS search for Milky Way satellites to constrain the possible
incompleteness in the outer halo.Comment: 9 pages, 7 figures. Replaced with MNRAS accepted versio
The VO: A Powerful Tool for Global Astronomy
Since its inception in the early 2000's, the Virtual Observatory (VO), developed as a collaboration of many national and international projects, has become a major factor in the discovery and dissemination of astronomical information worldwide. The International Virtual Observatory Alliance (IVOA) has been coordinating all these efforts worldwide to ensure a common VO framework that enables transparent access to and interoperability of astronomy resources (data and software) around the world. The VO is not a magic solution to all astronomy data management challenges but it does bring useful solutions in many areas borne out by the fact that VO interfaces are broadly found in astronomy's major data centres and projects worldwide. Astronomy data centres have been building VO services on top of their existing data services to increase interoperability with other VO-compliant data resources to take advantage of the continuous and increasing development of VO applications. VO applications have made multi-instrument and multi-wavelength science, a difficult and fruitful part of astronomy, somewhat easier. More recently, several major new astronomy projects have been directly adopting VO standards to build their data management infrastructure, giving birth to âVO built-in' archives. Embracing the VO framework from the beginning brings the double gain of not needing to reinvent the wheel and ensuring from the start interoperability with other astronomy VO resources. Some of the IVOA standards are also starting to be used by neighbour disciplines like planetary sciences. There is still quite a lot to be done on the VO, in particular tackling the upcoming big data challenge and how to find interoperable solutions to the new data analysis paradigm of bringing and running the software close to the data. We report on the current status and also desire to encourage others to adopt VO technology and engage them in the effort of developing the VO. Thus, we wish to ensure that the VO standards fit new astronomy projects requirements and needs
Functional improvement and maturation of rat and human engineered heart tissue by chronic electrical stimulation
Spontaneously beating engineered heart tissue (EHT) represents an advanced in vitro model for drug testing and disease modeling, but cardiomyocytes in EHTs are less mature and generate lower forces than in the adult heart. We devised a novel pacing system integrated in a setup for videooptical recording of EHT contractile function over time and investigated whether sustained electrical field stimulation improved EHT properties. EHTs were generated from neonatal rat heart cells (rEHT, n=96) or human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hEHT, n=19). Pacing with biphasic pulses was initiated on day 4 of culture. REHT continuously paced for 16-18 days at 0.5Hz developed 2.2Ă higher forces than nonstimulated rEHT. This was reflected by higher cardiomyocyte density in the center of EHTs, increased connexin-43 abundance as investigated by two-photon microscopy and remarkably improved sarcomere ultrastructure including regular M-bands. Further signs of tissue maturation include a rightward shift (to more physiological values) of the Ca(2+)-response curve, increased force response to isoprenaline and decreased spontaneous beating activity. Human EHTs stimulated at 2Hz in the first week and 1.5Hz thereafter developed 1.5Ă higher forces than nonstimulated hEHT on day 14, an ameliorated muscular network of longitudinally oriented cardiomyocytes and a higher cytoplasm-to-nucleus ratio. Taken together, continuous pacing improved structural and functional properties of rEHTs and hEHTs to an unprecedented level. Electrical stimulation appears to be an important step toward the generation of fully mature EHT
Towards quantitative control on discreteness error in the non-linear regime of cosmological N body simulations
The effects of discreteness arising from the use of the N-body method on the
accuracy of simulations of cosmological structure formation are not currently
well understood. After a discussion of how the relevant discretisation
parameters introduced should be extrapolated to recover the Vlasov-Poisson
limit, we study numerically, and with analytical methods we have developed
recently, the central issue of how finite particle density affects the
precision of results. In particular we focus on the power spectrum at
wavenumbers around and above the Nyquist wavenumber, in simulations in which
the force resolution is taken smaller than the initial interparticle spacing.
Using simulations of identical theoretical initial conditions sampled on four
different "pre-initial" configurations (three different Bravais lattices, and a
glass) we obtain a {\it lower bound} on the real discreteness error. With the
guidance of our analytical results, we establish with confidence that the
measured dispersion is not contaminated either by finite box size effects or by
subtle numerical effects. Our results show notably that, at wavenumbers {\it
below} the Nyquist wavenumber, the dispersion increases monotonically in time
throughout the simulation, while the same is true above the Nyquist wavenumber
once non-linearity sets in. For normalizations typical of cosmological
simulations, we find lower bounds on errors at the Nyquist wavenumber of order
of a percent, and larger above this scale. The only way this error may be
reduced below these levels at these scales, and indeed convergence to the
physical limit firmly established, is by extrapolation, at fixed values of the
other relevant parameters, to the regime in which the mean comoving
interparticle distance becomes less than the force smoothing scale.Comment: 26 pages, 15 figures, minor changes, slightly shortened, version to
be published in MNRA
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