169 research outputs found
Non-steller light from high-redshift radiogalaxies
With the aid of a new IRCAM image of 3C356, researchers question the common assumption that radiosource-stimulated starbursts are responsible for the extended optical emission aligned with radio structures in high-redshift radiogalaxies. They propose an alternative model in which the radiation from a hidden luminous quasar is beamed along the radio axis and illuminates dense clumps of cool gas to produce both extended narrow emission line regions and, by Thomson scattering, extended optical continua. Simple observational tests of this model are possible and necessary if we are to continue to accept that the color, magnitude and shape evolution of radiogalaxies are controlled by the active evolution of stellar populations
The Linear-Size Evolution of Classical Double Radio Sources
Recent investigations of how the median size of extragalactic radio sources
change with redshift have produced inconsistent results. Eales compared the
radio and optical properties of a bright 3C and faint 6C sample and concluded
that (), with being the median
size of the radio sources at a given epoch and z the redshift. Oort, Katgert,
and Windhorst, on the other hand, from a comparison of the properties of a
number of radio samples, found much stronger evolution, with
. In this paper we attempt to resolve the
difference. We have repeated the analysis of Eales using the virtually complete
redshift information that now exists for the 6C sample. Confining our analysis
to FR2 sources, which we argue is the best-understood class of radio sources
and the least likely to be affected by selection effects, we find
() and
(). Our complete redshift information allows us to gain insight
into our result by plotting a radio luminosity-size (P-D) diagram for the 6C
sample. The most obvious difference between the 3C and 6C P-D diagrams is the
clump of sources in the 6C diagram at . These clump sources have similar sizes to the emission-line
regions found around high-redshift radio galaxies, suggesting that the presence
of dense line-emitting gas around high-redshift radio galaxies is responsible
for the size evolution. We show that this explanation can quantitatively
explain the observed size evolution, as long as there is either little X-ray
emitting gas around these objects or, if there is, it is distributed in a
similar way to the emission-line gas: highly anisotropic and inhomogeneous.Comment: compressed and uuencoded postscript file. 33 pages including 5
figures (441951 bytes). Accepted for publication in September Ap
The radio luminosity function from the low-frequency 3CRR, 6CE & 7CRS complete samples
We measure the radio luminosity function (RLF) of steep-spectrum radio
sources using three redshift surveys of flux-limited samples selected at low
(151 & 178 MHz) radio frequency, low-frequency source counts and the local RLF.
The redshift surveys used are the new 7C Redshift Survey (7CRS) and the
brighter 3CRR and 6CE surveys totalling 356 sources with virtually complete
redshift information. This yields unprecedented coverage of the radio
luminosity versus z plane for steep-spectrum sources, and hence the most
accurate measurements of the steep-spectrum RLF yet made. We find that a simple
dual-population model for the RLF fits the data well, requiring differential
density evolution (with z) for the two populations. The low-luminosity
population can be associated with radio galaxies with weak emission lines, and
includes sources with both FRI and FRII radio structures; its comoving space
density rises by about one dex between z~0 and z~1 but cannot yet be
meaningfully constrained at higher redshifts. The high-luminosity population
can be associated with FRII radio galaxies and quasars with strong emission
lines; its rises by nearly three dex between z~0 and z~2. These results
mirror the situation seen in X-ray and optically-selected AGN. The integrated
radio luminosity density of the combination of the two populations is
controlled by the value of at the low-luminosity end of the RLF of the
high-luminosity population, a quantity which has been directly measured at z~1
by the 7CRS. We argue that robust determination of this quantity at higher
redshifts requires a new redshift survey based on a large (~1000 source) sample
about five times fainter than the 7CRS.Comment: 20 pages, 16 figures, accepted for publication in MNRA
A sample of 6C radio sources designed to find objects at redshift > 4: the radio data
We describe the selection of a sample of 34 radio sources from the 6C survey
(Hales, Baldwin & Warner 1993) from a region of sky covering 0.133 sr. The
selection criteria for this sample, hereafter called 6C*, were chosen to
optimise the chances of finding radio galaxies at redshift z > 4. Optical
follow-up observations have already led to the discovery of the most distant
known radio galaxy at z = 4.41 (Rawlings et al. 1996). We present VLA radio
maps and derive radio spectra for all the 6C* objects.Comment: 18 pages, LaTeX; also available at
http://www-astro.physics.ox.ac.uk/research/preprints/ To appear in MNRA
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Using Interleukin 6 and 8 in Blood and Bronchoalveolar Lavage Fluid to Predict Survival in Hematological Malignancy Patients With Suspected Pulmonary Mold Infection.
Background: Molds and other pathogens induce elevated levels of several cytokines, including interleukin (IL)-6 and IL-8. The objective of this study was to investigate the prognostic value of IL-6 and IL-8 as well as fungal biomarkers in blood and bronchoalveolar lavage fluid (BAL) for overall survival in patients with underlying hematological malignancies and suspected mold infection. Methods: This cohort study included 106 prospectively enrolled adult cases undergoing bronchoscopy. Blood samples were collected within 24 h of BAL sampling and, in a subset of 62 patients, serial blood samples were collected up until 4 days after bronchoscopy. IL-6, IL-8, and other cytokines as well as galactomannan (GM) and β-D-glucan (BDG) were assayed in blood and BAL fluid and associations with overall mortality were assessed at the end of the study using receiver operating characteristic (ROC) curve analysis. Results: Both blood IL-8 (AUC 0.731) and blood IL-6 (AUC 0.699) as well as BAL IL-6 (AUC 0.763) and BAL IL-8 (AUC 0.700) levels at the time of bronchoscopy were predictors of 30-day all-cause mortality. Increasing blood IL-6 levels between bronchoscopy and day four after bronchoscopy were significantly associated with higher 90-day mortality, with similar findings for increasing IL-8 levels. In ROC analysis the difference of blood IL-8 levels between 4 days after bronchoscopy and the day of bronchoscopy had an AUC of 0.829 (95%CI 0.71-0.95; p < 0.001) for predicting 90-day mortality. Conclusions: Elevated levels of IL-6 and IL-8 in blood or BAL fluid at the time of bronchoscopy, and rising levels in blood 4 days following bronchoscopy were predictive of mortality in these patients with underlying hematological malignancy who underwent bronchoscopy for suspected mold infection
Perturbation of the P-Body Component Mov10 Inhibits HIV-1 Infectivity
Exogenous retroviruses are obligate cellular parasites that co-opt a number of host proteins and functions to enable their replication and spread. Several host factors that restrict HIV and other retroviral infections have also recently been described. Here we demonstrate that Mov10, a protein associated with P-bodies that has a putative RNA-helicase domain, when overexpressed in cells can inhibit the production of infectious retroviruses. Interestingly, reducing the endogenous Mov10 levels in virus-producing cells through siRNA treatment also modestly suppresses HIV infectivity. The actions of Mov10 are not limited to HIV, however, as ectopic expression of Mov10 restricts the production of other lentiviruses as well as the gammaretrovirus, murine leukemia virus. We found that HIV produced in the presence of high levels of Mov10 is restricted at the pre-reverse transcription stage in target cells. Finally, we show that either helicase mutation or truncation of the C-terminal half of Mov10, where a putative RNA-helicase domain is located, maintained most of its HIV inhibition; whereas removing the N-terminal half of Mov10 completely abolished its activity on HIV. Together these results suggest that Mov10 could be required during the lentiviral lifecycle and that its perturbation disrupts generation of infectious viral particles. Because Mov10 is implicated as part of the P-body complex, these findings point to the potential role of cytoplasmic RNA processing machinery in infectious retroviral production
Protein tyrosine phosphatase PTPN22 regulates LFA-1 dependent Th1 responses
A missense C1858T single nucleotide polymorphism within PTPN22 is a strong genetic risk factor for the development of multiple autoimmune diseases. PTPN22 encodes a protein tyrosine phosphatase that negatively regulates immuno-receptor proximal Src and Syk family kinases. Notably, PTPN22 negatively regulates kinases downstream of T-cell receptor (TCR) and LFA-1, thereby setting thresholds for T-cell activation. Alterations to the quality of TCR and LFA-1 engagement at the immune synapse and the regulation of downstream signals can have profound effects on the type of effector T-cell response induced. Here we describe how IFNγ+ Th1 responses are potentiated in Ptpn22−/− T-cells and in T-cells from mice expressing Ptpn22R619W (the mouse orthologue of the human genetic variant) as they age, or following repeated immune challenge, and explore the mechanisms contributing to the expansion of Th1 cells. Specifically, we uncover two LFA-1-ICAM dependent mechanisms; one T-cell intrinsic, and one T-cell extrinsic. Firstly, we found that in vitro anti-CD3/LFA-1 induced Th1 responses were enhanced in Ptpn22−/− T-cells compared to WT, whereas anti-CD3/anti-CD28 induced IFNy responses were similar. These data were associated with an enhanced ability of Ptpn22−/− T-cells to engage ICAM-1 at the immune synapse when incubated on planar lipid bilayers, and to form conjugates with dendritic cells. Secondly, we observed a T-cell extrinsic mechanism whereby repeated stimulation of WT OT-II T-cells with LPS and OVA323-339 pulsed Ptpn22−/− bone marrow derived dendritic cells (BMDCs) was sufficient to enhance Th1 cell development compared to WT BMDCs. Furthermore, this response could be reversed by LFA-1 blockade. Our data point to two related but distinct mechanisms by which PTPN22 regulates LFA-1 dependent signals to enhance Th1 development, highlighting how perturbations to PTPN22 function over time to regulate the balance of the immune response
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“My Death Will Not [Be] in Vain”: Testimonials from Last Gift Rapid Research Autopsy Study Participants Living with HIV at the End of Life
End-of-life (EOL) HIV cure-related research provides a novel approach to studying HIV reservoirs. The Last Gift is a rapid autopsy research study at the University of California San Diego that enrolls terminally ill people living with HIV (PLWHIV) with a desire to contribute to HIV cure-related research. We conducted in-depth baseline and follow-up interviews with Last Gift study participants. We analyzed interview data applying conventional content analysis. Since summer 2017, 13 participants have been enrolled (n = 11 males and 2 females; aged 45-89 years) and 8 participants interviewed. Terminal illnesses included cancers, heart diseases, and neurodegenerative illnesses. Our analysis revealed five key themes: (1) The Last Gift study has tremendous meaning for participants at the end of their life. (2) HIV-specific altruism was a primary motivator to join the Last Gift study, nested within the context of community, scientific advancement, and moral obligation. (3) Participants did not expect physical benefits yet they perceived emotional/psychological, financial, and societal/scientific benefits. (4) There were minimal participant-perceived risks and concerns. (5) Last Gift participants expressed immense gratitude toward study staff. The Last Gift study provides a framework for ethical HIV cure-related research at EOL and highlighted participants' perspectives, motivations, and experiences. Knowing how PLWHIV understand and experience such studies will remain critical to designing ethical, fully informed HIV cure research protocols that are acceptable to PLWHIV
Classifying organisms and artefacts by their outline shapes
We often wish to classify objects by their shapes. Indeed, the study of shapes is an important part of many scientific fields, such as evolutionary biology, structural biology, image processing and archaeology. However, mathematical shape spaces are rather complicated and nonlinear. The most widely used methods of shape analysis, geometric morphometrics, treat the shapes as sets of points. Diffeomorphic methods consider the underlying curve rather than points, but have rarely been applied to real-world problems. Using a machine classifier, we tested the ability of several of these methods to describe and classify the shapes of a variety of organic and man-made objects. We find that one method, based on square-root velocity functions (SRVFs), outperforms all others, including a standard geometric morphometric method (eigenshapes), and that it is also superior to human experts using shape alone. When the SRVF approach is constrained to take account of homologous landmarks it can accurately classify objects of very different shapes. The SRVF method identifies a shortest path between shapes, and we show that this can be used to estimate the shapes of intermediate steps in evolutionary series. Diffeomorphic shape analysis methods, we conclude, now provide practical and effective solutions to many shape description and classification problems in the natural and human sciences.</p
Randomized controlled trial comparing three different modalities of lithotrites for intracorporeal lithotripsy in pcnl
Purpose: To compare the efficiency (stone fragmentation and removal time) and complications of three models of intracorporeal lithotripters in percutaneous nephrolithotomy (PCNL). Materials and Methods: Prospective, randomized controlled trial at nine centers in the North America from 2009 to 2016. Patients were randomized to one of three lithotripter devices: the Cyberwand, a dual probe ultrasonic device; the Swiss Lithoclast Select, a combination pneumatic and ultrasonic device; and the StoneBreaker, a portable pneumatic device powered by CO2 cartridges. Since the StoneBreaker lacks an ultrasonic component, it was used with the LUS‐II ultrasonic lithotripter to allow fair comparison with combination devices. Results: 270 patients were enrolled, 69 were excluded after randomization. 201 patients completed the study: 71 in the Cyberwand group, 66 in the Lithoclast Select, and 64 in the StoneBreaker group. The baseline patient characteristics of the three groups were similar. Mean stone surface area was smaller in the StoneBreaker group at 407.8mm2 vs 577.5mm2 (Lithoclast Select) and 627.9mm2 (Cyberwand). The stone clearance rate was slowest in the StoneBreaker group at 24.0 mm2/min vs 28.9 mm2/min and 32.3 mm2/min in the Lithoclast Select and Cyberwand groups respectively. After statistically adjusting for the smaller mean stone size in the StoneBreaker group, there was no difference in the stone clearance rate among the three groups (p=0.249). Secondary outcomes, including complications and stone free rates, were similar between the groups. Conclusions: The Cyberwand, Lithoclast Select, and the StoneBreaker lithotripters have similar adjusted stone clearance rates in PCNL for stones > 2cm. The safety and efficacy of these devices are comparable
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