125 research outputs found
Self-Similar Scalar Field Collapse: Naked Singularities and Critical Behaviour
Homothetic scalar field collapse is considered in this article. By making a
suitable choice of variables the equations are reduced to an autonomous system.
Then using a combination of numerical and analytic techniques it is shown that
there are two classes of solutions. The first consists of solutions with a
non-singular origin in which the scalar field collapses and disperses again.
There is a singularity at one point of these solutions, however it is not
visible to observers at finite radius. The second class of solutions includes
both black holes and naked singularities with a critical evolution (which is
neither) interpolating between these two extremes. The properties of these
solutions are discussed in detail. The paper also contains some speculation
about the significance of self-similarity in recent numerical studies.Comment: 27 pages including 5 encapsulated postcript figures in separate
compressed file, report NCL94-TP1
Tumor infiltrating effector memory Antigen-Specific CD8+ T Cells predict response to immune checkpoint therapy
Immune checkpoint therapy (ICT) results in durable responses in individuals with some cancers, but not all patients respond to treatment. ICT improves CD8+ cytotoxic T lymphocyte (CTL) function, but changes in tumor antigen-specific CTLs post-ICT that correlate with successful responses have not been well characterized. Here, we studied murine tumor models with dichotomous responses to ICT. We tracked tumor antigen-specific CTL frequencies and phenotype before and after ICT in responding and non-responding animals. Tumor antigen-specific CTLs increased within tumor and draining lymph nodes after ICT, and exhibited an effector memory-like phenotype, expressing IL-7R (CD127), KLRG1, T-bet, and granzyme B. Responding tumors exhibited higher infiltration of effector memory tumor antigen-specific CTLs, but lower frequencies of regulatory T cells compared to non-responders. Tumor antigen-specific CTLs persisted in responding animals and formed memory responses against tumor antigens. Our results suggest that increased effector memory tumor antigen-specific CTLs, in the presence of reduced immunosuppression within tumors is part of a successful ICT response. Temporal and nuanced analysis of T cell subsets provides a potential new source of immune based biomarkers for response to ICT
Thermodynamic properties of excess-oxygen-doped La2CuO4.11 near a simultaneous transition to superconductivity and long-range magnetic order
We have measured the specific heat and magnetization {\it versus} temperature
in a single crystal sample of superconducting LaCuO and in a
sample of the same material after removing the excess oxygen, in magnetic
fields up to 15 T. Using the deoxygenated sample to subtract the phonon
contribution, we find a broad peak in the specific heat, centered at 50 K. This
excess specific heat is attributed to fluctuations of the Cu spins possibly
enhanced by an interplay with the charge degrees of freedom, and appears to be
independent of magnetic field, up to 15 T. Near the superconducting transition
(=0)= 43 K, we find a sharp feature that is strongly suppressed when
the magnetic field is applied parallel to the crystallographic c-axis. A model
for 3D vortex fluctuations is used to scale magnetization measured at several
magnetic fields. When the magnetic field is applied perpendicular to the
c-axis, the only observed effect is a slight shift in the superconducting
transition temperature.Comment: 8 pages, 8 figure
Nariai, Bertotti-Robinson and anti-Nariai solutions in higher dimensions
We find all the higher dimensional solutions of the Einstein-Maxwell theory
that are the topological product of two manifolds of constant curvature. These
solutions include the higher dimensional Nariai, Bertotti-Robinson and
anti-Nariai solutions, and the anti-de Sitter Bertotti-Robinson solutions with
toroidal and hyperbolic topology (Plebanski-Hacyan solutions). We give explicit
results for any dimension D>3. These solutions are generated from the
appropriate extremal limits of the higher dimensional near-extreme black holes
in a de Sitter, and anti-de Sitter backgrounds. Thus, we also find the mass and
the charge parameters of the higher dimensional extreme black holes as a
function of the radius of the degenerate horizon.Comment: 10 pages, 11 figures, RevTeX4. References added. Published versio
Spin stiffness and quantum fluctuations in C-type and A-type antiferromagnets
We present a systematic study of quantum fluctuations in the C-type and
A-type antiferromagnetic (AF) phases in cubic lattices and in bilayer systems.
Using the linear spin-wave theory, we show that the spin stiffness and the
quantum corrections to the order parameter and energy obtained for C-AF and
A-AF phases decrease with the increasing number of ferromagnetic bonds.
Therefore, the quantum spin effects in LaMnO_3 and in LaVO_3 are rather small,
suggesting the magnetic moments of 3.91 and 1.89 Bohr's magneton, respectively.
They cannot explain the strong reduction of the magnetic order parameter
observed in cubic vanadates.Comment: 6 pages, 4 figure
Collapsing shear-free perfect fluid spheres with heat flow
A global view is given upon the study of collapsing shear-free perfect fluid
spheres with heat flow. We apply a compact formalism, which simplifies the
isotropy condition and the condition for conformal flatness. This formalism
also presents the simplest possible version of the main junction condition,
demonstrated explicitly for conformally flat and geodesic solutions. It gives
the right functions to disentangle this condition into well known differential
equations like those of Abel, Riccati, Bernoulli and the linear one. It yields
an alternative derivation of the general solution with functionally dependent
metric components. We bring together the results for static and time- dependent
models to describe six generating functions of the general solution to the
isotropy equation. Their common features and relations between them are
elucidated. A general formula for separable solutions is given, incorporating
collapse to a black hole or to a naked singularity.Comment: 26 page
Feasibility assessment of patient reporting of symptomatic adverse events in multicenter cancer clinical trials
IMPORTANCE: In cancer clinical trials, symptomatic adverse events (AEs), such as nausea, are reported by investigators rather than by patients. There is increasing interest to collect symptomatic AE data via patient-reported outcome (PRO) questionnaires, but it is unclear whether it is feasible to implement this approach in multicenter trials. OBJECTIVE: To examine whether patients are willing and able to report their symptomatic AEs in multicenter trials. DESIGN, SETTING, AND PARTICIPANTS: A total of 361 consecutive patients enrolled in any 1 of 9 US multicenter cancer treatment trials were invited to self-report 13 common symptomatic AEs using a PRO adaptation of the National Cancer Instituteâs Common Terminology Criteria for Adverse Events (CTCAE) via tablet computers at 5 successive clinic visits. Patient adherence was tracked with reasons for missed self-reports. Agreement with clinician AE reports was analyzed with weighted Îș statistics. Patient and investigator perspectives were elicited by survey. The study was conducted from March 15, 2007, to August 11, 2011. Data analysis was performed from August 9, 2013, to March 21, 2014. RESULTS: Of the 361 patients invited to participate, 285 individuals enrolled, with a median age of 57 years (range, 24-88), 202 (74.3%) female, 241 (85.5%) white, 73 (26.8%) with a high school education or less, and 176 (64.7%) who reported regular internet use (denominators varied owing to missing data). Across all patients and trials, there were 1280 visits during which patients had an opportunity to self-report (ie, patients were alive and enrolled in a treatment trial at the time of the visit). Self-reports were completed at 1202 visits (93.9% overall adherence). Adherence was highest at baseline and declined over time (visit 1, 100%; visit 2, 96%; visit 3, 95%; visit 4, 91%; and visit 5, 85%). Reasons for missing PROs included institutional errors in 27 of 48 (56.3%) of the cases (eg, staff forgetting to bring computers to patients at visits), patients feeling âtoo illâ in 8 (16.7%), patient refusal in 8 (16.7%), and internet connectivity problems in 5 (10.4%). Patient-investigator CTCAE agreement was moderate or worse for most symptoms (most Îș < 0.05), with investigators reporting fewer AEs than patients across symptoms. Most patients believed that the system was easy to use (234 [93.2%]) and useful (230 [93.1%]), and investigators thought that the patient-reported AEs were useful (133 [94.3%]) and accurate (119 [83.2%]). CONCLUSIONS AND RELEVANCE: Participants in multicenter cancer trials are willing and able to report their own symptomatic AEs at most clinic visits and report more AEs than investigators. This approach may improve the precision of AE reporting in cancer trials
The VANDELS ESO public spectroscopic survey
VANDELS is a uniquely deep spectroscopic survey of high-redshift galaxies with the VIMOS spectrograph on ESOâs Very Large Telescope (VLT). The survey has obtained ultradeep optical (0.48 < λ < 1.0 ÎŒ m) spectroscopy of â2100 galaxies within the redshift interval 1.0 †z †7.0, over a total area of â0.2 deg2 centred on the CANDELS Ultra Deep Survey and Chandra Deep Field South fields. Based on accurate photometric redshift pre-selection, 85âperâcent of the galaxies targeted by VANDELS were selected to be at z â„ 3. Exploiting the red sensitivity of the refurbished VIMOS spectrograph, the fundamental aim of the survey is to provide the high-signal-to-noise ratio spectra necessary to measure key physical properties such as stellar population ages, masses, metallicities, and outflow velocities from detailed absorption-line studies. Using integration times calculated to produce an approximately constant signal-to-noise ratio (20 < tint< 80 h), the VANDELS survey targeted: (a) bright star-forming galaxies at 2.4 †z †5.5, (b) massive quiescent galaxies at 1.0 †z †2.5, (c) fainter star-forming galaxies at 3.0 †z †7.0, and (d) X-ray/Spitzer-selected active galactic nuclei and Herschel-detected galaxies. By targeting two extragalactic survey fields with superb multiwavelength imaging data, VANDELS will produce a unique legacy data set for exploring the physics underpinning high-redshift galaxy evolution. In this paper, we provide an overview of the VANDELS survey designed to support the science exploitation of the first ESO public data release, focusing on the scientific motivation, survey design, and target selection
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