1,525 research outputs found

    The structure of the solutions to semilinear equations at a critical exponent

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    This paper is concerned with the structure of the solutions to subcritical elliptic equations related to the Matukuma equation. In certain cases the complete structure of the solution set is known, and is comparable to that of the original Matukuma equation. Here we derive sufficient conditions for a more complicated solution set consisting of; (i) crossing solutions for small initial conditions and large initial conditions; (ii) at least one open interval of slowly decaying solutions; and (iii) at least two rapidly decaying solutions. As a consequence we obtain multiplicity results for rapidly decaying, or minimal solutions

    Round Cells of the Epidermis: Clues from Studies on Neoplastic Lymphocytes of Cutaneous T Cell Lymphoma

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    Neoplastic cells of cutaneous T cell lymphoma (CTCL) appear to be of monoclonal origin and frequently are nonspecific helpers of normal B cell differentiation. A natural progression from epidermotropic (mycosis fungoides and Sézary syndrome) to nonepidermotropic, more widely disseminated T cell neoplasms generally occurs. Affinity of CTCL cells for the epidermis may result from their having membrane receptors for histocompatibility (Ia) antigens present in skin. Cultured human epidermal cells produce a thymopoietin-like molecule, an indication of a role for skin in T cell differentiation

    Potential for cogeneration of heat and electricity in California industry, phase 2

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    The nontechnical issues of industrial cogeneration for 12 California firms were analyzed under three categories of institutional settings: (1) industrial ownership without firm sales of power; (2) industrial ownership with firm sales of power; and (3) utility or third party ownership. Institutional issues were analyzed from the independent viewpoints of the primary parties of interest: the industrial firms, the electric utilities and the California Public utilities Commission. Air quality regulations and the agencies responsible for their promulgation were examined, and a life cycle costing model was used to evaluate the economic merits of representative conceptual cogeneration systems at these sites. Specific recommendations were made for mitigating measures and regulatory action relevant to industrial cogeneration in California

    A simultaneous XMM-Newton and BeppoSAX observation of the archetypal Broad Line Seyfert 1 galaxy NGC 5548

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    We report the spectral analysis of a long XMM-Newton observation of the well-studied, moderate luminosity Broad Line Seyfert 1 galaxy NGC 5548. The source was at an historically average brightness and we find the hard (3-10 keV) spectrum can be well fitted by a power law of photon index gamma ~ 1.75, together with reflection. The only feature in the hard X-ray spectrum is a narrow emission line near 6.4 keV, with an equivalent width of ~ 60 eV. The energy and strength of this line is consistent with fluorescence from `neutral' iron distant from the central continuum source. We find no evidence for a broad Fe K line, with an upper limit well below previous reports, suggesting the inner accretion disc is now absent or highly ionised. The addition of simultaneous BeppoSAX data allows the analysis to be extended to 200 keV, yielding important constraints on the total reflection. Extrapolation of the hard X-ray power law down to 0.3 keV shows a clear `soft excess' below ~ 0.7 keV. After due allowance for the effects of a complex warm absorber, measured with the XMM-Newton RGS, we find the soft excess is better described as a smooth upward curvature in the continuum flux below ~ 2 keV. The soft excess can be modelled either by Comptonised thermal emission or by enhanced reflection from the surface of a highly ionised disc.Comment: 9 pages, 11 figures, accepted by MNRAS; minor changes to text and figure

    High Temporal Resolution XMM Monitoring of PKS 2155-304

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    The bright, strongly variable BL Lac object PKS 2155-304 was observed by XMM for two essentially uninterrupted periods of ~11 and 16 hr on 30-31 May 2000. The strongest variations occurred in the highest energy bands. After scaling for this effect, the three softest bands (0.1-1.7 keV) showed strong correlation with no measurable lag to reliable limits of \tau \ls 0.3 hr. However, the hardest band (~3 keV) was less well-correlated with the other three, especially on short time scales, showing deviations of ~10-20% in ~1 hr although, again, no significant interband lag was detected. This result and examination of previous ASCA and BeppoSAX cross-correlation functions suggest that previous claims of soft lags on time scales of 0.3-4 hr could well be an artifact of periodic interruptions due to Earth-occultation every 1.6 hr. Previous determinations of the magnetic field/bulk Lorentz factor were therefore premature, as these data provide only a lower limit of B \gamma^{1/3} \gs 2.5 G. The hardest band encompasses the spectral region above the high-energy break; its enhanced variability could be indicating that the break energy of the synchrotron spectrum, and therefore of the underlying electron energy distribution, changes independently of the lower energies.Comment: 13 pages, 3 figures, accepted by Ap

    Complex X-ray spectral variability in Mkn 421 observed with XMM-Newton

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    The bright blazar Mkn 421 has been observed four times for uninterrupted durations of ~ 9 - 13 hr during the performance verification and calibration phases of the XMM-Newton mission. The source was strongly variable in all epochs, with variability amplitudes that generally increased to higher energy bands. Although the detailed relationship between soft (0.1 - 0.75 keV) and hard (2 - 10 keV) band differed from one epoch to the next, in no case was there any evidence for a measurable interband lag, with robust upper limits of τ<0.08| \tau | < 0.08 hr in the best-correlated light curves. This is in conflict with previous claims of both hard and soft lags of ~1 hr in this and other blazars. However, previous observations suffered a repeated 1.6 hr feature induced by the low-Earth orbital period, a feature that is not present in the uninterrupted XMM-Newton data. The new upper limit on τ|\tau| leads to a lower limit on the magnetic field strength and Doppler factor of B \delta^{1/3} \gs 4.7 G, mildly out of line with the predictions from a variety of homogeneous synchrotron self-Compton emission models in the literature of Bδ1/3=0.20.8 B \delta^{1/3} = 0.2 - 0.8 G. Time-dependent spectral fitting was performed on all epochs, and no detectable spectral hysteresis was seen. We note however that the source exhibited significantly different spectral evolutionary behavior from one epoch to the next, with the strongest correlations in the first and last and an actual divergance between soft and hard X-ray bands in the third. This indicates that the range of spectral variability behavior in Mkn 421 is not fully described in these short snippets; significantly longer uninterrupted light curves are required, and can be obtained with XMM-Newton.Comment: 21 pages, 4 figures, accepted for ApJ, scheduled for August 1, 200

    Rapid construction of a dendritic cell vaccine through physical perturbation and apoptotic malignant T cell loading

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    We have demonstrated that adherence and release of monocytes from a plastic surface drives their differentiation into immature dendritic cells (DC,) that can mature further during overnight incubation in the presence of apoptotic malignant T cells. Based on these results, we sought to develop a clinically, practical, rapid means for producing DC loaded with malignant cells. A leukapheresis harvest containing the clonal, leukemic expansion of malignant CD4(+ )T cells was obtained from the blood of patients with cutaneous T cell lymphoma (CTCL). CTCL cells were purified with a CD3-magnetic bead column where CD3 engagement rendered the malignant T cells apoptotic. The monocyte fraction was simultaneously activated by column passage, re-added to the apoptotic CTCL cells and co-cultured overnight. CTCL cell apoptosis, DC differentiation and apoptotic malignant T cell ingestion were measured by immunostaining. The results demonstrate that as monocytes passed through the column matrix, they became activated and differentiated into semi-mature DC expressing significantly increased levels of class II, CD83 and CD86 (markers associated with maturing DC) and reduced expression of the monocyte markers CD14 and CD36. Apoptotic malignant T cells were avidly engulfed by the phagocytic transitioning DC. The addition of supportive cytokines further enhanced the number of DC that contained apoptotic malignant T cells. Functional studies confirmed that column passaged DC increased class II expression as shown by significantly enhanced stimulation in mixed leukocyte culture compared to control monocytes. In addition, DC loaded with apoptotic CTCL cells stimulated an increase in the percentage and absolute number of CD8 T cells compared to co-cultivation with non-loaded DC. After CD8 T cells were stimulated by DC loaded with malignant cells, they mediated increased apoptosis of residual CTCL cells and TNF-α secretion indicating development of enhanced cytolytic function. We report a simple one-step procedure where maturing DC containing apoptotic malignant T cells can be prepared rapidly for potential use in vaccine immunotherapy. Ready access to both the DC and apoptotic cells provided by this system will allow extension to other malignancies through the addition of a variety of apoptotic tumor cells and maturation stimuli
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