A new solid-phase system for immunoassays

The development of a new solid-phase separation system based on silane polymers is described. A T3 radioimmunoassay (RIA) was optimized using coated tubes with polymer coatings containing hydrophilic surface aldehyde groups for antibody coupling and a T4 RIA developed on the basis of surface anilino group containing particles using a suspension method. Both RIAs offer very good performances and show the variable usability of the new separation system

potential biomarkers of haemophilic arthropathy correlations with compatible additive magnetic resonance imaging scores

Introduction: Although biomarkers are useful diagnostic tools to assess joint damage in osteoarthritis and rheumatoid arthritis, few data exist for biomarkers of haemophilic arthropathy. Aim: To evaluate the association between biomarkers and compatible additive magnetic resonance imaging (MRI) scores in patients with severe haemophilia A. Methods: Patients aged 12–35 years with no history of factor VIII (FVIII) inhibitors were enrolled in a controlled, cross-sectional, multinational investigation. Patients received primary or secondary prophylaxis or on-demand treatment with FVIII and underwent MRI on four joints (two ankles, two knees). Soluble biomarkers of cartilage and bone degradation, inflammation, and angiogenesis were assessed (serum levels of C-terminal telopeptides of type I collagen [CTX-I], cartilage oligomeric matrix protein [COMP], chondroitin-sulphate aggrecan turnover 846 epitope [CS846], tissue inhibitor of metalloproteinase 1 [TIMP-1]; plasma levels of vascular endothelial growth factor [VEGF], matrix metalloproteinases 3 and 9 [MMP3, MMP9]). Relationships between biomarkers and MRI scores were evaluated using Spearman rank correlation. Results: Biomarkers were assessed in 117 of 118 per-protocol patients. Mean and median CTX-I, COMP, TIMP-1, MMP3, MMP9, and VEGF values were within normal ranges (reference range not available for CS846 in healthy volunteers). No correlations between biomarkers and MRI scores were found, with the exception of CS846, which showed significant correlation in a subgroup of 22 on-demand patients (r = 0.436; P = 0.04). Conclusions: Compatible additive MRI scores showed no clear correlations with any of the potential biomarkers for haemophilic arthropathy in the overall population. CS846 levels were significantly correlated with MRI scores in patients treated on demand. (Less

A synchrotron self-Compton model with low energy electron cut-off for the blazar S5 0716+714

Rapid inverse Compton cooling sets in when the brightness temperature (T_B) of a self-absorbed synchrotron source with power-law electrons reaches ~10^{12} K. However, T_B inferred from observations of intra-day variable sources (IDV) are well above the "Compton catastrophe" limit. This can be understood if the underlying electron distribution cuts off at low energy. We approximate a low-energy cut-off with monoenergetic electrons. We compute the synchrotron self-Compton (SSC) spectrum of such distribution, and using the IDV source S5~0716+714 as an example, we compare it to the observed SED of S5~0716+714. The hard radio spectrum is well-fitted by this model, and the optical data can be accommodated by a power-law extension to the electron spectrum. We therefore examine the scenario of an injection of electrons that is a double power law in energy with a hard low-energy component that does not contribute to the synchrotron opacity. We show that the double power-law injection model is in good agreement with the observed SED of S5~0716+714. For intrinsic variability, we find that a Doppler factor of D\geq30 can explain the observed SED provided that low-frequency (<32 GHz) emission originates from a larger region than the higher-frequency emission. To fit the entire spectrum, D\geq65 is needed. We find the constraint imposed by induced Compton scattering at high T_B is insignificant in our model. We confirm that electron distribution with a low-energy cut-off can explain the high T_B in compact radio sources. We show that synchrotron spectrum from such distributions naturally accounts for the observed hard radio continuum with a softer optical component, without the need for an inhomogeneous source.Comment: 13 pages, 5 figures, 1 table, to appear in A&A; refereces removed from caption of Fig.3, added acknowledgemen

Superluminal Motion and Relativistic Beaming in Blazar Jets

High resolution radio observations remain the most direct way to study the formation and evolution of radio jets associated with the accretion onto massive black holes. We report preliminary results of our seven year VLBA observational program to understand the nature of relativistic beaming in blazars and the surrounding environment of massive black holes. Most blazars show an apparent outward flow away from an active core. However, in a few sources the motion appears inward, most likely the result of projection of a curved trajectory which bends back toward along the line of sight. The apparent motion of jet features is not always oriented along the direction separating the feature from the core, and in a few cases we have observed a clear change in the direction and velocity of a feature as it flows along the jet. In other sources, the motion appears to follow a simple ballistic trajectory. We find no simple relation between the time scales of flux density changes and apparent component velocities.Comment: To Appear in "High Energy Blazar Astronomy", Eds: L. O. Takalo and E. Valtaoja, 8 pages, 3 figure

The angular size - redshift relation in power-law cosmologies

A linear evolution of the cosmological scale factor is a feature in several models designed to solve the cosmological constant problem via a coupling between scalar or tensor classical fields to the space-time curvature as well as in some alternative gravity theories. In this paper, by assuming a general time dependence of the scale factor, $R \sim t^{\alpha}$, we investigate observational constraints on the dimensionless parameter $\alpha$ from measurements of the angular size for a large sample of milliarcsecond compact radio sources. In particular, we find that a strictly linear evolution, i.e., $\alpha \simeq 1$ is favoured by these data, which is also in agreement with limits obtained from other independent cosmological tests. The dependence of the critical redshift $z_m$ (at which a given angular size takes its minimal value) with the index $\alpha$ is briefly discussed.Comment: 5 pages, 4 figures, LaTe

High brightness temperatures and circular polarisation in extra-galactic radio sources

Some rapidly variable extra-galactic radio sources show very high brightness temperatures T_B>10^{12}K and high degrees of circular polarisation (1%). Standard synchrotron models that assume a power-law electron distribution cannot produce such high temperatures and have much lower degrees of intrinsic circular polarisation. We examine the synchrotron and inverse Compton radiation from a monoenergetic electron distribution using standard synchrotron theory. Constraints on the source parameters are found by formulating the results as functions of the source size, Doppler boosting factor, optical depth to synchrotron self-absorption, maximum frequency of synchrotron emission, and the strength of the inverse Compton radiation. The model gives brightness temperatures T_B=10^{13}K to 10^{14}K for moderate (<10) Doppler boosting factors and intrinsic degrees of circular polarisation at the percent level. It predicts a spectrum I_\nu\propto\nu^{1/3} between the radio and the infra-red as well as emission in the MeV to GeV range. We find the conditions under which electrons do not cool within the source, enabling the GHz emission to emerge without absorption and the potentially catastrophic energy losses by inverse Compton scattering to be avoided. We suggest that sources such as PKS 1519 -273, PKS 0405 -385 and J 1819 +3845 can be understood within this scenario without invoking high Doppler boosting factors, coherent emission mechanisms, or the dominance of proton synchrotron radiation.Comment: 4 pages, to appear in A&A Letter

Spectral Energy Distributions of type 2 QSOs: obscured star formation at high redshifts

We present new mid-infrared and submillimetre observations for a sample of eight high redshift type-2 QSOs located in the Chandra Deep Field South. The sources are X-ray absorbed with luminosities in excess of 10^44 erg/s. Two of the targets have robust detections, S/N > 4, while a further three targets are marginally detected with S/N > =2.5. All sources are detected in multiple mid-infrared bands with the Spitzer Space Telescope. The multiwavelength spectral energy distributions (SEDs) of the type-2 QSOs are compared to those of two local ultraluminous galaxies (Arp220 and IR22491) in order to assess contributions from a star-forming component in various parts of the SED. We suggest that their submillimetre emission is possibly due to a starburst while a large fraction of the mid-infrared energy is likely to originate in the obscured central quasar. Using the mid-infrared and submm observations we derive infrared luminosities which are found to be in excess of L>10^12Lsun. The submillimetre (850micron) to X-ray (2 keV) spectral indices (alpha_SX) span a wide range. About half of the type-2 QSOs have values typical for a Compton-thick AGN with only 1 per cent of the nuclear emission seen through scattering and, the remaining with values typical of submm-bright galaxies. Combining the available observational evidence we outline a possible scenario for the early stages of evolution of these sources.Comment: Accepted for publication in MNRA

Engaging with issues of emotionality in mathematics teacher education for social justice

This article focuses on the relationship between social justice, emotionality and mathematics teaching in the context of the education of prospective teachers of mathematics. A relational approach to social justice calls for giving attention to enacting socially-just relationships in mathematics classrooms. Emotionality and social justice in teaching mathematics variously intersect, interrelate or interweave. An intervention, usng creative action methods, with a cohort of prospective teachers addressing these issues is described to illustrate the connection between emotionality and social justice in the context of mathematics teacher education. Creative action methods involve a variety of dramatic, interactive and experiential tools that can promote personal and group engagement and embodied reflection. The intervention aimed to engage the prospective teachers with some key issues for social justice in mathematics education through dialogue about the emotionality of teaching and learning mathematics. Some of the possibilities and limits of using such methods are considered

The ISOPHOT-MAMBO survey of 3CR radio sources: Further evidence for the unified schemes

We present the complete set of ISOPHOT observations of 3CR radio galaxies and quasars, which are contained in the ISO Data Archive, providing 75 mid- and far-infrared spectral energy distributions (SEDs) between 5 and 200 micron. For 28 sources they are supplemented with MAMBO 1.2 mm observations and for 15 sources with new submillimetre data from the SCUBA archive. We check the orientation-dependent unified scheme, in which the powerful FR2 narrow line galaxies are quasars viewed at high inclination, so that their nuclei are hidden behind a dust torus intercepting the optical-ultraviolet AGN radiation and reemitting it in the infrared. We find that (1) both the quasars and the galaxies show a high mid- to far-infrared luminosity ratio typical for powerful AGNs and (2) -- when matched in 178 MHz luminosity -- both show the same ratio of isotropic far-infrared to isotropic 178 MHz lobe power. Therefore, from our large sample investigated here we find strong evidence for the orientation-dependent unification of the powerful FR2 galaxies with the quasars.Comment: 16 pages, 7 figures, 3 tables, accepted by Astronomy & Astrophysic