Heavily reddened type 1 quasars at z > 2 I: Evidence for significant obscured black-hole growth at the highest quasar luminosities

We present a new population of z>2 dust-reddened, Type 1 quasars with 0.5<E(B-V)<1.5, selected using near infra-red (NIR) imaging data from the UKIDSS-LAS, ESO-VHS and WISE surveys. NIR spectra obtained using the Very Large Telescope (VLT) for 24 new objects bring our total sample of spectroscopically confirmed hyperluminous (>10^{13}L_0), high-redshift dusty quasars to 38. There is no evidence for reddened quasars having significantly different H$\alpha$ equivalent widths relative to unobscured quasars. The average black-hole masses (~10^9-10^10 M_0) and bolometric luminosities (~10^{47} erg/s) are comparable to the most luminous unobscured quasars at the same redshift, but with a tail extending to very high luminosities of ~10^{48} erg/s. Sixty-six per cent of the reddened quasars are detected at $>3\sigma$ at 22um by WISE. The average 6um rest-frame luminosity is log10(L6um/erg/s)=47.1+/-0.4, making the objects among the mid-infrared brightest AGN currently known. The extinction-corrected space-density estimate now extends over three magnitudes (-30 < M_i < -27) and demonstrates that the reddened quasar luminosity function is significantly flatter than that of the unobscured quasar population at z=2-3. At the brightest magnitudes, M_i < -29, the space density of our dust-reddened population exceeds that of unobscured quasars. A model where the probability that a quasar becomes dust-reddened increases at high luminosity is consistent with the observations and such a dependence could be explained by an increase in luminosity and extinction during AGN-fuelling phases. The properties of our obscured Type 1 quasars are distinct from the heavily obscured, Compton-thick AGN that have been identified at much fainter luminosities and we conclude that they likely correspond to a brief evolutionary phase in massive galaxy formation.Comment: 16 pages, 9 figures (+ 2 appendices), Accepted for publication in MNRA

Correcting CIV-Based Virial Black Hole Masses

The CIV broad emission line is visible in optical spectra to redshifts exceeding z~5. CIV has long been known to exhibit significant displacements to the blue and these `blueshifts' almost certainly signal the presence of strong outflows. As a consequence, single-epoch virial black hole (BH) mass estimates derived from CIV velocity-widths are known to be systematically biased compared to masses from the hydrogen Balmer lines. Using a large sample of 230 high-luminosity (log $L_{\rm Bol}$ = 45.5-48 erg/s), redshift 1.5<z<4.0 quasars with both CIV and Balmer line spectra, we have quantified the bias in CIV BH masses as a function of the CIV blueshift. CIV BH masses are shown to be a factor of five larger than the corresponding Balmer-line masses at CIV blueshifts of 3000 km/s and are over-estimated by almost an order of magnitude at the most extreme blueshifts, >5000 km/s. Using the monotonically increasing relationship between the CIV blueshift and the mass ratio BH(CIV)/BH(H$\alpha$) we derive an empirical correction to all CIV BH-masses. The scatter between the corrected CIV masses and the Balmer masses is 0.24 dex at low CIV blueshifts (~0 km/s) and just 0.10 dex at high blueshifts (~3000 km/s), compared to 0.40 dex before the correction. The correction depends only on the CIV line properties - i.e. full-width at half maximum and blueshift - and can therefore be applied to all quasars where CIV emission line properties have been measured, enabling the derivation of un-biased virial BH mass estimates for the majority of high-luminosity, high-redshift, spectroscopically confirmed quasars in the literature.Comment: Accepted for publication in MNRAS; fixed typo in CIV wavelengt

Preservation and accessibility of audio-visual records in Tanzania’s television broadcasting companies

This study investigated the preservation and accessibility of audio-visual records in television broadcasting companies in Tanzania. Specifically, it set out to determine how audio-visual records are preserved in television broadcasting companies; to establish how audio-visual records in television broadcasting companies in Tanzania are accessed and to examine challenges to effective preservation and accessing of audiovisual records in television broadcasting companies in Tanzania. The literature reviewed and the findings from pilot study indicate that many AV records are produced by individuals, television companies and other entities in both rural and urban Tanzania. They also indicate that there are intervening factors such as resource constraints, technological incompatibility, inadequate infrastructure, inadequate skills, environmental factors, and unclear policies the hinder access to and use of audio-visual records. Since the preservation and accessibility to audio-visual records is challenging due to intervening factors, it is recommended that approaches used (passive preservation and active preservation) to preserve audio-visual records be constantly reviewed to identify strategies that could be used to address challenges as they arise in order to improve preservation and accessibility of the relevant records.Keywords: Audio-visual records, Records Preservation, Records Accessibility, Tanzani

EAER: An alternative and effective remineralization method

This article describes with the newer technologies that are used in the remineralization procedure of tooth thus avoiding usage of drills on the tooth structure and preserving the enamel as a whole. A number of finer and newer technologies are being developed so that procedures can be more friendly and acceptable to both the dentist as well as the patient, these newer strategies are also concerned in preserving the tooth structure as a whole without the introduction off any foreign material, thus increasing the life as well as the strength of the tooth structure. This paper deals with the various newer strategies in brief and in detailed about the electrically driven technique named EAER

Study on safety of non-descent vaginal hysterectomy for enlarged uterine size for benign uterine pathologies

Background: Vaginal hysterectomy is less commonly performed for benign pathologies if the uterine size exceeds 12 weeks in the belief that complications could be higher in this group. The aim of this prospective study was to compare surgical outcomes and safety of vaginal hysterectomy in women with non-prolapsed uteri of >12 weeks size to those with uteri of12 weeks), while the control group consisted of 60 women with uteri 0.05). The mean operative time was significantly longer in the index group (62.47min; vs 48.17 min; p 0.05). Intra- and post-operative complications such as blood transfusion and pelvic sepsis, post-operative febrile illness and systemic infections were comparable in both groups.Conclusions: Vaginal hysterectomy in larger non-prolapsed uteri takes longer to perform and is associated with more blood loss compared to uteri <12 weeks but is not associated with a significant increase in complication rates

Mathematical modeling of R5 and X4 HIV : from within host dynamics to the epidemiology of HIV infection.

M. Sc. University of KwaZulu-Natal, Pietermaritzburg 2015.Most existing models have considered the immunological processes occurring within the host and the epidemiological processes occurring at population level as decoupled systems. We present a new model using continuous systems of non linear ordinary differential equations by directly linking the within host dynamics capturing the interactions between Langerhans cells, CD4+ T-Cells, R5 HIV and X4 HIV and the without host dynamics of a basic compartmental HIV/AIDS, susceptible, infected, AIDS model. The model captures the biological theories of the cells that take part in HIV transmission. The study incorporates in its analysis the differences in time scales of the fast within host dynamics and the slow without host dynamics. In the mathematical analysis, important thresholds, the reproduction numbers, were computed which are useful in predicting the progression of the infection both within the host and without the host. The study results showed that the model exhibits four within host equilibrium points inclusive of three endemic equilibria whose effects translate into different scenarios at the population level. All the endemic equilibria were shown to be globally stable using Lyapunov functions and this is an important result in linking the within host dynamics to the population dynamics, because the disease free equilibrium point ceases to exist. The linked models had no effect on the basic reproduction numbers of the within host dynamics but on the basic reproduction number of the population dynamics. The effects of linking were observed on the endemic equilibrium points of both the within host and population dynamics. Therefore, linking the two dynamics leads to the increase in the viral load within the host and increase in the epidemic levels in the population dynamics