The Effect of Dust Extinction on the Observed Properties of Galaxies in the Near-Infrared

Galaxies behind the Milky Way suffer size reduction and dimming due to their obscuration by dust in the disk of our Galaxy. The degree of obscuration is wavelength dependent. It decreases towards longer wavelengths. Compared to the optical, the Near InfraRed (NIR) $K_s$ band extinction is only $\approx10$ that of the $B$ band. This makes NIR surveys well suited for galaxy surveys close to the Galactic Plane where extinction is severe. While Galactic obscuration is less prominent in the NIR it is not negligible. In this paper we derive empirical relations to correct isophotal radii and magnitudes of galaxies observed in the NIR for foreground absorption. We simulate extinction in the $J$, $H$ and $K_s$ bands on 64 (unobscured) galaxies from the 2MASS Large Galaxy Atlas \citep{jarrett}. We propose two methods for the extinction correction, the first is optimized to provide the most accurate correction and the second provides a convenient statistical correction that works adequately in lower extinction regions. The optimized correction utilizes the galaxy surface brightness, either the disk central surface brightness, $\mu_0$, or the combined disk plus bulge central surface brightness, elliptical and disk/spiral Hubble types. A detailed comparison between the different methods and their accuracy is provided.Comment: 9 pages, 8 figures and 8 tables. Accepted by the MNRAS: Accepted 2009 September 18. Received 2009 September 18; in original form 2009 July 1

Flat Cosmology with Coupled Matter and Dark Energies

Three models of a flat universe of coupled matter and dark energies with different low-redshift parameterizations of the dark energy equation of state are considered. The dark energy is assumed to vary with time like the trace of the energy-momentum tensor of cosmic matter. In the radiation-dominated era the models reduce to standard cosmology. In the matter-dominated era they are, for modern values of the cosmological parameters, consistent with data from SNe Ia searches and with the data of Gurvits et al.(1999)for angular sizes of ultra compact radio sources. We find that the angular size-redshift tests for our models offer a higher statistical confidence than that based on SNe Ia data. A comparison of our results with a recent revised analysis of angular size-redshift legacy data is made,and the implications of our models with optimized relativistic beaming in the radio sources is discussed. In particular we find that relativistic beaming implies a Lorentz factor less than 6,in agreement with its values for powerful Active Galactic Nuclei.Comment: Version to appear in The Astronomical Journal, with a modified name- Flat Cosmology with Coupled Matter and Dark Energies. Expanded and Modified conten

Signals for Non-Commutative QED in eγe \gamma and γγ\gamma \gamma Collisions

We study the effects of non-commutative QED (NCQED) in fermion pair production, gamma + gamma -> f + bar{f} and Compton scattering, e + gamma -> e + gamma. Non-commutative geometries appear naturally in the context of string/M-theory and gives rise to 3- and 4-point photon vertices and to momentum dependent phase factors in QED vertices which will have observable effects in high energy collisions. We consider e+ e- colliders with energies appropriate to the TeV Linear Collider proposals and the multi-TeV CLIC project operating in gamma gamma and e gamma modes. Non-commutative scales roughly equal to the center of mass energy of the e+ e- collider can be probed, with the exact value depending on the model parameters and experimental factors. However, we found that the Compton process is sensitive to Lambda_{NC} values roughly twice as large as those accessible to the pair production process.Comment: 24 pages, 11 eps figure files, RevTeX forma

Signals for Non-Commutative Interactions at Linear Colliders

Recent theoretical results have demonstrated that non-commutative geometries naturally appear within the context of string/M-theory. One consequence of this possibility is that QED takes on a non-abelian nature due to the introduction of 3- and 4-point functions. In addition, each QED vertex acquires a momentum dependent phase factor. We parameterize the effects of non-commutative space-time co-ordinates and show that they lead to observable signatures in several $2\to 2$ QED processes in $e^+e^-$ collisions. In particular, we examine pair annihilation, Moller and Bhabha scattering, as well as $\gamma\gamma\to\gamma\gamma$ scattering and show that non-commutative scales of order a TeV can be probed at high energy linear colliders.Comment: 51 pages, 23 figures, typos corrected, figure and references adde

A deep near infrared survey along the Norma Wall

Includes bibliographical references (leaves 192-197).The multi-wavelength surveys have improved our understanding of the extent and shape of the Norma Wall. However, the most central part of the Norma Wall remains poorly understood because of the high levels of extinction and star-crowding at these low Galactic latitudes. In this thesis, I present an imaging survey in the three near-infrared bands (J, H, Ks) along the most obscured part of the Norma Wall, the so called Norma Wall Survey (NWS). It has the goal to uncover the galaxy distribution in this area. The near-infrared waveband was selected because it is less affected by dust extinction than the optical. In addition, near-infrared surveys are sensitive to early-type galaxies which are better tracers of the mass in galaxies

Role of Soluble FMS-Like Tyrosine Kinase (SFLT-1) /Placental Growth Factor (Plgf) Ratio as Prognostic Marker for Cases of Preeclampsia

Objective: The aim of this study is to identify the role of sFlt-1/PIGF ratio as a prognostic marker for cases of preeclampsia.&nbsp;Patients and methods: The current study is a case control study that was conducted over 90 cases of primigravida patients, 24-34 weeks of gestation, randomly selected patients from outpatient clinic and ER of Ain Shams Maternity Hospital, they were classified into two groups, first group is preeclampsia group which was 45 preeclamptic pregnancies (preeclampsia patients and cases with severe criteria) and the second group was control group which was 45 normal pregnancies. Each patient was examined by sFlt-1/ PlGF ratio immunoassay kits.&nbsp;Results: In our study we have found that there was statistically significant positive correlation between the sFlt-1/PlGF ratio and blood pressure in 24-34 weeks. The correlations between the sFlt-1/ PlGF ratio and other laboratory markers were statistically significant as well. In the 24-34 weeks PE group, AST, ALT were positive meanwhile Platelet count yielded only a highly signifi cant negative correlation to the sFlt-1/PlGF ratio. We analyzed the time to delivery in all 45 patients with PE/HELLP within 2 days (24 patients), 2-7 days (10 patients), and later than 7 days (11 patients). Patients with interval to delivery within 2 days showed a higher sFlt-1/PlGF ratio, the sFlt-1/PlGF ratio in patients delivering within 2 days was (610.85). Patients with interval to delivery within 2-7 days exhibited a sFlt-1/PlGF ratio of (499.7). However, patients delivered later than 7 days had a sFlt-1/PlGF ratio of (230.43). For all PE/HELLP patients group (24-34 weeks), a sFlt-1/PlGF ratio greater than 590.1 (413.7 – 611.1) is associated with an 11.577 folds increased risk for an immediate occurence of delivery. The current study has found that the best cut off point after applying ROC curve between control group and cases group regarding soluble fms like tyrosine kinase/placental growth factor ratio was (&gt; 85) which gave us sensitivity of 100%, specificity of 100% and accuracy of 100%.Conclusion: We concluded from our study that the important clinical implication for the use of the sFlt-1/PlGF ratio for diagnosis, differential diagnosis, and risk stratification in PE/HELLP patients. Patients with sFlt-1/PlGF ratio above the level of 85 were preeclamptic and should be monitered for upcoming complications, symptoms and signs of severity. It could be used as a prognostic tool regarding maternal and fetal outcomes for patients with Preeclampsia between 24-34 weeks of gestation and patients at risk of having PE.</p