Relationship between iron metabolism and thyroid hormone profile in hypothyroidism

Background: Iron and thyroid hormone metabolism are closely related with each other. Iron plays an important role for both the synthesis as well as metabolism of thyroid hormones acting as a component of many enzymes including thyroid peroxidase (TPO). So, iron deficiency can lead to abnormal functioning of thyroid gland. Ferritin is storage form of iron in our body. Several studies in showed that nutritional iron deficiency can significantly decrease the circulating levels of both T4 and T3 and it can also reduce peripheral conversion of T4 to T3. So, the aim of the study is to find out whether there is any relationship between hypothyroidism and iron metabolism.Methods: This cross-sectional descriptive study was conducted at Deben Mahata Government Medical College and Hospital, Purulia on 50 hypothyroid patients and 50 age and sex matched controls after imposing inclusion and exclusion criterias. Blood samples were collected and estimation of Serum TSH, fT4 and fT3, iron, ferritin and TIBC levels were done. Then the data obtained were analysed by proper statistical methods.Results: Out of 100 subjects 68 were male and rest were female. The mean serum TSH level in study population was significantly higher than that of comparison group. While serum fT3 and fT4 level in study group were lower than the control group and both were statistically significant. In the other hand, the mean serum ferritin and iron levels in cases were lower than that in controls and the mean TIBS was higher in study group and all the differences were statistically significant. There were significant correlation between Serum ferritin and serum iron (positive correlation), Serum ferritin and TSH (negative correlation), Serum TSH and fT4 (negative correlation) but there was no significant relationship between serum TSH and iron.Conclusions: The iron metabolism is disturbed in hypothyroidism reflected by low serum ferritin and iron

Large amplitude double layers in a four component dusty plasma with non-thermal ions

Dust acoustic double layers are studied in a four component dusty plasma. Positively and negatively charged mobile dust and Boltzmann distributed electrons are considered. The ion distribution is taken as nonthermal. The existence of compressive and rarefractive double layers is studied by pseudopotential approach. The effect of non-thermal ions on small amplitude and arbitrary amplitude double layers are also studied.Large amplitude double layers in a four component dusty plasma with non-thermal ions Gurudas Mandal1, Kaushik Roy2 and Prasanta Chatterjee2* 1Department of APCE, East West University, Mohakhali, Dhaka Bangladesh 2Department of Mathematics, Siksha Bhavana, Visva Bharati, Santiniketan-731 235, West Bengal, India E-mail : [email protected] of APCE, East West University, Mohakhali, Dhaka Bangladesh 2Department of Mathematics, Siksha Bhavana, Visva Bharati, Santiniketan-731 235, West Bengal, Indi

Unveiling the Dark Side

Discovery and characterisation of black holes (BHs), neutron stars (NSs), and white dwarfs (WDs) with detached luminous companions (LCs) in wide orbits are exciting because they are important test beds for dark remnant (DR) formation physics as well as binary stellar evolution models. Recently, 187 candidates have been identified from Gaia's non-single star catalog as wide orbit (P_orb > 45 days), detached binaries hosting DRs. We identify UV counterparts for 49 of these sources in the archival GALEX data. Modeling the observed spectral energy distribution (SED) spanning FUV-NUV to IR for these sources and stellar evolution models, we constrain the LC properties including mass, bolometric luminosity, and effective temperature for these 49 sources. Using the LC masses, and the astrometric mass function constrained by Gaia, we constrain the DR masses for these sources. We find that 9 have masses clearly in the NS or BH mass range. Fifteen sources exhibit significant NUV excess and 4 show excess both in FUV and NUV. The simplest explanation for these excess UV flux is that the DRs in these sources are white dwarfs (WDs). Using SED modeling we constrain the effective temperature and bolometric luminosity for these 15 sources. Our estimated DR masses for all of these 15 sources are lower than the Chandrasekhar mass limit for WDs. Interestingly, five of these sources had been wrongly identified as neutron stars in literature.Comment: 11 pages, 8 figures, 2 tables, comments welcom

Hunting Down White Dwarf--Main Sequence Binaries Using Multi-Wavelength Observations

Identification of white dwarfs (WD) with main-sequence (MS) companions and characterization of their properties can put important constraints on our understanding of binary stellar evolution and guide the theoretical predictions for a wide range of interesting transient events relevant for, e.g., LSST, ZTF, and LISA. In this study, we combine ultraviolet (UV) and optical color-magnitude diagrams (CMDs) to identify unresolved WD--MS binaries. In particular, we combine high-precision astrometric and photometric data in the optical from \gaia\ -DR3 and UV data from GALEX GR6/7 to identify 111 WD--MS candidates within 100 pc. Of these, 92 are newly identified. Using the Virtual Observatory SED Analyzer (VOSA) we fit the spectral energy distributions (SEDs) of all our candidates and derive stellar parameters, such as effective temperature, bolometric luminosity, and radius for both companions. We find that our identification method helps identify hotter and smaller WD companions (majority with $\geq$10,000 K and $\leq$0.02 $R_\odot$) relative to the WDs identified by past surveys. We infer that these WDs are relatively more massive ($>0.3 M_\odot$). We find that most of the MS companions in our binaries are of the $K$ and $M$ spectral types.Comment: 11 pages, 7 figures, one table, Submitted to MNRAS journa

Speed and Shape of Electrostatic Waves in Dust-Ion Plasma

Nonlinear dust acoustic waves are studied in a magnetized plasma. Quasineutrality is considered. The existence of a soliton solution is determined by a pseudo-potential approach. Sagdeev's potential is obtained in terms of U(= αu dx + γu dz ), the component of the dust-ion velocity in the direction of the propagation of the wave. It is shown that there exists a critical value of U, beyond which the solitary waves cease to exist

Shock Waves in a Dusty Plasma with Positive and Negative Dust where Ions are Non-Thermal

A four-component dusty plasma consisting of electrons, ions, and negatively as well as positively charged dust grains has been considered. Shock waves may exist in such a four-component dusty plasma. The basic characteristics of shock waves have been theoretically investigated by employing reductive perturbation technique (RPT). It is found that negative as well as positive shock potentials are present in such dusty plasma. The present results may be useful for understanding the existence of nonlinear potential structures that are observed in different regions of space (viz. cometary tails, lower and upper mesosphere, Jupiter's magnetosphere, interstellar media, etc)