The suppression of magnetism and the development of superconductivity within the collapsed tetragonal phase of Ca0.67Sr0.33Fe2As2 at high pressure

Structural and electronic characterization of (Ca0.67Sr0.33)Fe2As2 has been performed as a func- tion of pressure up to 12 GPa using conventional and designer diamond anvil cells. The compound (Ca0.67Sr0.33)Fe2As2 behaves intermediate between its end members-CaFe2As2 and SrFe2As2- displaying a suppression of magnetism and the onset of superconductivity. Like other members of the AEFe2As2 family, (Ca0.67Sr0.33)Fe2As2 undergoes a pressure-induced isostructural volume collapse, which we associate with the development of As-As bonding across the mirror plane of the structure. This collapsed tetragonal phase abruptly cuts off the magnetic state, giving rise to superconductivity with a maximum Tc=22.2 K. The maximum Tc of the superconducting phase is not strongly correlated with any structural parameter, but its proximity to the abrupt suppression of magnetism as well as the volume collapse transition suggests that magnetic interactions and structural inhomogeneity may play a role in its development. The pressure-dependent evolution of the ordered states and crystal structures in (Ca,Sr)Fe2As2 provides an avenue to understand the generic behavior of the other members of the AEFe2As2 family.Comment: 9 pages, 9 figure

Nonlinear Formations and Improved Randomized Approximation Algorithms for Multiway and Multicut Problems

We introduce nonlinear formulations of the multiway cut and multicut problems. By simple linearizations of these formulations we derive several well known formulations and valid inequalities as well as several new ones. Through these formulations we establish a connection between the multiway cut and the maximum weighted independent set problem that leads to the study of the tightness of several LP formulations for the multiway cut problem through the theory of perfect graphs. We also introduce a new randomized rounding argument to study the worst case bound of these formulations, obtaining a new bound of 2a(H)(1 - ) for the multicut problem, where ac(H) is the size of a maximum independent set in the demand graph H

Analyzing indications for caesarean delivery in a tertiary care facility in India by Robsons Ten Group Classification System: journey to reduce maternal mortality-audit caesarean rates: a prospective observational design

Background: Rising caesarean rates pose a challenge to obstetricians, the healthcare system, and the national economy. High rate of caesarean without clear evidence of a decrease in maternal and neonatal morbidity is matter of concern. The era of impatient obstetricians, and caesareans on demand are major contributing factors. The purpose of this study is to validateTGCS classification for indications of caesarean. This would help to audit and streamline the indications of caesarean. Standardization of indications is the need of the hour. Learning from what has happened in background of local situations is the main aim of this work. Methods: In a prospective observational design, 1140 women who underwent caesarean for varied indications in C R Gardi Hospital Ujjain were recruited. Patients were classified according to Robson’s Ten Group Classification System. Every woman was observed for post-cesarean morbidities like wound dehiscence, anemia, postpartum hemorrhage, and puerperal sepsis. Neonates were observed for NICU admission, low birth weight, prematurity, respiratory distress syndrome, meconium aspiration syndrome, and death. Chi- Square and student t test were used for analysis. Results: 45.8% of women were of group 5. Modifiable indications were 60.2% in the primary caesarean of group 5. PPH, puerperal sepsis, PNC anemia, wound dehiscence, DVT, rupture uterus and NICU admission, respiratory distress syndrome of neonates were significantly high in group 5 ( p= less than 0.05). Conclusions: Out of all caesarean 45.8% are second caesarean for previous one caesarean. PPH, puerperal sepsis, wound dehiscence and PNC anemia are significantly high in group 5

Pressure-induced superconductivity in the giant Rashba system BiTeI

At ambient pressure, BiTeI is the first material found to exhibit a giant Rashba splitting of the bulk electronic bands. At low pressures, BiTeI undergoes a transition from trivial insulator to topological insulator. At still higher pressures, two structural transitions are known to occur. We have carried out a series of electrical resistivity and AC magnetic susceptibility measurements on BiTeI at pressure up to ~40 GPa in an effort to characterize the properties of the high-pressure phases. A previous calculation found that the high-pressure orthorhombic P4/nmm structure BiTeI is a metal. We find that this structure is superconducting with Tc values as high as 6 K. AC magnetic susceptibility measurements support the bulk nature of the superconductivity. Using electronic structure and phonon calculations, we compute Tc and find that our data is consistent with phonon-mediated superconductivity.Comment: 7 pages, 7 figure