Smooth crossing of wΛ=−1w_{\Lambda} = -1 line in a single scalar field model

Smooth double crossing of the phantom divide line $w_{\Lambda}=-1$ has been found possible with a single minimally coupled scalar field for the most simple form of generalized k-essence cosmological model, in the presence of background cold dark matter. Such crossing is a sufficiently late time transient phenomena and does not have any pathological behaviour.Comment: 9 pages, 6 figure

Glass transition in Ultrathin Polymer Films : A Thermal Expansion Study

Glass transition process gets affected in ultrathin films having thickness comparable to the size of the molecules. We observe systematic broadening of glass transition temperature (Tg) as the thickness of the polymer film reduces below the radius of gyration but the change in the average Tg was found to be very small. Existence of reversible negative and positive thermal expansion below and above Tg increased the sensitivity of our thickness measurements performed using energy dispersive x-ray reflectivity. A simple model of Tg variation as a function of depth expected from sliding motion could explain the results. We observe clear glass transition even for 4 nm polystyrene film that was predicted to be absent from ellipsometry measurements of thicker films.Comment: 11 pages, 5 figure

Inflation is the generic feature of phantom field-not the big-rip

A class of solutions for phantom field corresponding to a generalized k-essence lagrangian has been presented, employing a simple method which provides the scope to explore many such. All the solutions having dynamical state parameter are found to touch the magic line w = -1, asymptotically. The solutions with constant equation of state can represent phantom, quitessence or an ordinary scalar field cosmologies depending on the choice of a couple of parameters of the theory. For w approximately equal to -1, quintessence and phantom models are indistinguishable through the Hubble parameter. Finally, inflation rather than big-rip has been found to be the generic feature of phantom cosmology.Comment: 8 pages, 3 figure

Effect of disorder on the electronic properties of graphene: a theoretical approach

In order to manipulate the properties of graphene, its very important to understand the electronic structure in presence of disorder. We investigate, within a tight-binding description, the effects of disorder in the on-site (diagonal disorder) term in the Hamiltonian as well as in the hopping integral (off-diagonal disorder) on the electronic dispersion and density of states by augmented space recursion method. Extrinsic off-diagonal disorder is shown to have dramatic effects on the two-dimensional Dirac-cone, including asymmetries in the band structures as well as the presence of discontinuous bands in certain limits. Disorder-induced broadening, related to the scattering length (or life-time) of electrons, is modified significantly with the increasing strength of disorder. We propose that our theory is suitable to study the effects of disorder in other 2D materials, e.g., a boron nitride monolayer.Comment: 11 pages, 8 figure

Dual nature of improper ferroelectricity in a magnetoelectric multiferroic

Using first principles calculations, we study the microscopic origin of ferroelectricity (FE) induced by magnetic order in the orthorhombic HoMnO3. We obtain the largest ferroelectric polarization observed in the whole class of improper magnetic ferroelectrics to date. We find that the two proposed mechanisms for FE in multiferroics, lattice- and electronic-based, are simultaneously active in this compound: a large portion of the ferroelectric polarization arises due to quantum-mechanical effects of electron orbital polarization, in addition to the conventional polar atomic displacements. An interesting mechanism for switching the magnetoelectric domains by an electric field via a 180-degree coherent rotation of Mn spins is also proposed.Comment: 6 pages, 4 figures. Submitted for publicatio

Adaptive action learning: a refusal to define

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Comparison of risk of abdominal hysterectomy versus myomectomy in the management of uterine fibroids: a comparative study

Background: The incidence of leiomyomas ranges from 20 to 25% in women aged 30 years and above. Gynaecologists prefer abdominal hysterectomy over myomectomy due to a reported recurrence rate of 10% during a 5 year follow-up period.  This study aimed to explore the differences in risk between abdominal myomectomy and hysterectomy in treatment of uterine fibroids.Methods: The study was conducted at the department of obstetrics and gynaecology in a tertiary care hospital at puducherry during April 2016 by retrospective analysis of past records like patient charts and operative notes of myomectomies and hysterectomies conducted during the period of May 2013 to March 2016. Those abdominal hysterectomies and myomectomies done for uterine fibroids were included for the study.Results: The study included a total of 145 subjects, 43 among them underwent abdominal myomectomy and 102 underwent total abdominal hysterectomy. There was a significant difference in age (p<0.001) and parity (p<0.001) between the two groups. Most of the anthropometric, intra-operative and post-operative parameters were not much different between the myomectomy and hysterectomy groups.Conclusions: Myomectomy can be preferred over hysterectomy for managing uterine fibroids in young nulliparous and primiparous women who want to preserve their fertility for a pregnancy in the near future, as there is no significant difference in the intra/post-operative morbidity between the two surgeries