Validating delta-filters for resonant bar detectors of improved bandwidth foreseeing the future coincidence with interferometers

The classical delta filters used in the current resonant bar experiments for detecting GW bursts are viable when the bandwidth of resonant bars is few Hz. In that case, the incoming GW burst is likely to be viewed as an impulsive signal in a very narrow frequency window. After making improvements in the read-out with new transducers and high sensitivity dc-SQUID, the Explorer-Nautilus have improved the bandwidth ($\sim 20$ Hz) at the sensitivity level of $10^{-20}/\sqrt{Hz}$. Thus, it is necessary to reassess this assumption of delta-like signals while building filters in the resonant bars as the filtered output crucially depends on the shape of the waveform. This is presented with an example of GW signals -- stellar quasi-normal modes, by estimating the loss in SNR and the error in the timing, when the GW signal is filtered with the delta filter as compared to the optimal filter.Comment: 7 pages, presented in Amaldi6, accepted for publication in Journal of Physics: Conference Serie

Mean field analysis of quantum phase transitions in a periodic optical superlattice

In this paper we analyze the various phases exhibited by a system of ultracold bosons in a periodic optical superlattice using the mean field decoupling approximation. We investigate for a wide range of commensurate and incommensurate densities. We find the gapless superfluid phase, the gapped Mott insulator phase, and gapped insulator phases with distinct density wave orders.Comment: 6 pages, 7 figures, 4 table

Calculation of Weibull strength parameters and Batdorf flow-density constants for volume- and surface-flaw-induced fracture in ceramics

The calculation of shape and scale parameters of the two-parameter Weibull distribution is described using the least-squares analysis and maximum likelihood methods for volume- and surface-flaw-induced fracture in ceramics with complete and censored samples. Detailed procedures are given for evaluating 90 percent confidence intervals for maximum likelihood estimates of shape and scale parameters, the unbiased estimates of the shape parameters, and the Weibull mean values and corresponding standard deviations. Furthermore, the necessary steps are described for detecting outliers and for calculating the Kolmogorov-Smirnov and the Anderson-Darling goodness-of-fit statistics and 90 percent confidence bands about the Weibull distribution. It also shows how to calculate the Batdorf flaw-density constants by uing the Weibull distribution statistical parameters. The techniques described were verified with several example problems, from the open literature, and were coded. The techniques described were verified with several example problems from the open literature, and were coded in the Structural Ceramics Analysis and Reliability Evaluation (SCARE) design program

Radiation Pressure Induced Instabilities in Laser Interferometric Detectors of Gravitational Waves

The large scale interferometric gravitational wave detectors consist of Fabry-Perot cavities operating at very high powers ranging from tens of kW to MW for next generations. The high powers may result in several nonlinear effects which would affect the performance of the detector. In this paper, we investigate the effects of radiation pressure, which tend to displace the mirrors from their resonant position resulting in the detuning of the cavity. We observe a remarkable effect, namely, that the freely hanging mirrors gain energy continuously and swing with increasing amplitude. It is found that the `time delay', that is, the time taken for the field to adjust to its instantaneous equilibrium value, when the mirrors are in motion, is responsible for this effect. This effect is likely to be important in the optimal operation of the full-scale interferometers such as VIRGO and LIGO.Comment: 27 pages, 11 figures, RevTex styl

Quantum Phases of Ultracold Bosonic Atoms in a One Dimensional Optical Superlattice

We analyze various quantum phases of ultracold bosonic atoms in a periodic one dimensional optical superlattice. Our studies have been performed using the finite size density matrix renormalization group (FS-DMRG) method in the framework of the Bose-Hubbard model. Calculations have been carried out for a wide range of densities and the energy shifts due to the superlattice potential. At commensurate fillings, we find the Mott insulator and the superfluid phases as well as Mott insulators induced by the superlattice. At a particular incommensurate density, the system is found to be in the superfluid phase coexisting with density oscillations for a certain range of parameters of the system.Comment: 7 pages, 11 figure

Hardcore bosons in a zig-zag optical superlattice

We study a system of hard-core bosons at half-filling in a one-dimensional optical superlattice. The bosons are allowed to hop to nearest and next-nearest neighbor sites producing a zig-zag geometry and we obtain the ground state phase diagram as a function of microscopic parameters using the finite-size density matrix renormalization group (FS-DMRG) method. Depending on the sign of the next-nearest neighbor hopping and the strength of the superlattice potential the system exhibits three different phases, namely the bond-order (BO) solid, the superlattice induced Mott insulator (SLMI) and the superfluid (SF) phase. When the signs of both hopping amplitudes are the same (the "unfrustrated" case), the system undergoes a transition from the SF to the SLMI at a non-zero value of the superlattice potential. On the other hand, when the two amplitudes differ in sign (the "frustrated" case), the SF is unstable to switching on a superlattice potential and also exists only up to a finite value of the next nearest neighbor hopping. This part of the phase diagram is dominated by the BO phase which breaks translation symmetry spontaneously even in the absence of the superlattice potential and can thus be characterized by a bond order parameter. The transition from BO to SLMI appears to be first order.Comment: 6 pages, 11 figure

Is low amniotic fluid index an indicator of fetal distress and hence delivery?

Background: Amniotic fluid Index (AFI) is an indicator of fetal well-being. Low AFI is considered to be one of the indications for delivery as it may be associated with fetal distress and birth asphyxia. We sought to determine whether low AFI is an indicator of fetal compromise and an indication to deliver.Methods: This prospective, observational study was conducted at Department of Obstetrics & Gynecology, KMC, Manipal University, India, between August 2013 and Aug 2014. A total of 150 subjects that had induced labor or direct caesarean section for various indications and also having low-normal (5-8) / low (<5) AFI, were recruited. Subjects with fetal anomalies were excluded. Outcome variables studied were, fetal distress in labor, thick meconium stained amniotic fluid, mode of delivery in induced labor, perinatal asphyxia, and respiratory distress syndrome.Results: Out of 150 subjects, 68 (45.4%) had low and 82 (54.6%) had low-normal AFI. Both the groups were matched for demographic characteristics and confounding factors for neonatal outcome. In low AFI group the incidence of Low APGAR (11.7%), perinatal asphyxia (11.7%) and RDS (16.1%) were significantly higher compared to those in low-normal group (3.6%, 1.2% and 2.4% respectively) p = 0.057, 0.006 and 0.002. There was no significant difference between the groups with respect to mode of delivery when labor was induced.Conclusions: Low AFI, especially when it is <5, is an indicator of fetal compromise and one may anticipate perinatal asphyxia and RDS. Hence it is prudent to contemplate delivery when the AFI is between 5 and 8

Supersolid and solitonic phases in one-dimensional Extended Bose-Hubbard model

We report our findings on quantum phase transitions in cold bosonic atoms in a one dimensional optical lattice using the finite size density matrix renormalization group method in the framework of the extended Bose-Hubbard model. We consider wide ranges of values for the filling factors and the nearest neighbor interactions. At commensurate fillings, we obtain two different types of charge density wave phases and a Mott insulator phase. However, departure from commensurate fillings yield the exotic supersolid phase where both the crystalline and the superfluid orders coexist. In addition, we obtain signatures for solitary waves and also superfluidity.Comment: 7 pages, 11 figure