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Exploration wells are liquid-filled boreholes drilled into formations with different geophysical and petrophysical properties. These boreholes support axisymmetric, flexural, and quadrupole family of guided modes that can probe radially varying formation properties at different frequencies. Radially varying formation properties are caused by drilling-induced fractures or near-wellbore stress concentrations. This work describes a novel workflow that inverts borehole flexural and Stoneley dispersions to obtain radially varying formation mass density and shear and bulk moduli away from the borehole surface. An integral equation relates fractional changes in guided mode velocities at different frequencies caused by fractional changes in radially varying mass density and shear and bulk moduli from a radially uniform reference state. A solution of this integral equation is based on extending the Backus–Gilbert (B–G) method for obtaining radial profile of a single to radial profiles of three formation properties away from the borehole surface. Inverted radial profiles from synthetic flexural and Stoneley dispersions have been validated against input formation parameters used to generate synthetic (measured) dispersions. [ABSTRACT FROM AUTHOR]

Abstract Quark nuggets, relics of a first order phase transition, from quarks to hadrons, microseconds after the big bang; the core of the neutron star, and the colour entangled quarks, prior to the phase transition, are possible candidates of the cosmic quarks. [ABSTRACT FROM AUTHOR]

This paper describes an exhaustive study of the variations of the mean force sensitivity coefficients in the entire region of crystalline langasite (LGS). We also study the variation of temperature coefficients in the entire region of the crystalline LGS and its isomorphs. The computational results have been obtained from a procedure that has been successfully employed in the study of the planar and temperature stressinduced frequency shifts in thickness-mode resonators. Both the fast and slow thickness-shear modes have been studied. Among other things, the loci of orientations with zero stress and temperature coefficients of frequency have been identified for LGS. [ABSTRACT FROM PUBLISHER]

It is entirely plausible under reasonable conditions, that a first-order QCD phase transition occurred from quarks to hadrons when the universe was about a microsecond old. Relics, if there be any, after the quark-hadron phase transition are the most deciding signatures of the phase transition. It is shown in this paper that quark nuggets, the possible relics of first-order QCD phase transitions with baryon number larger than 1043 will survive the entire history of the universe up to now and can be considered as a candidate for the cold dark matter. The spin down core of the neutron star on the high density low temperature end of the QCD phase diagram initiates transition from hadrons to quarks. As the star spins down, the size of the core goes on increasing. Recently discovered massive Pulsar PSRJ 1614-2230 with a mass of 1.97 ± 0.04M⊙ most likely has a strongly interacting core. What possible observables can there be from these neutron stars? [ABSTRACT FROM AUTHOR]

In Israel-Stewart's second order hydrodynamics, the viscous effect of dilepton emission from a QGP medium is investigated. Dileptons are strongly affected by QGP viscosity. Large invariant mass dileptons, due to their lower velocity, are less affected by viscosity than the low invariant mass dileptons. [ABSTRACT FROM AUTHOR]

Abstract: We analyse the recently available experimental data on direct photon productions from Au+Au collisions at RHIC and from Pb+Pb collisions at LHC energies. The transverse momentum () distributions have been evaluated with the assumption of an initial quark gluon plasma phase at energy densities and 70 GeV/fm3 with initial thermalisation times and 1.0 fm/c respectively for RHIC and LHC energies. The theoretical evaluations agree well with the experimental observations. The thermal radiations dominate within the range . The ratio of thermal photons to dileptons () determines more precisely the window, as mentioned above. [Copyright &y& Elsevier]

The proposed international Facility for Antiproton and Ion Research (FAIR) at GSI-Darmstadt, will be a source of exotic radionuclidic beam and is expected to be operational in 2016. The facility will deliver 2 GeV/u to 45 GeV/u beam covering the entire range of the periodic table with the intensities three orders of magnitude higher than that available anywhere in the world today. This facility will serve all areas of fundamental sciences including nuclear physics, physics at extreme density conditions like neutron stars, plasma and laser physics, hadron physics and applied areas in chemistry, biology and material sciences. In this article, we discuss briefly the FAIR facility, with special emphasis on Indian participation. [ABSTRACT FROM AUTHOR]

We simulate direct photon production in the evolution of viscous quark-gluon plasma medium. Photons from Compton and annihilation processes are considered. The viscous effect on photon production is very strong and reliable simulation is possible only in a limited PT range. For minimally viscous fluid (η/s=0.08), direct photons can be reliably computed only up to pT⩽1.3 GeV. With reduced viscosity (η/s=0.04), the limit increases to pT⩽2 GeV. [ABSTRACT FROM AUTHOR]

This paper presents a perturbation model to obtain flexural mode dispersions of noncircular fluid-filled boreholes in homogeneous elastic formations. The perturbation model is based on Hamilton’s principle with a modified procedure for the reference state selection in order to handle the directional sensitivity of the flexural modes. The accuracy of the perturbation model has been confirmed by comparison to boundary integral solutions. Numerical results confirm that for a fast formation, even modes, and for a slow formation, odd modes are more sensitive to changes in the borehole elongation and azimuth. Even though the focus of this work is on elliptical boreholes and breakouts, the formulation is valid for any kind of noncircular borehole. [ABSTRACT FROM AUTHOR]

No abstract received. [ABSTRACT FROM AUTHOR]

Sonic techniques in geophysical prospecting involve elastic wave velocity measurements that are performed by placing acoustic transmitters and receivers in a fluid-filled borehole. The signals recorded at the receivers are processed to obtain compressional- and shear-wave velocities in the surrounding formation. These velocities are generally used in seismic surveys for the time-to-depth conversion and other formation parameters, such as porosity and lithology. Depending upon the type of transmitter used (e.g. monopole or dipole) and as a result of eccentering, it is possible to excite axisymmetric , flexural and quadrupole families of modes propagating along the borehole. We present a study of various propagating and leaky modes that includes their dispersion and attenuation characteristics caused by radiation into the surrounding formation. A knowledge of propagation characteristics of borehole modes helps in a proper selection of transmitter bandwidth for suppressing unwanted modes that create problems in the inversion for the compressional- and shear-wave velocities from the dispersive arrivals. It also helps in the design of a transmitter for a preferential excitation of a given mode in order to reduce interference with drill-collar or drilling noise for sonic measurements-while-drilling. Computational results for the axisymmetric family of modes in a fast formation with a shear-wave velocity of 2032 m/s show the existence of Stoneley, pseudo-Rayleigh and anharmonic cut-off modes. In a slow formation with a shear-wave velocity of 508 m/s, we find the existence of the Stoneley mode and the first leaky compressional mode which cuts in at approximately the same normalized frequency ( a is the borehole radius) as that of the fast formation. The corresponding modes among the flexural family include the lowest-order flexural and anharmonic cut-off modes. For both the fast and slow formations, the first anharmonic mode cuts in at a normalized frequency approximately. Cut-off frequencies of anharmonic modes are inversely proportional to the borehole radius in the absence of any tool. The borehole quadrupole mode can also be used for estimating formation shear slownesses. The radial depth of investigation with a quadrupole mode is marginally less than that of a flexural mode because of its higher frequency of excitation. [ABSTRACT FROM AUTHOR]

Reports on the use of doubly rotated contoured quartz resonators in the design of stable clocks and dual-mode sensors for measurement of pressure and temperature. Technique used to analyze the C-mode of a resonator; Computational results for harmonic and anharmonic overtones of several thickness modes of the resonators; Models used to calculate temperature and induced changes in resonant frequencies.

An International accelerator facility, known as the Facility for Antiproton and Ion Research (FAIR) is being built at Darmstadt, Germany. Equipped with unprecedented beam intensity, the facility will be used to perform experiments on the areas of nuclear physics, high energy physics, hadron physics, atomic and plasma physics apart from advanced research in accelerator technology. The facility will be built in collaboration with several countries including India and will be operational by 2017. [ABSTRACT FROM AUTHOR]

Continuous measurement of radon-222 concentration in soil was carried out across duration of one year at a geologically faulted area having high regional heat flow to detect anomalies caused by seismic activities. The data reveals a range of periodicities present in the radon time series. To identify seismic induced radon changes we treat the time series data through various filtering methods to remove inherent periodicities. The Ensemble Empirical Mode Decomposition (EEMD) is deployed to decompose the signal into its characteristic modes. Hilbert Huang Transform (HHT) is applied for the first time on the physically significant modes obtained by EEMD to represent time–energy–frequency of the recorded soil radon time series. After removing the periodic and quasi-periodic constituents from the original time series, the simulated result shows a forceful correlation in recorded radon-222 anomalies with regional and local seismic events. [ABSTRACT FROM AUTHOR]

The problem of inferring unknown geometry and material parameters of a waveguide model from noisy samples of the associated modal dispersion curves is considered. In a significant reduction of the complexity of a common inversion methodology, the inner of two nested iterations is eliminated: The approach described does not employ explicit fitting of the data to computed dispersion curves. Instead, the unknown parameters are adjusted to minimize a cost function derived directly from the determinant of the boundary condition system matrix. This results in an efficient inversion scheme that, in the case of noise-free data, yields exact results. Multimode data can be simultaneously processed without extra complications. Furthermore, the inversion scheme can accommodate an arbitrary number of unknown parameters, provided that the data have sufficient sensitivity to these parameters. As an important application, we consider the sonic guidance condition for a fluid-filled borehole in an elastic, homogeneous, and isotropic rock formation for numerical forward and inverse dispersion analysis. We investigate numerically the parametric inversion with errors in the model parameters and the influence of bandwidth and noise, and examine the cases of multifrequency and multimode data, using simulated flexural and Stoneley dispersion data. [ABSTRACT FROM AUTHOR]

The main aim of the study is to present an evaluation of radon concentration in underground water of Bakreswar and Tantloi geothermal region which is mainly used for drinking purposes of the local people. Water samples were collected from tube-wells at 173 different locations. The radon (222Rn) concentration level was observed to fluctuate widely between 3.3 and 803.8 Bq/l with an average of 106.8 Bq/l. Nearly 42% of the samples had radon concentration above the safe limit of 100 Bq/l recommended by World Health Organisation (WHO) and European Union Commission (EU). Considering the WHO and International Commission on Radiological Protection recommended water consumption rate for adults (730 l/year) the corresponding total annual effective dose of the samples were estimated to assess the probable health risk. Total annual effective dose of the samples were varied between 16.72 and 4079.47 µSv/year with an average value of 541.92 µSv/year. About 95% samples exceed the WHO and EU Commission proposed safe limit of 100 µSv/year. [ABSTRACT FROM AUTHOR]

Present paper deals with a brief review of the research carried out to develop multi-parametric gas-geochemical monitoring facilities dedicated to earthquake prediction research in India by installing a network of seismo-geochemical monitoring observatories at different regions of the country. In an attempt to detect earthquake precursors, the concentrations of helium, argon, nitrogen, methane, radon-222 (Rn), polonium-218 (Po), and polonium-214 (Po) emanating from hydrothermal systems are monitored continuously and round the clock at these observatories. In this paper, we make a cross correlation study of a number of geochemical anomalies recorded at these observatories. With the data received from each of the above observatories we attempt to make a time series analysis to relate magnitude and epicentral distance locations through statistical methods, empirical formulations that relate the area of influence to earthquake scale. Application of the linear and nonlinear statistical techniques in the recorded geochemical data sets reveal a clear signature of long-range correlation in the data sets. [ABSTRACT FROM AUTHOR]

Piezoelectric materials are used in many applications in the oilfield services industry. Four illustrative examples are given in this paper: marine seismic survey, precision pressure measurement, sonic logging-while-drilling, and ultrasonic bore-hole imaging. In marine seismics, piezoelectric hydrophones are deployed on a massive scale in a relatively benign environment. Hence, unit cost and device reliability are major considerations. The remaining three applications take place downhole in a characteristically harsh environment with high temperature and high pressure among other factors. The number of piezoelectric devices involved is generally small but otherwise highly valued. The selection of piezoelectric materials is limited, and the devices have to be engineered to withstand the operating conditions. With the global demand for energy increasing in the foreseeable future, the search for hydrocarbon resources is reaching into deeper and hotter wells. There is, therefore, a continuing and pressing need for hightemperature and high-coupling piezoelectric materials. [ABSTRACT FROM AUTHOR]

The NA60 Collaboration has extracted the inverse slope parameters, Teff of the di-muon spectra originating from the In + In collisions at √SNN = 17.3 GeV for various invariant mass regions. They have observed that the inverse slope parameter as a function of invariant mass of the lepton pair drops beyond the ρ peak. In the present work, first we reproduce the observed invariant mass and transverse momentum spectra of the muon pairs by taking into account the medium effects on the hadronic spectral function. Then we show that the slope parameters extracted from the transverse momentum distributions for various invariant mass windows can be explained by assuming the formation of a partonic phase initially which reverts to the hadronic phase through a weak first-order phase transition at a temperature Tc ∼ 175 MeV. It is observed that a scenario without the formation of a partonic phase does not reproduce the nonmonotonic behavior of the inverse slope parameter nontypical of radial flow. [ABSTRACT FROM AUTHOR]

Abstract: Variations in the relative composition of constituent gases coming out of the mud volcano near Jarwa Creek in Baratang Island, Middle Andaman, are discussed on the basis of regional tectonic settings and seismo-geochemical features. The most abundant gas is CH4 (55.7vol.%) followed by N2 (32.2%), O2 +Ar (9.9%), CO2 (2.0%) and He (0.2%). Concentration of the radioactive gas 222Rn is relatively high (7500Bq/m3). This paper discusses the experimental methods adopted to continuously monitor He, CH4, CO2 and 222Rn with a view to identify pre-seismic gas concentration anomalies associated with regional seismic occurrences. Results related to this gas-geochemical monitoring are presented with a purpose to develop ability in ascribing a distinct geochemical anomaly to a particular seismic activity in the region. [Copyright &y& Elsevier]

This paper describes a new algorithm based on the spectral method for the computation of Stoneley wave dispersion and attenuation propagating in cylindrical structures composed of fluid, elastic and poroelastic layers. The spectral method is a numerical method which requires discretization of the structure along the radial axis using Chebyshev points. To approximate the differential operators of the underlying differential equations, we use spectral differentiation matrices. After discretizing equations of motion along the radial direction, we can solve the problem as a generalized algebraic eigenvalue problem. For a given frequency, calculated eigenvalues correspond to the wavenumbers of different modes. The advantage of this approach is that it can very efficiently analyse structures with complicated radial layering composed of different fluid, solid and poroelastic layers. This work summarizes the fundamental equations, followed by an outline of how they are implemented in the numerical spectral schema. The interface boundary conditions are then explained for fluid/porous, elastic/porous and porous interfaces. Finally, we discuss three examples from borehole acoustics. The first model is a fluid-filled borehole surrounded by a poroelastic formation. The second considers an additional elastic layer sandwiched between the borehole and the formation, and finally a model with radially increasing permeability is considered. [ABSTRACT FROM AUTHOR]

Abstract: 222Rn concentrations were measured in the bubble gases, spring waters, soil gases and in ambient air around the thermal springs at Bakreswar in West Bengal, India. This group of springs lies within a geothermal zone having exceptionally high heat flow about 230 mW/m2, resembling young oceanic ridges. The spring gas has a high radon activity (∼885 kBq/m3) and is rich in helium (∼1.4 vol. %) with appreciably large flow rate. The measured radon exhalation rates in the soils of the spring area show extensive variations from 831 to 4550/mBqm2 h while 222Rn concentrations in the different spring waters vary from 3.18 to 46.9 kBq/m3. Surface air at a radius of 40m around the springs, within which is situated the Bakreswar temple complex and a group of dwellings, has radon concentration between 450 and 500Bq/m3. In the present paper we assess the radon activity background in and around the spring area due to the different contributing sources and its possible effect on visiting pilgrims and the people who reside close to the springs. [Copyright &y& Elsevier]

Abstract: Temporal fluctuations of Rn-222 and Po-218 emanated from a thermal spring have been investigated. Nonlinear statistical approach has been employed to the time sequences as to bring out the ingrained structure of the experimental data and the underlying mechanism therein. It is observed that the irregular time series are nonrandom and consistent with the nonlinear process. In addition, our findings reveal that the experimental time dependent data bears the signature of chaotic traits. [Copyright &y& Elsevier]

A technique known as pressure swing adsorption (PSA) has been employed in a novel way to concentrate a lean amount of helium present in natural gas through selective physical elimination of N2, CO2, CH4 and C2+ (heavier hydrocarbons) in a stepwise cycle sequence at preset time intervals. The PSA-based helium pilot plant consists of four stages, with each stage composed of three parallel adsorber beds (vessels packed with adsorbents). The plant has been designed and operated for purifying helium to a level of better than 99.0 vol% from a feed natural gas containing helium to the tune of 0.06 vol%. The normal feed pressure range is 4-5 bar (abs). The overall recovery of the pilot plant is around 61%. The features of the PSA system are described here with a detailed description of the operating parameters of the helium pilot plant. [ABSTRACT FROM AUTHOR]

Abstract: An experimental station to monitor variations in radon and radon progeny concentrations in the gases from the thermal springs at Bakreswar, West Bengal, India has been installed. This is essentially a part of a continuous, automated, multi-parametric geochemical monitoring system (GMS) installed with a view to detect probable earthquake-related precursory changes in the spring gas emanations. The entire data acquisition system is computer driven and fully automated. Instrument readings acquired over a 24-h interval are transmitted through a tele-link facility from the field laboratory located at the thermal spring site situated about 250km away, once a day, to a workstation at our Centre in Kolkata for analysis and storage. After the system was installed during mid-December, 2004, concurrent anomalous changes in concentration profiles of 222Rn, 218Po and 214Bi occurred beyond 2 level four times during the period of present observation duration up to February 04, 2005. The monitored anomalies may be attributed to precursory dilatation responses arising due to earthquakes that had occurred subsequently in Indonesia and the Andaman and Nicobar Islands. The observed variations reveal evidence of pre-seismic radioactive heterogeneities in escaping subsurface fluids from the monitored thermal spring gases. [Copyright &y& Elsevier]

Abstract: An observation has been made of an explosive helium burst showing an anomalous concentration of helium of ∼61.6vol% compared to the ∼1.4vol% normally present in the thermal spring gas emanations at Bakreswar, West Bengal. This elevated level, along with deuterium ∼1.7vol%, has been observed for the first time in a gas chromatograph. Attempts have been made to correlate the observations, as a precursory signal, with some recent major tectonic disturbances. [Copyright &y& Elsevier]

Abstract: Recent astrophysical observations indicate that the universe is composed of a large amount of dark energy (DE) responsible for an accelerated expansion of the universe, along with a sizeable amount of cold dark matter (CDM), responsible for structure formation. At present, the explanations for the origin or the nature of both CDM and DE seem to require ideas beyond the standard model of elementary particle interactions. Here, for the first time, we show that CDM and DE can arise entirely from the standard principles of strong interaction physics and quantum entanglement. Quantitative agreement with the present data obtains without the need for any adjustable parameters. [Copyright &y& Elsevier]

Within the Corinth Rift Laboratory, dipole sonic data have been acquired in the AIG 10 well between depths 711 and 1004 m during three passes of a sonic logging tool at three different borehole fluid pressures. Specific sections of the well reveal clear characteristics of either moderate-to-large azimuthal anisotropy (9–25%) below the Aigion Fault, e.g., 779–784 and 809–816 m, with a fast-shear azimuth directed 105°, or homogeneous isotropic medium (i.e., 735–753 m) between the casing shoe and the fault. The presence of the fault is coincident with the identification of lower velocities over an interval of approximately 12–14 m. Analysis of the data reveals that the formation is not acoustically stress-sensitive to the 3 MPa differential pressure applied. Interpretation of the sonic data with complementary image logs suggests the anisotropy is due to intrinsic fractures and bedding, and the fast-shear direction 105° is consistent with the regional maximum horizontal stress. To cite this article: R. Prioul et al., C. R. Geoscience 336 (2004). [Copyright &y& Elsevier]

ABSTRACT The existence of compact gravitational lenses, with masses around 0.5 M[sub ⊙], has been reported in the halo of the Milky Way. The nature of these dark lenses is as yet obscure, particularly because these objects have masses well above the threshold for nuclear fusion. In this work, we show that they find a natural explanation as being the evolutionary product of the metastable false vacuum domains (the so-called strange quark nuggets) formed in a first order cosmic quark–hadron transition. [ABSTRACT FROM AUTHOR]

The space–time evolution of the hot and dense matter formed after the collisions of heavy nuclei at ultra-relativistic energies is investigated using (3+1)-dimensional hydrodynamical models. The effects of the spectral shift of the hadronic properties are incorporated in the equation of state (EOS) of the evolving matter. In-medium shift of hadronic properties are considered for Quantum Hadrodynamics (QHD) and universal scaling scenarios. It is found that the EOS for the hadronic matter for universal scaling of hadronic masses (except pseudoscalar) is similar to the recent lattice results. We observe that the space–time volume of the hadronic matter at the freeze-out is considerably different from the one when medium effects on the hadrons are ignored. The transverse mass spectra of pions and protons of the NA49 Collaboration are analyzed in the present framework. [Copyright &y& Elsevier]

A letter is presented which discusses a study that performs helium isotropic analyzes of volcanic plumes from the thermal springs at Tantloi in Jharkhand and Bakreswar in West Bengal, India.