Strong field gravitational lensing in scalar tensor theories

Strong field gravitational lensing in the Brans-Dicke theory has been studied. The deflection angle for photons passing very close to the photon sphere is estimated for the static spherically symmetric space-time of the theory and the position and magnification of the relativistic images are obtained. Modeling the super massive central object of the galaxy by the Brans-Dicke space-time, numerical values of different strong lensing observable are estimated. It is found that against the expectation there is no significant scalar field effect in the strong field observable lensing parameters. This observation raises question on the potentiality of the strong field lensing to discriminate different gravitational theories.Comment: 20 pages, accepted in Class. Quantum Grav., final versio

Testing gravity at the Second post-Newtonian level through gravitational deflection of massive particles

Expression for second post-Newtonian level gravitational deflection angle of massive particles is obtained in a model independent framework. Several of its important implications including the possibility of testing gravitational theories at that level are discussed.Comment: 5 pages, couple of equations of the previous version are correcte

Analogue Of The Fizeau Effect In An Effective Optical Medium

Using a new approach, we propose an analogue of the Fizeau effect for massive and massless particles in an effective optical medium derived from the static, spherically symmetric gravitational field. The medium is naturally perceived as a dispersive medium by matter de Broglie waves. Several Fresnel drag coefficients are worked out, with appropriate interpretations of the wavelengths used. In two cases, it turns out that the coefficients become independent of the wavelength even if the equivalent medium itself is dispersive. A few conceptual issues are also addressed in the process of derivation. It is shown that some of our results complement recent work dealing with real fluid or optical black holes

Design and Test of a Forward Neutron Calorimeter for the ZEUS Experiment

A lead scintillator sandwich sampling calorimeter has been installed in the HERA tunnel 105.6 m from the central ZEUS detector in the proton beam direction. It is designed to measure the energy and scattering angle of neutrons produced in charge exchange ep collisions. Before installation the calorimeter was tested and calibrated in the H6 beam at CERN where 120 GeV electrons, muons, pions and protons were made incident on the calorimeter. In addition, the spectrum of fast neutrons from charge exchange proton-lucite collisions was measured. The design and construction of the calorimeter is described, and the results of the CERN test reported. Special attention is paid to the measurement of shower position, shower width, and the separation of electromagnetic showers from hadronic showers. The overall energy scale as determined from the energy spectrum of charge exchange neutrons is compared to that obtained from direct beam hadrons.Comment: 45 pages, 22 Encapsulated Postscript figures, submitted to Nuclear Instruments and Method

Wormhole with varying cosmological constant

It has been suggested that the cosmological constant is a variable dynamical quantity. A class of solution has been presented for the spherically symmetric space time describing wormholes by assuming the erstwhile cosmological constant $\Lambda$ to be a space variable scalar, viz., $\Lambda$ = $\Lambda (r)$ . It is shown that the Averaged Null Energy Condition (ANEC) violating exotic matter can be made arbitrarily small.Comment: 8 pages, 2 figures, Accepted in Gen. Rel. Gra

Region of Excessive Flux of PeV Cosmic Rays in the Direction Toward Pulsars PSR J1840+5640 and LAT PSR J1836+5925

An analysis of arrival directions of extensive air showers (EAS) registered with the EAS MSU and EAS-1000 prototype arrays has revealed a region of excessive flux of PeV cosmic rays in the direction toward pulsars PSR J1840+5640 and LAT PSR J1836+5925 at significance level up to 4.5sigma. The first of the pulsars was discovered almost 30 years ago and is a well-studied old radio pulsar located at the distance of 1.7pc from the Solar system. The second pulsar belongs to a new type of pulsars, discovered by the space gamma-ray observatory Fermi, pulsations of which are not observed in optical and radio wavelengths but only in the gamma-ray range of energies (gamma-ray-only pulsars). In our opinion, the existence of the region of excessive flux of cosmic rays registered with two different arrays provides a strong evidence that isolated pulsars can give a noticeable contribution to the flux of Galactic cosmic rays in the PeV energy range.Comment: 14 pages; v.2: a few remarks to match a version accepted for Astronomy Letters added. They can be found by redefining the \NEW command in the preamble of the LaTeX fil

Modeling the Compressibility Behavior of Hard Red Wheat Varieties

Citation: Turner A., M. Montross, S.G. McNeill, M.P. Sama, M.E. Casada, J.M. Boac, R. Bhadra, R.G. Maghirang, and S.A. Thompson. Modeling the compressibility behavior of hard red wheat varieties. 2016. Transaction of ASABE 59(3): 1029-10385.The bulk density of grain in a storage structure varies vertically and horizontally due to the overburden pressure created by the cumulative weight of the overlying material. As the overburden pressure increases, the stored material compacts. This compaction is believed to be caused by rearrangement of kernels along with higher intergranular stress between particles, leading to kernel deformation. This compaction is of primary concern when estimating the amount of grain in a storage structure. In this comprehensive study, confined uniaxial compression tests were conducted on 27 different samples of hard red winter wheat, at three moisture levels, over the range of pressures typically encountered in storage structures (0 to 138 kPa). Mathematical models using the prior, modified, and new forms of the bulk density equation were evaluated to describe the resulting pressure-density relationship as a function of moisture content. With the new data set, the modified version of the Page equation had the lowest root mean square error (RMSE) of 4.7 kg m-3, while the other equations, including the original polynomial equation used in the WPACKING program, had RMSEs between 6.0 and 7.1 kg m-3. The models were validated using previously published compressibility data and the root mean square prediction error was determined to vary from 8.1 to 13.4 kg m-3. Four of the best performing models were subsequently applied to field measurements from 35 concrete and 16 steel bins. When applied to the field data a slight bias was observed in steel and concrete bins, but several of the models, including the modified Page and polynomial models, produced an average error of less than 2% from the measured grain mass

Stored Grain Pack Factors for Wheat: Comparison of Three Methods to Field Measurements

Storing grain in bulk storage units results in grain packing from overbearing pressure, which increases grain bulk density and storage unit capacity. This study compared pack factors of hard red winter (HRW) wheat in vertical storage bins using different methods: the existing packing model (WPACKING), the USDA Risk Management Agency (RMA) method, and the USDA Farm Service Agency Warehouse Licensing and Examination Division (FSA-W) method. Grain bins containing HRW wheat were measured in Kansas, Oklahoma, and Texas. Packing was measured in corrugated steel bins and reinforced concrete bins with diameters ranging from 4.6 to 31.9 m (15.0 to 104.6 ft) and equivalent level grain heights ranging from 4.1 to 41.6 m (13.4 to 136.6 ft). The predicted masses of compacted stored wheat based on WPACKING, RMA, and FSA-W were compared to the reported mass from scale tickets. Pack factors predicted by WPACKING ranged from 0.929 to 1.073 for steel bins and from 0.986 to 1.077 for concrete bins. Pack factors predicted by the RMA method ranged from 0.991 to 1.157 for steel bins and from 0.993 to 1.099 for concrete bins. Pack factors predicted by the FSA-W method ranged from 0.985 to 1.126 for steel bins and from 1.012 to 1.101 for concrete bins. The average absolute and median differences between the WPACKING-predicted mass and reported mass were 1.64% and -1.26%, respectively, for corrugated steel bins and 3.75% and 2.16%, respectively, for concrete bins. In most cases, WPACKING underpredicted the mass in corrugated steel bins and overpredicted the mass in concrete bins. Comparison of the RMA-predicted mass and reported mass showed an average absolute difference of 4.41% with a median difference of 1.91% for HRW wheat in steel bins and an average absolute difference of 3.25% with a median difference of 1.03% for concrete bins. For the FSA-W-predicted mass versus reported mass, the average absolute and median differences were 3.40% and 3.86%, respectively, for steel bins and 4.34% and 3.50%, respectively, for concrete bins. Most of the mass values were overpredicted by both the RMA and FSA-W methods. Some of the large differences observed for concrete bins can be attributed to the unique geometry of these bins and the difficulty in describing these bin shapes mathematically. Overall, compared to the reported mass, WPACKING predicted the mass of grain in the bins with less error than the current RMA and FSA-W methods. Some of the differences may be because the RMA and FSA-W methods do not include the effects of grain moisture content, bin wall type, and grain height on pack factors

Pack Factor Measurements for Corn in Grain Storage Bins

Shelled yellow corn is commonly stored in concrete or corrugated steel bins. Granular materials compact under their own weight, primarily due to particle rearrangement, leading to an increase in bulk density and a change in volume when stored. Reliable grain pack factors are needed to estimate storage capacities and to accurately monitor grain inventories. A science-based model (WPACKING) of pack factors is available that uses the differential form of Janssen’s equation and takes into account the variation in density caused by pressure variation with height and moisture content of the grain and accounts for the effects of grain type, test weight, bin geometry, and bin material. However, this model needs to be compared to field data over a wide range of conditions to ensure robust prediction accuracy. The objective of this research was to determine the field pack factors and bin capacities for on-farm and commercial bins used to store corn in the U.S. and compare them to predictions of the WPACKING program. Bin inventory measurements were conducted in concrete bins with depths up to 31.4 m (114.8 ft) and corrugated steel bins with diameters up to 32.8 m (156Â ft). These values were also compared to the techniques used by the USDA Risk Management Agency (RMA) and the USDA Farm Service Agency, Warehouse Branch (FSA-W). The differences between predicted and reported mass were -4.54% (maximum underprediction) to +4.53% (maximum overprediction) for WPACKING, -2.69% to 4.97% for the RMA method, and -3.33% to + 5.67% for the FSA-W method. The absolute average difference was lowest for the WPACKING model (0.90%) compared to the RMA and FSA-W methods (1.61% and 1.86%, respectively). WPACKING had less than half as many prediction differences above 1% (13 out of 51 bins) as did the RMA and FSA-W methods, which had 29 out of 51 and 33 out of 51, respectively. The RMA and FSA-W methods do not take into account the variations in pack factor due to bin type and moisture content of the stored grain