Hydrodynamical Simulations of the Barred Spiral Galaxy NGC 1097

NGC 1097 is a nearby barred spiral galaxy believed to be interacting with the elliptical galaxy NGC 1097A located to its northwest. It hosts a Seyfert 1 nucleus surrounded by a circumnuclear starburst ring. Two straight dust lanes connected to the ring extend almost continuously out to the bar. The other ends of the dust lanes attach to two main spiral arms. To provide a physical understanding of its structural and kinematical properties, two-dimensional hydrodynamical simulations have been carried out. Numerical calculations reveal that many features of the gas morphology and kinematics can be reproduced provided that the gas flow is governed by a gravitational potential associated with a slowly rotating strong bar. By including the self-gravity of the gas disk in our calculation, we have found the starburst ring to be gravitationally unstable which is consistent with the observation in \citet{hsieh11}. Our simulations show that the gas inflow rate is 0.17 M_\sun yr$^{-1}$ into the region within the starburst ring even after its formation, leading to the coexistence of both a nuclear ring and a circumnuclear disk.Comment: 32 pages, 14 figures, 1 table, accepted for publication in the Ap

Abundances and Isotope Ratios in the Magellanic Clouds: The Star Forming Environment of N113

With the goal of deriving the physical and chemical conditions of star forming regions in the Large Magellanic Cloud (LMC), a spectral line survey of the prominent star forming region N113 is presented. The observations cover parts of the frequency range from 85 GHz to 357 GHz and include 63 molecular transitions from a total of 16 species, among them spectra of rare isotopologues. Maps of selected molecular lines as well as the 1.2 mm continuum distribution are also presented. Molecular abundances in the core of the complex are found to be consistent with a photon dominated region (PDR) that is nitrogen deficient, with the potential exception of N2H+. Densities range from 5x10^3 cm-3 for CO to almost 10^6 for CS and HCN, indicating that only the densest regions provide sufficient shielding even for some of the most common species. An ortho- to para-H_2CO ratio of ~3 hints at H_2CO formation in a warm (>=40 K) environment. Isotope ratios are 12C/13C ~ 49+-5, 16O/18O ~ 2000+-250, 18O/17O ~ 1.7+-0.2 and 32S/34S ~ 15. Agreement with data from other star forming clouds shows that the gas is well mixed in the LMC . The isotope ratios do not only differ from those seen in the Galaxy. They also do not form a continuation of the trends observed with decreasing metallicity from the inner to the outer Galaxy. This implies that the outer Galaxy, is not providing a transition zone between the inner Galaxy and the metal poor environment of the Magellanic Clouds. A part of this discrepancy is likely caused by differences in the age of the stellar populations in the outer Galaxy and the LMC.Comment: 50 pages, 13 figures, accepted for publication in Ap

Evaluation of hyperspectral technology for assessing the presence and severity of peripheral artery disease

BackgroundHyperspectral imaging is a novel technology that can noninvasively measure oxyhemoglobin and deoxyhemoglobin concentrations to create an anatomic oxygenation map. It has predicted healing of diabetic foot ulcers; however, its ability to assess peripheral arterial disease (PAD) has not been studied. The aims of this study were to determine if hyperspectral imaging could accurately assess the presence or absence of PAD and accurately predict PAD severity.MethodsThis prospective study included consecutive consenting patients presenting to the vascular laboratory at the Jesse Brown VA Medical Center during a 10-week period for a lower extremity arterial study, including ankle-brachial index (ABI) and Doppler waveforms. Patients with lower extremity edema were excluded. Patients underwent hyperspectral imaging at nine angiosomes on each extremity. Additional sites were imaged when tissue loss was present. Medical records of enrolled patients were reviewed for demographic data, active medications, surgical history, and other information pertinent to PAD. Patients were separated into no-PAD and PAD groups. Differences in hyperspectral values between the groups were evaluated using the two-tailed t test. Analysis for differences in values over varying severities of PAD, as defined by triphasic, biphasic, or monophasic Doppler waveforms, was conducted using one-way analysis of variance. Hyperspectral values were correlated with the ABI using a Pearson bivariate linear correlation test.ResultsThe study enrolled 126 patients (252 limbs). After exclusion of 15 patients, 111 patients were left for analysis, including 46 (92 limbs) no-PAD patients and 65 (130 limbs) PAD patients. Groups differed in age, diabetes, coronary artery disease, congestive heart failure, tobacco use, and insulin use. Deoxyhemoglobin values for the plantar metatarsal, arch, and heel angiosomes were significantly different between patients with and without PAD (P < .005). Mean deoxyhemoglobin values for the same three angiosomes showed significant differences between patients with monophasic, biphasic, and triphasic waveforms (P < .05). In patients with PAD, there was also significant correlation between deoxyhemoglobin values and ABI for the same three angiosomes (P = .001). Oxyhemoglobin values did not predict the presence or absence of PAD, did not correlate with PAD severity, and did not correlate with the ABI.ConclusionsThese results suggest the ability of hyperspectral imaging to detect the presence of PAD. Hyperspectral measurements can also evaluate different severities of PAD

Absence of rearrangements in the BRCA2 gene in human cancers

Mutations of BRCA2 in sporadic breast and ovarian carcinomas are exceedingly rare. This led to the suggestion that large genomic rearrangements could be involved. We performed Southern blots in genomic DNA from 130 primary breast cancers and 83 cancer cell lines (breast, ovarian, pancreatic and small cell lung carcinomas) and found no genomic rearrangements. These results suggest that a gene other than BRCA2 is the target of the frequent 13q12.3 allelic deletions in human cancers. © 2001 Cancer Research Campaign http://www.bjcancer.co

Evaluation of Site Response Using Downhole Array Data from a Liquefied Site

Downhole array ground motions recorded at Port Island during the mainshock and aftershocks of the Hyogoken-Nanbu (Kobe) earthquake of January 17, 1995, were used in this study for evaluating the reasonableness of commonly used site response analysis techniques (both nonlinear effective stress and equivalent linear total stress techniques). The nonlinear effective stress analyses were performed using the computer code SUMDES; the equivalent linear total stress analyses were performed using the computer code SHAKE. Dynamic soil properties as well as other data for characterizing nonlinear stress-strain, cyclic strength, and pore pressure generation and dissipation of the Masado till that liquefied during the mainshock of the Kobe earthquake were derived from published papers

Imaging and Characterization of Thick Production-Line Microelectronic Components using Transmission Acoustic Microscopy

The interfacial regions of four types of production-line microelectronic components (die-bonded transistor headers, high power silicon transistors, chip-resistors, and multilayer chip-capacitors) have been examined using a transmission scanning acoustic microscope operating at 150 MHz and a combination of modes. Flaws, voids, and defects in these components have been detected. Some characterization of these defects has also been obtained

Magnetoresistive biosensors with on-chip pulsed excitation and magnetic correlated double sampling.

Giant magnetoresistive (GMR) sensors have been shown to be among the most sensitive biosensors reported. While high-density and scalable sensor arrays are desirable for achieving multiplex detection, scalability remains challenging because of long data acquisition time using conventional readout methods. In this paper, we present a scalable magnetoresistive biosensor array with an on-chip magnetic field generator and a high-speed data acquisition method. The on-chip field generators enable magnetic correlated double sampling (MCDS) and global chopper stabilization to suppress 1/f noise and offset. A measurement with the proposed system takes only 20 ms, approximately 50× faster than conventional frequency domain analysis. A corresponding time domain temperature correction technique is also presented and shown to be able to remove temperature dependence from the measured signal without extra measurements or reference sensors. Measurements demonstrate detection of magnetic nanoparticles (MNPs) at a signal level as low as 6.92 ppm. The small form factor enables the proposed platform to be portable as well as having high sensitivity and rapid readout, desirable features for next generation diagnostic systems, especially in point-of-care (POC) settings

Dynamic Soil-Foundation-Structure Interaction Analyses of Large Caissons

Large cellular reinforced concrete caissons exist as foundations of major long-span bridges across waterways in many parts of the country. This study was conducted to evaluate the important factors affecting the seismic response of large caissons. The paper presents the results of equivalent linear and non-linear analyses performed for a typical caisson idealized based on the cellular caisson at Pier W3 of the West San Francisco Bay Bridge subject to ground motion with a peak rock acceleration of 0.6 g. This caisson is 38.7 m (127 fi) long by 22.9 m (75 ft) wide submerged in about 32.6 m (107 ft) of water. It is embedded in 33.5 m (110 fi) of soil deposits and is founded on rock. Equivalent linear 3-D and 2-D analyses conducted in the direction of the short axis (longitudinal) were performed using a modified version of computer program SASSI. The results of these 3-D and 2-D analyses are similar. Non-linear analyses were performed for 2-D models using computer program FLAC. The results indicate that side gapping, base lifting, interface sliding, and soil yielding reduce the earth pressure, base bearing stress, caisson shear and bending moment, and caisson motions. However, the frequency characteristics of the responses appear to be relatively unaffected

Quantum Perfect-Fluid Kaluza-Klein Cosmology

The perfect fluid cosmology in the 1+d+D dimensional Kaluza-Klein spacetimes for an arbitrary barotropic equation of state $p= n \rho$ is quantized by using the Schutz's variational formalism. We make efforts in the mathematics to solve the problems in two cases. For the first case of the stiff fluid $n=1$ we exactly solve the Wheeler-DeWitt equation when the $d$ space is flat. After the superposition of the solutions we analyze the Bohmian trajectories of the final-stage wave-packet functions and show that the flat $d$ spaces and the compact $D$ spaces will eventually evolve into finite scale functions. For the second case of $n \approx 1$, we use the approximated wavefunction in the Wheeler-DeWitt equation to find the analytic forms of the final-stage wave-packet functions. After analyzing the Bohmian trajectories we show that the flat $d$ spaces will be expanding forever while the scale function of the contracting $D$ spaces would not become zero within finite time. Our investigations indicate that the quantum effect in the quantum perfect-fluid cosmology could prevent the extra compact $D$ spaces in the Kaluza-Klein theory from collapsing into a singularity or that the "crack-of-doom" singularity of the extra compact dimensions is made to occur at $t=\infty$.Comment: Latex 18 pages, add section 2 to introduce the quantization of perfect flui

The 6-vertex model of hydrogen-bonded crystals with bond defects

It is shown that the percolation model of hydrogen-bonded crystals, which is a 6-vertex model with bond defects, is completely equivalent with an 8-vertex model in an external electric field. Using this equivalence we solve exactly a particular 6-vertex model with bond defects. The general solution for the Bethe-like lattice is also analyzed.Comment: 13 pages, 6 figures; added references for section