Using a laser aureole to invert lidar return

An aureole generated by a laser beam was studied. The strength of the signal redirected towards a sensor high above the surface by a combination of one scattering event in the marine boundary layer (mbl) and one single reflection event from the ocean surface was estimated. A model of mbl aerosol size distributions was used to estimate Mie scattering for a wide range of meteorolocial conditions. The sea surface reflection was determined from a Gaussian model of the wave slopes. These laser aureoles which were estimated over the wide range of conditions and were normalized by the reflected laser light were found to be highly correlated with the optical depth of the boundary layer. By estimating optical depth from the aureole, the Bernoulli-Riccati inversion of lidar return could be constrained and the inversion accuracy improved. A Monte Carlo program was developed to study the laser aureole generated by up to 8 orders of reflection and scattering. The aureole was generated by a narrow, 10 nsec laser pulse at 1.06 microns and measured by a receiver 10 km above the ocean surface. The original theoretical computation compared well with the Monte Carlo method. When multiple scattereffects were included, the normalized aureole was still highly correlated with the mbl optical depth over the range of conditions

ECTOPIC OSSIFICATION FOLLOWING TOTAL HIP ARTHROPLASTY: IS DIFFUSE IDIOPATHIC SKELETAL HYPEROSTOSIS A RISK FACTOR?

Total hip a≪hroplasty may be followed by ectopic bone formation. An increased frequency has been suspected in patients with diffuse idiopathic skeletal hypcrostosis (DISH). In 204 patients we found that, of the 38 subjects with pre-existing DISH, 29% developed postoperative ossification compared with only 10% in those without DISH (p ≪; 0.01). DISH is therefore a risk factor for postoperative ectopic bone formation. In a separate study of 1325 patients (not analysed for spinal DISH), we looked for correlations between the severity of postoperative ectopic bone and clinical measurements. Even for the more severe ossification grades (n = 112), only 10% reported serious pain and only 26% had reduced hip flexion (≪70°). Thus, periprosthetic ectopic bone is not sufficiently important to justify the routine use of preventative drugs such as bisphosphonates in patients with DISH undergoing total hip replacemen

Microscopic Model versus Systematic Low-Energy Effective Field Theory for a Doped Quantum Ferromagnet

We consider a microscopic model for a doped quantum ferromagnet as a test case for the systematic low-energy effective field theory for magnons and holes, which is constructed in complete analogy to the case of quantum antiferromagnets. In contrast to antiferromagnets, for which the effective field theory approach can be tested only numerically, in the ferromagnetic case both the microscopic and the effective theory can be solved analytically. In this way the low-energy parameters of the effective theory are determined exactly by matching to the underlying microscopic model. The low-energy behavior at half-filling as well as in the single- and two-hole sectors is described exactly by the systematic low-energy effective field theory. In particular, for weakly bound two-hole states the effective field theory even works beyond perturbation theory. This lends strong support to the quantitative success of the systematic low-energy effective field theory method not only in the ferromagnetic but also in the physically most interesting antiferromagnetic case.Comment: 34 pages, 1 figur

Progressive Star Bursts and High Velocities in the Infrared Luminous, Colliding Galaxy Arp 118

In this paper we demonstrate for the first time the connection between the spatial and temporal progression of star formation and the changing locations of the very dense regions in the gas of a massive disk galaxy (NGC 1144) in the aftermath of its collision with a massive elliptical (NGC 1143). These two galaxies form the combined object Arp 118, a collisional ring galaxy system. The results of 3D, time-dependent, numerical simulations of the behavior of the gas, stars, and dark matter of a disk galaxy and the stars and dark matter in an elliptical during a collision are compared with multiwavelength observations of Arp 118. The collision that took place approximately 22 Myr ago generated a strong, non-linear density wave in the stars and gas in the disk of NGC 1144, causing the gas to became clumped on a large scale. This wave produced a series of superstarclusters along arcs and rings that emanate from the central point of impact in the disk. The locations of these star forming regions match those of the regions of increased gas density predicted the time sequence of models. The models also predict the large velocity gradients observed across the disk of NGC 1144. These are due to the rapid radial outflow of gas coupled to large azimuthal velocities in the expanding ring, caused by the impact of the massive intruder.Comment: 12 pages in document, and 8 figures (figures are separate from the document's file); Submitted to Astrophysical Journal Letter

Policy options in addressing livestock's contribution to climate change

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Bupivacaine crystal deposits after long-term epidural infusion

The case of a 45-year-old male patient (body weight 52kg, height 1.61m) with a locally invasive gastric carcinoma infiltrating into the retroperitoneal space is reported. Because of severe cancer pain a tunnelled thoracic epidural catheter (EC) was placed at thoracic spinal level 7/8 and a local anesthetic (LA) mixture of bupivacaine 0.25 % and morphine 0.005 % was infused continuously at 6mlh−1. To optimize pain therapy the concentration was doubled (bupivacaine 0.5 %, morphine 0.01 %) 3 months later but the infusion rate was reduced to 3mlh−1 thus the total daily dose did not change. The patient died 6 months after initiation of the epidural analgesia from the underlying disease. The total amount of bupivacaine infused was 69g and of morphine 1.37g. The patient never reported any neurological complications. The autopsy revealed large white crystalline deposits in the thoracic epidural space which were identified as bupivacaine base by infrared spectrometry. Morphine could not be detected. A histological examination showed unreactive fatty tissue necrosis within the crystalline deposits but nerve tissue could not be identified. It is concluded that the bupivacaine crystalline deposits arose due to precipitation but the clinical significance with regard to sensory level and neuraxial tissue toxicity is unknow

Dominant g(9/2)^2 neutron configuration in the 4+1 state of 68Zn based on new g factor measurements

The $g$ factor of the $4_1^+$ state in $^{68}$Zn has been remeasured with improved energy resolution of the detectors used. The value obtained is consistent with the previous result of a negative $g$ factor thus confirming the dominant $0g_{9/2}$ neutron nature of the $4_1^+$ state. In addition, the accuracy of the $g$ factors of the $2_1^+$, $2_2^+$ and $3_1^-$ states has been improved an d their lifetimes were well reproduced. New large-scale shell model calculations based on a $^{56}$Ni core and an $0f_{5/2}1pg_{9/2}$ model space yield a theoretical value, $g(4_1^+) = +0.008$. Although the calculated value is small, it cannot fully explain the experimental value, $g(4_1^+) = -0.37(17)$. The magnitude of the deduced B(E2) of the $4_1^+$ and $2_1^+$ transition is, however, rather well described. These results demonstrate again the importance of $g$ factor measurements for nuclear structure determination s due to their specific sensitivity to detailed proton and neutron components in the nuclear wave functions.Comment: 7 pages, 3 figs, submitted to PL

On the Deconfinement Phase Transition in the Resonance Gas

We obtain the constraints on the ruling parameters of the dense hadronic gas model at the critical temperature and propose the quasiuniversal ratios of the thermodynamic quantities. The possible appearence of thermodynamical instability in such a model is discussed.Comment: 7 pages, plain LaTeX, BI-TP 94/4

Anisotropic thermal expansion and magnetostriction of YNi2_2B2_2C single crystals

We present results of anisotropic thermal expansion and low temperature magnetostriction measurements on YNi$_2$B$_2$C single crystals grown by high temperature flux and floating zone techniques. Quantum oscillations of magnetostriction were observed at low temperatures for $H \| c$ starting at fields significantly below $H_{c2}$ ($H < 0.7 H_{c2}$). Large irreversible, longitudinal magnetostriction was seen in both, in-plane and along the c-axis, directions of the applied magnetic field in the intermediate superconducting state. Anisotropic uniaxial pressure dependencies of $T_c$ were evaluated using results of zero field, thermal expansion measurements