Electrical anisotropy due to gas hydrate-filled fractures

In 2006, the Indian National Gas Hydrate Program Expedition 01, or NGHP-01, discovered gas hydrate as fill in near-vertical fractures in unconsolidated sediments at several drilling sites on the Indian continental margins. These gas hydrate-filled fractures were identified on logging-while-drilling resistivity images. The gas hydrate-filled fracture intervals coincide with high measured resistivity at the NGHP-01 sites. High measured resistivity translates into high hydrate saturations via Archie's equation; however, these high saturations contradict lower gas hydrate saturations determined from pressure core and chlorinity measurements. Also, in intervals with near-vertical gas hydrate-filled fractures, there is considerable separation between phase shift and attenuation resistivity logs, with 2-MHz resistivity measurements being significantly higher than 400-kHz resistivity measurements. We modeled the sensitivity of the propagation resistivity measurements in the gas hydrate-filled fracture intervals at NGHP-01 Sites 5 and 10. Near-vertical hydrate-filled fractures can cause the abnormally high resistivity measurements in vertical holes due to electrical anisotropy. The model suggests the gas hydrate saturations in situ are usually significantly lower than those calculated from Archie's equation. In addition, these modeled gas hydrate saturations generally agree with the lower gas hydrate saturations obtained from pressure core and chlorinity measurements at NGHP-01 Sites 5 and 10

Recainam, A potent new antiarrhythmic agent: Effects on complex ventricular arrhythmias

The antiarrhythmic efficacy and safety of intravenous recainam, a newly synthesized compound displaying potent class I antiarrhythmic activity, were tested in 10 hospitalized patients with frequent (>30/h) complex ventricular ectopic beats. There were seven men and three women of average age 57 years (range 21 to 74); five had ischemic heart disease, three had cardiomyopathy and two had valvular heart disease. Recainam was given as a 3.0 mg/kg per 40 min loading infusion followed by a 0.9 mg/kg per h maintenance infusion over a 24 hour observation period. Arrhythmia response was assessed both in the short term (comparing 2 hours before and 1 hour after drug loading) and in the long term (comparing 48 hours before drug loading and 23 hours of maintenance infusion).The median frequency of total premature ventricular complexes decreased in the short term by 99.6% (from 392.5 to 1.5/h, p < 0.005) and in the long term by 99.7% (from 435 to 1.3/h, p < 0.01). Repetitive beats were suppressed by a median of 100% both in the short term (p < 0.006) and during 24 hour infusion (from 80.9 to 0/h, p < 0.003). More than 90% suppression of repetitive beats occurred in all 10 patients (100%) and more than 90% suppression of total arrhythmias occurred in 9 patients (90%) during the maintenance period. Electrocardiographic PR and QRS intervals increased by 19% (p < 0.001) and 24% (p < 0.003), respectively, during therapy, but the JTc interval decreased (p < 0.001). Plasma recainam concentrations averaged 5.2 ± 0.9 μg/ml after loading and 3.0 ± 0.5 μg/ml during maintenance therapy. No adverse symptoms occurred.In summary, recainam is a promising, highly efficacious and well tolerated agent when administered intravenously for short-term and maintenance suppression of complex ventricular arrhythmias. The efficacy of oral and intravenous recainam for arrhythmia management deserves further evaluation

Electrical anisotropy of gas hydrate-bearing sand reservoirs in the Gulf of Mexico

We present new results and interpretations of the electrical anisotropy and reservoir architecture in gas hydrate-bearing sands using logging data collected during the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II. We focus specifically on sand reservoirs in Hole Alaminos Canyon 21 A (AC21-A), Hole Green Canyon 955 H (GC955-H) and Hole Walker Ridge 313 H (WR313-H). Using a new logging-while-drilling directional resistivity tool and a one-dimensional inversion developed by Schlumberger, we resolve the resistivity of the current flowing parallel to the bedding, R‖ and the resistivity of the current flowing perpendicular to the bedding, R⊥. We find the sand reservoir in Hole AC21-A to be relatively isotropic, with R‖ and R⊥ values close to 2 Ω m. In contrast, the gas hydrate-bearing sand reservoirs in Holes GC955-H and WR313-H are highly anisotropic. In these reservoirs, R‖ is between 2 and 30 Ω m, and R⊥ is generally an order of magnitude higher. Using Schlumberger’s WebMI models, we were able to replicate multiple resistivity measurements and determine the formation resistivity the gas hydrate-bearing sand reservoir in Hole WR313-H. The results showed that gas hydrate saturations within a single reservoir unit are highly variable. For example, the sand units in Hole WR313-H contain thin layers (on the order of 10–100 cm) with varying gas hydrate saturations between 15 and 95%. Our combined modeling results clearly indicate that the gas hydrate-bearing sand reservoirs in Holes GC955-H and WR313-H are highly anisotropic due to varying saturations of gas hydrate forming in thin layers within larger sand units

Diabetes and Motor Vehicle Crashes: A Systematic Evidence-Based Review and Meta-Analysis

The primary objective of this systematic review was to address the question, “Are drivers with diabetes mellitus at greater risk for a motor vehicle crash than comparable drivers without the disease?” and secondarily, to address the question, “Are insulin-treated diabetics at higher risk for crash?” Our searches identified 16 articles that addressed these questions. An assessment of study quality of the included studies found them to be in the low-to-moderate range. While attempts were made to control for differences in the characteristics of individuals that may confound the relationship between diabetes and crash risk in all included studies, most failed to control for exposure. A random-effects metaanalysis found that individuals with diabetes have a 19% increased risk for a motor vehicle crash when compared to similar individuals without diabetes. We found no compelling evidence to suggest that insulin-treated individuals are at higher risk for motor vehicle crash than individuals with diabetes not being treated with insulin. We discuss the implications of these findings

Issues in Research on the Young Chronically III Child

A major goal of research on chronic illness in children is to determine how the illness interacts with developmental processes. The child must be studied within the context of the family, the school, and the health care system. Problems in research include the use of appropriate control groups and matching on control variables. The generic, or cross-categorical, approach has led to the identification of factors affecting children regardless of particular illness. Adjustment to school depends on coordination of the family and health professionals with personnel within the school.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68724/2/10.1177_027112148600500406.pd

Information logistics and fog computing: The DITAS∗ approach

Data-intensive applications are usually developed based on Cloud resources whose service delivery model helps towards building reliable and scalable solutions. However, especially in the context of Internet of Things-based applications, Cloud Computing comes with some limitations as data, generated at the edge of the network, are processed at the core of the network producing security, privacy, and latency issues. On the other side, Fog Computing is emerging as an extension of Cloud Computing, where resources located at the edge of the network are used in combination with cloud services. The goal of this paper is to present the approach adopted in the recently started DITAS project: the design of a Cloud platform is proposed to optimize the development of data-intensive applications providing information logistics tools that are able to deliver information and computation resources at the right time, right place, with the right quality. Applications that will be developed with DITAS tools live in a Fog Computing environment, where data move from the cloud to the edge and vice versa to provide secure, reliable, and scalable solutions with excellent performance

'Hole-digging' in ensembles of tunneling Molecular Magnets

The nuclear spin-mediated quantum relaxation of ensembles of tunneling magnetic molecules causes a 'hole' to appear in the distribution of internal fields in the system. The form of this hole, and its time evolution, are studied using Monte Carlo simulations. It is shown that the line-shape of the tunneling hole in a weakly polarised sample must have a Lorentzian lineshape- the short-time half-width $\xi_o$ in all experiments done so far should be $\sim E_0$, the half-width of the nuclear spin multiplet. After a time $\tau_o$, the single molecule tunneling relaxation time, the hole width begins to increase rapidly. In initially polarised samples the disintegration of resonant tunneling surfaces is found to be very fast.Comment: 4 pages, 5 figure

Mixed ice accretion on aircraft wings

Ice accretion is a problematic natural phenomenon that an effects a wide range of engineering applications including power cables, radio masts and wind turbines. Accretion on aircraft wings occurs when supercooled water droplets freeze instantaneously on impact to form rime ice or runback as water along the wing to form glaze ice. Most models to date have ignored the accretion of mixed ice, which is a combination of rime and glaze. A parameter we term the `freezing fraction', is defined as the fraction of a supercooled droplet that freezes on impact with the top surface of the accretion ice to explore the concept of mixed ice accretion. Additionally we consider different `packing densities' of rime ice, mimicking the different bulk rime densities observed in nature. Ice accretion is considered in four stages: rime, primary mixed, secondary mixed and glaze ice. Predictions match with existing models and experimental data in the limiting rime and glaze cases. The mixed ice formulation consequently however provides additional insight into the composition of the overall ice structure, which ultimately influences adhesion and ice thickness; and shows that for similar atmospheric parameter ranges, this simple mixed ice description leads to very different accretion rates. A simple one-dimensional energy balance was solved to show how this freezing fraction parameter increases with decrease in atmospheric temperature, with lower freezing fraction promoting glaze ice accretion

Quantum Relaxation of Magnetisation in Magnetic Particles

At temperatures below the magnetic anisotropy energy, monodomain magnetic systems (small particles, nanomagnetic devices, etc.) must relax quantum mechanically. This quantum relaxation must be mediated by the coupling to both nuclear spins and phonons (and electrons if either particle or substrate is conducting. We analyze the effect of each of these couplings, and then combine them. Conducting systems can be modelled by a "giant Kondo" Hamiltonian, with nuclear spins added in as well. At low temperatures, even microscopic particles on a conducting substrate (containing only $10-50$ spins) will have their magnetisation frozen over millenia by a combination of electronic dissipation and the "degeneracy blocking" caused by nuclear spins. Raising the temperature leads to a sudden unblocking of the spin dynamics at a well defined temperature. Insulating systems are quite different. The relaxation is strongly enhanced by the coupling to nuclear spins. At short times the magnetisation of an ensemble of particles relaxes logarithmically in time, after an initial very fast decay; this relaxation proceeds entirely via the nuclear spins. At longer times phonons take over, but the decay rate is still governed by the temperature-dependent nuclear bias field acting on the particles - decay may be exponential or power-law depending on the temperature. The most surprising feature of the results is the pivotal role played by the nuclear spins. The results are relevant to any experiments on magnetic particles in which interparticle dipolar interactions are unimportant. They are also relevant to future magnetic device technology.Comment: 30 pages, RevTex, e:mail , Submitted to J.Low Temp.Phys. on 1 Nov. 199

Protein interactions in Xenopus germ plasm RNP particles

Hermes is an RNA-binding protein that we have previously reported to be found in the ribonucleoprotein (RNP) particles of Xenopus germ plasm, where it is associated with various RNAs, including that encoding the germ line determinant Nanos1. To further define the composition of these RNPs, we performed a screen for Hermes-binding partners using the yeast two-hybrid system. We have identified and validated four proteins that interact with Hermes in germ plasm: two isoforms of Xvelo1 (a homologue of zebrafish Bucky ball) and Rbm24b and Rbm42b, both RNA-binding proteins containing the RRM motif. GFP-Xvelo fusion proteins and their endogenous counterparts, identified with antisera, were found to localize with Hermes in the germ plasm particles of large oocytes and eggs. Only the larger Xvelo isoform was naturally found in the Balbiani body of previtellogenic oocytes. Bimolecular fluorescence complementation (BiFC) experiments confirmed that Hermes and the Xvelo variants interact in germ plasm, as do Rbm24b and 42b. Depletion of the shorter Xvelo variant with antisense oligonucleotides caused a decrease in the size of germ plasm aggregates and loosening of associated mitochondria from these structures. This suggests that the short Xvelo variant, or less likely its RNA, has a role in organizing and maintaining the integrity of germ plasm in Xenopus oocytes. While GFP fusion proteins for Rbm24b and 42b did not localize into germ plasm as specifically as Hermes or Xvelo, BiFC analysis indicated that both interact with Hermes in germ plasm RNPs. They are very stable in the face of RNA depletion, but additive effects of combinations of antisense oligos suggest they may have a role in germ plasm structure and may influence the ability of Hermes protein to effectively enter RNP particles