bluuebunny/crossref_metadata_2025 huggingface dataset:
A population of high-redshift type 2 quasars – II. Radio properties
Authors: Martínez-Sansigre Alejo , Rawlings Steve , Garn Timothy , Green David A. , Alexander Paul , Klöckner Hans-Rainer , Riley Julia M.
Published: October 2006

We present multi-frequency radio observations of a sample of z∼ 2 obscured (type 2) quasars in the Spitzer extragalactic First Look Survey area. We combine the public data at 1.4 GHz, used in the selection of these sources, with new observations at 610 MHz (Giant Meterwave Radio Telescope) and at 4.9 GHz (Very Large Array). We find that the sample includes sources with steep, flat and gigahertz-peaked spectra. There are no strong correlations between the presence or absence of emission lines in the optical spectra and the radio spectral properties of the sample. However, there are no secure flat-spectrum type 2 quasars with narrow emission lines which would be problematic for unified schemes. Most of the population have straight radio spectra with spectral index α∼ 1 as is expected for developed, potentially Fanaroff–Riley type I-like jets in which continuous injection of relativistic electrons is accompanied by inverse Compton losses against the cosmic microwave background.
Blowing the whistle on healthcare fraud: Should I?
Authors: Hannigan Norma Stephens
Published: October 2006

Purpose:The purpose of this article is to explore some of the factors involved when a nurse practitioner (NP) is confronted with a healthcare fraud situation. Ethical concepts and decision‐making strategies are provided, as well as practical legal considerations.

Data sources:Government Internet Web sites; healthcare management, ethics, and nursing journals.

Conclusions:There are many forms of healthcare fraud. Healthcare fraud saps financial resources from the healthcare system and from individuals. The decision to blow the whistle on a colleague or organization is not an easy one and has potential for great discomfort. There are ethical decision‐making strategies and practical considerations for the process of whistle‐blowing should it become necessary.

Implications for practice:NPs may be confronted daily with billing and reimbursement issues. Being prepared to recognize healthcare fraud and knowing the ramifications of whistle‐blowing are important tools to have in one’s practice repertoire.
The salt water intrusion problem and water conservation practices in southeast Georgia, USA
Authors: Gibbison Godfrey A. , Randall James
Published: October 2006

This paper presents the results of investigations into the attitudes to the environmental risk posed by salt water intrusion into underground aquifers in the south‐eastern United States. Also investigated is whether individuals have adopted water conservation practices in light of the salt water intrusion threat. Both bivariate analysis and results from logistic regression are presented. It is shown that while a majority of respondents agree that salt water intrusion is a serious threat to the region's water supply, only a small proportion of residents practise conservation on a regular basis. It is suggested that state and local government provide incentives for residents to change their water‐use technology, which might be more effective than price mechanisms.
Desire
Authors: Schroeder Tim
Published: October 2006

Desires move us to action, give us urges, incline us to joy at their satisfaction, and incline us to sorrow at their frustration. Naturalistic work on desire has focused on distinguishing which of these phenomena are part of the nature of desire, and which are merely normal consequences of desiring. Three main answers have been proposed. The first holds that the central necessary fact about desires is that they lead to action. The second makes pleasure the essence of desire. And the third holds that the central necessary fact about desires is that they open us to reward‐based learning.
Consequences of coronary artery stenting for non‐cardiac surgery
Authors: BUSLEY RAIMUND , DIETRICH WULF
Published: October 2006

Percutaneous coronary intervention with intracoronary stenting is a routine procedure in the treatment of coronary artery disease today. While complication rates of in‐stent stenosis and thromboembolic complications dropped over the years due to improved stent design, material, coating and consequent antiplatelet medication, major concerns remain relating to non‐cardiac surgery following briefly after coronary artery stent implantation. A mortality rate of almost 5% has to be expected in a mixed surgical and orthopedic population after coronary artery stenting. Data about cardiac surgery briefly after stent implantation are not available. The risk of major bleeding following continued perioperative antiplatelet therapy has to be balanced against the risk of stent thrombosis by discontinuation of antiplatelet medication in these patients. The careless withdrawal of antiplatelet therapy preoperatively must be avoided.
Ecosystem consequences of the regional species pool
Authors: Naeslund Björn , Norberg Jon
Published: October 2006

In this study we analyse with an experiment how the spatial area from which the species pool is sampled, i.e. local vs regional, can have functional consequences for ecosystem processes and structure. Particularly, we analysed how major stocks and processes respond to a change in basal productivity and how this depends on the source of the species pool. The experimental microcosms used in this experiment were developed by inoculating nutrient solution with samples of rockpool sediment containing resting stages. Here we show that communities developed from sediment samples of single origin (local communities) exhibit important differences in ecosystem structure and their response to a productivity gradient compared to systems developed from mixed samples of multiple and spatially dispersed origin (regional communities). The difference between local and regional communities was most pronounced for zooplankton which had much lower abundances in the local communities compared to the regional communities resulting in cascading effects on phytoplankton. We demonstrate that the spatial extend from which the species pool is sampled can affect ecosystem structure and functioning comparable in magnitude to changes in the basal productivity of the system. We discuss with a conceptual model how the regional species pool is important for sustaining diversity in functional groups, and how higher trophic levels are more sensitive to changes in the regional species pool.
Coupled Stress and Pressure Waves Propagation in an Elastic Solid Tube Submerged in Fluids
Authors: Seibi A. C. , Pervez T. , Karrech A. , Al-Hiddabi S.
Published: October 2006

The present paper studies the effect of mandrel pop out on the dynamics of a solid tubular submerged in fluids of a typical vertical wellbore. A mathematical model describing the stress and pressure waves within the tubular-fluid system (inner and outer fluids as well as solid tube) has been developed. The model takes into account the coupling effect of the three mediums. A specific case of a 127mm solid tubular, placed inside a 340mm borehole with different inner and outer fluids was considered. An analytical solution of the developed model was obtained. It was found that the excitation of the system splits into several components and propagates within the three mediums. In addition, the coupling effect revealed modification in the normal waves’ speeds and frequencies as compared to the uncoupled solution and identifies associated natural frequencies. Moreover, it was noticed that the maximum vibration occurs at the free end of the tubular and that the tube may experience local buckling in the neighborhood of the fixed end.
Trajectory and Characteristics of Buoyancy and Momentum Dominated Horizontal Jet Flames From Circular and Elliptic Burners
Authors: Smith Tracy , Periasamy Chendhil , Baird Benjamin , Gollahalli S. R.
Published: October 2006

Relative effects of buoyancy and momentum on the characteristics of horizontally oriented circular (Circ) and elliptic (E) burner flames in a quiescent environment over a wide range of jet exit velocities are presented. The major axis of the elliptic burner was oriented horizontally and vertically (referred to as Emaj and Emin flames, respectively). Propane was used as fuel and a small amount of hydrogen was piloted to attach flames to the burner. Global flame characteristics such as flame dimensions, centerline trajectory, emission indices (EI) and radiative fraction, and in-flame transverse concentration and temperature profiles were measured. At a jet exit Reynolds number (Rej) of 2000, based on the area-equivalent diameter of the burner, the flame characteristics were affected by the burner geometry and its orientation. Also, the vertical dimension of the burner exit dictated buoyancy effects. At Rej=12,500, the influence of burner geometry or its orientation was negligible. Elliptic burner flames exhibited lower liftoff and blowout velocities than circular burner flames. Furthermore, the flame stability and nitric oxide emissions were not much affected by the orientation of elliptic burner. Although the elliptic burners produced higher EINO at lower jet exit velocities, the variation in EINO among three burners (Circ, Emaj, and Emin) was insignificant at higher velocities. Some effects of buoyancy on EICO were observed at lower jet exit velocities and the EICO was the lowest for the burners with largest buoyancy flux. Elliptic burner flames produced greater peak flame temperature than the corresponding circular burner flames under most conditions.
Brownian Motion of an Ellipsoid
Authors: Han Y. , Alsayed A. M. , Nobili M. , Zhang J. , Lubensky T. C. , Yodh A. G.
Published: October 2006

We studied the Brownian motion of isolated ellipsoidal particles in water confined to two dimensions and elucidated the effects of coupling between rotational and translational motion. By using digital video microscopy, we quantified the crossover from short-time anisotropic to long-time isotropic diffusion and directly measured probability distributions functions for displacements. We confirmed and interpreted our measurements by using Langevin theory and numerical simulations. Our theory and observations provide insights into fundamental diffusive processes, which are potentially useful for understanding transport in membranes and for understanding the motions of anisotropic macromolecules.
Bacterial Taxa That Limit Sulfur Flux from the Ocean
Authors: Howard Erinn C. , Henriksen James R. , Buchan Alison , Reisch Chris R. , Bürgmann Helmut , Welsh Rory , Ye Wenying , González José M. , Mace Kimberly , Joye Samantha B. , Kiene Ronald P. , Whitman William B. , Moran Mary Ann
Published: October 2006

Flux of dimethylsulfide (DMS) from ocean surface waters is the predominant natural source of sulfur to the atmosphere and influences climate by aerosol formation. Marine bacterioplankton regulate sulfur flux by converting the precursor dimethylsulfoniopropionate (DMSP) either to DMS or to sulfur compounds that are not climatically active. Through the discovery of a glycine cleavage T-family protein with DMSP methyltransferase activity, marine bacterioplankton in the Roseobacter and SAR11 taxa were identified as primary mediators of DMSP demethylation to methylmercaptopropionate. One-third of surface ocean bacteria harbor a DMSP demethylase homolog and thereby route a substantial fraction of global marine primary production away from DMS formation and into the marine microbial food web.
Interface Mobility from Interface Random Walk
Authors: Trautt Zachary T. , Upmanyu Moneesh , Karma Alain
Published: October 2006

Computational studies aimed at extracting interface mobilities require driving forces orders of magnitude higher than those occurring experimentally. We present a computational methodology that extracts the absolute interface mobility in the zero driving force limit by monitoring the one-dimensional random walk of the mean interface position along the interface normal. The method exploits a fluctuation-dissipation relation similar to the Stokes-Einstein relation, which relates the diffusion coefficient of this Brownian-like random walk to the interface mobility. Atomic-scale simulations of grain boundaries in model crystalline systems validate the theoretical predictions and highlight the profound effect of impurities. The generality of this technique, combined with its inherent spatiotemporal efficiency, should allow computational studies to effectively complement experiments in understanding interface kinetics in diverse material systems.
BK
Ca
-Cav Channel Complexes Mediate Rapid and Localized Ca
2+
-Activated K
+
Signaling
Authors: Berkefeld Henrike , Sailer Claudia A. , Bildl Wolfgang , Rohde Volker , Thumfart Jörg-Oliver , Eble Silke , Klugbauer Norbert , Reisinger Ellen , Bischofberger Josef , Oliver Dominik , Knaus Hans-Günther , Schulte Uwe , Fakler Bernd
Published: October 2006

Large-conductance calcium- and voltage-activated potassium channels (BK
Ca
) are dually activated by membrane depolarization and elevation of cytosolic calcium ions (Ca
2+
). Under normal cellular conditions, BK
Ca
channel activation requires Ca
2+
concentrations that typically occur in close proximity to Ca
2+
sources. We show that BK
Ca
channels affinity-purified from rat brain are assembled into macromolecular complexes with the voltage-gated calcium channels Cav1.2 (L-type), Cav2.1 (P/Q-type), and Cav2.2 (N-type). Heterologously expressed BK
Ca
-Cav complexes reconstitute a functional “Ca
2+
nanodomain” where Ca
2+
influx through the Cav channel activates BK
Ca
in the physiological voltage range with submillisecond kinetics. Complex formation with distinct Cav channels enables BK
Ca
-mediated membrane hyperpolarization that controls neuronal firing pattern and release of hormones and transmitters in the central nervous system.
Teach the Controversy!
Authors: Pierce Aaron
Published: October 2006

The Trouble with Physics
. The Rise of String Theory, the Fall of a Science, and What Comes Next.
By Lee Smolin
. Houghton Mifflin, Boston, 2006. 416 pp. $26, C$34.95. ISBN 0-618-55105-0.

Writing for a broad, nonspecialist audience, the author marshals his arguments against string theory and sketches the approach that he believes will replace it.
A Fossil Bee from Early Cretaceous Burmese Amber
Authors: Poinar G. O. , Danforth B. N.
Published: October 2006

The bee fossil record is fragmentary, making it difficult to accurately estimate the antiquity of bee-mediated pollination. Here, we describe a bee fossil [Melittosphex burmensis (new species), Melittosphecidae (new family)] from Early Cretaceous Burmese amber (~100 million years before the present). The fossil provides insights into the morphology of the earliest bees and provides a new minimum date for the antiquity of bees and bee-mediated pollination.
Functional CpG Methylation System in a Social Insect
Authors: Wang Ying , Jorda Mireia , Jones Peter L. , Maleszka Ryszard , Ling Xu , Robertson Hugh M. , Mizzen Craig A. , Peinado Miguel A. , Robinson Gene E.
Published: October 2006

DNA methylation systems are well characterized in vertebrates, but methylation in
Drosophila melanogaster
and other invertebrates remains controversial. Using the recently sequenced honey bee genome, we present a bioinformatic, molecular, and biochemical characterization of a functional DNA methylation system in an insect. We report on catalytically active orthologs of the vertebrate DNA methyltransferases Dnmt1 and Dnmt3a and b, two isoforms that contain a methyl-DNA binding domain, genomic 5-methyl-deoxycytosine, and CpG-methylated genes. The honey bee provides an opportunity to study the roles of methylation in social contexts.
Chronology of Hawaiian Glaciations
Authors: Porter Stephen C. , Stuiver Minze , Yang I. C.
Published: October 2006

Both potassium/argon and carbon-14 ages of lava flows and tephra layers interstratified with glacial deposits on Mauna Kea, Hawaii, indicate that four episodes of ice cap glaciation culminated about 20,000, 55,000, 135,000, and 250,000 years ago. These episodes are correlated with marine isotope stages 2, 4, 6, and 8, marking times of high global ice volume.
Perovskite Oxides: Materials Science in Catalysis
Authors: Voorhoeve R. J. H. , Johnson D. W. , Remeika J. P. , Gallagher P. K.
Published: October 2006

In a time of growing need for catalysts, perovskites have been rediscovered as a family of catalysts of such great diversity that a broad spectrum of scientific disciplines have been brought to bear in their study and application. Because of the wide range of ions and valences which this simple structure can accommodate, the perovskites lend themselves to chemical tailoring. It is relatively simple to synthesize perovskites because of the flexibility of the structure to diverse chemistry. Many of the techniques of ceramic powder preparation are applicable to perovskite catalysts. In their own right, they are therefore of interest as a model system for the correlation of solid-state parameters and catalytic mechanisms. Such correlations have recently been found between the rate and selectivity of oxidation-reduction reactions and the thermodynamic and electronic parameters of the solid.

For commercial processes such as those mentioned in the introduction, perovskite catalysts have not yet proven to be practical. Much of the initial interest in these catalysts related to their use in automobile exhaust control. Current interest in this field centers on noble metal-substituted perovskites resistant to S poisoning for single-bed, dual-bed, and three-way catalyst configurations. The formulations commercially tested to date have shown considerable promise, but long-term stability has not yet been achieved.

A very large fraction of the elements that make up presently used commercial catalysts can be incorporated in the structure of perovskite oxides. Conversely, it is anticipated that perovskite oxides, appropriately formulated, will show catalytic activity for a large variety of chemical conversions. Even though this expectation is by no means a prediction of commercial success in the face of competition by existing catalyst systems, it makes these oxides attractive models in the study of catalytic chemical conversion. By appropriate formulation many desirable properties can be tailored, including the valence state of transition metal ions, the binding energy and diffusion of O in the lattice, the distance between active sites, and the magnetic and conductive properties of the solid.

Only a very small fraction of possible perovskite formulations have been explored as catalysts. It is expected that further investigation will greatly expand the scope of perovskite catalysis, extend the understanding of solid-state parameters in catalysis, and contribute to the development of practical catalytic processes.
Prospects for District Heating in the United States
Authors: Karkheck J. , Powell J. , Beardsworth E.
Published: October 2006

Large-scale district heating, using waste heat rejected by electric power plants and other sources, is presented as a means of reducing significantly the amount of fossil fuel consumed for residential and commercial space and water heating in the United States. Analysis of the technical and economic aspects of model district heating systems for nine U.S. urban areas shows that district heat service to residential and commercial consumers would be economically attractive. Projections of national service levels show that up to half of the U.S. population could be served by district heating at costs that are competitive with the present costs of imported oil and also with projected costs of new energy forms. An advantage of district heat over the latter is that it is a proved, simple technology.
Lunar Soil: Iron and Titanium Bands in the Glass Fraction
Authors: Wells Ed , Hapke Bruce
Published: October 2006

A study of absorption bands in simulated lunar glasses resulted in the discovery of a Ti
4+
-O
2–
charge transfer band at 0.26 micrometer and two Fe
2+
-Ti
4+
bands at 0.34 and 0.42 micrometer. These results indicate that the properties of lunar soil are somewhat affected by the glass content but are controlled by other factors.
Sulfate Aerosol: Its Geographical Extent in the Midwestern and Southern United States
Authors: Weiss R. E. , Waggoner A. P. , Charlson R. J. , Ahlquist N. C.
Published: October 2006

Sulfate particles (sulfuric acid and its neutralization products with ammonia) dominate the submicrometer-sized, light-scattering component of the aerosol in more than 90 percent of 2850 pairs of humidographic measurements made over a 3-month period at three rural midwestern and southern sites. The nearly continuous optical dominance by sulfate in the aerosol at these spatially varied locations, particularly in the Ozark Mountains, suggests that sulfate is a component of the submicrometer-sized aerosol that is distributed over a large geographical region and is not due to local sources.
A Cheetah-Like Cat in the North American Pleistocene
Authors: Martin Larry D. , Gilbert B. M. , Adams Daniel B.
Published: October 2006

The discovery of abundant skeletal remains of
Felis trumani
from a late Pleistocene deposit in Wyoming shows that it was as highly modified for cursorial locomotion as the cheetah (
Acinonyx
). Several other Pleistocene felids that have been regarded as pumas seem to be related forms. The late Pleistocene fauna of the Big Horn Basin in Wyoming is dominated by cursorial taxa.
The Impact of Integrated Electronics in Medicine
Authors: White Robert L. , Meindl James D.
Published: October 2006

There are two salient points which convey the essence of the impact of integrated electronics in medicine. First, the quality and availability of health care are becoming increasingly dependent on radically new diagnostic, monitoring, and prosthetic instruments provided by electronics. Second, many of these new instruments, such as ultrasonic imaging systems, blood flowmeters, and artificial inner ears, impose very stringent performance requirements, which can be met only through innovative application of integrated electronics. In summary, the initial impact of integrated electronics on health care is now visible, and consequently it is apparent that we are beginning a new era of revolutionary advances in medical instrumentation. Health care may indeed present the most promising opportunity to improve the quality of life in our society through electronics.
New Memory Technologies
Authors: Rajchman Jan A.
Published: October 2006

Computers today use a hierarchy of large-capacity, relatively slow mechanically accessed memories in conjunction with fast electronically accessed memories of relatively small capacity. While the gap between these is spanned by ingenious organizations and programming, it would be highly desirable to fill it instead by some device of sufficient capacity and speed. Candidates for gap-filling memories include metal oxide semiconductor (MOS) random-access memories (RAM's) made by large-scale integration (LSI); charge-coupled devices; magnetic bubble devices based on cylindrical domains of magnetization; electron beam-addressed memories; and optical memories based on lasers, holography, and electrooptical effects. At present, the MOS RAM is the prime contender. Its natural evolution and the evolution of magnetic-recording techniques on which mass storage is based are likely to continue to shape the future as they have for more than a decade. On the other hand, radically new technologies, still at an early laboratory stage, are aimed at a more ideal solution than today's hierarchy.
Regional Specialization of Reptilian Scale Surfaces: Relation of Texture and Biologic Role
Authors: Gans Carl , Baic Dusan
Published: October 2006

The iridescent body scales of the fossorial uropeltid snakes produce these interference colors by keratinous ridges spaced at 2500 Å. The pattern inhibits wetting of the surface and adhesion of soil particles and thus reduces friction between the snake's trunk and walls of its tunnel. The epidermal scales of the blunt tail show a sharply defined pattern of spines and ridges with convergent flutings. Dirt caught here forms a plug that protects the snake's caudal end. The sharp transition of surface textures suggests (i) that selection for each of the two roles is great, and (ii) that the interference colors of many fossorial snakes indicate that friction as well as dirt adhesion are being reduced.
Radioisotope Dating with a Cyclotron
Authors: Muller Richard A.
Published: October 2006

By considering radioisotope dating as a problem in trace element detection, and by using the cyclotron as a high-energy mass spectrometer for this purpose, we have shown that one can greatly increase the maximum age that can be determined while simultaneously reducing the size of the sample required. The cyclotron can be used to detect atoms or simple molecules that are present at the 10
-16
level or greater. For
14
C dating one should be able to go back 40,000 to 100,000 years with 1- to 100-mg carbon samples; for
10
Be dating, 10 to 30 million years with 1-mm
3
to 10-cm
3
rock samples; for tritium dating, 160 years with a 1-liter water sample. The feasibility of the technique has been demonstrated experimentally by measuring the tritium/deuterium ratio in a sample 24 years old. For samples many half-lives old, the fractional error in the age is small even if rates of production or deposition of the isotopes.

Although cyclotrons are expensive to build, their operating costs are relatively low. If several samples are dated per hour the cost per date may not be substantially higher than it is today for decay dating. There are already more than 50 cyclotrons in operation which have the potential to do radioisotope dating, and their application to important problems of dating and trace element analysis should prove very fruitful.
Territorial Division: The Least-Time Constraint Behind the Formation of Subnational Boundaries
Authors: Stephan G. Edward
Published: October 2006

Nations usually locate their smaller administrative subdivisions in regions of highest population density. This report derives a precise form of the size-density relationship from the general assumption that social structures evolve in such a way as to minimize the total time expended by society in their operation. The result is confirmed empirically.
Anomalous Temperature Dependence for a Partial Vapor Pressure
Authors: Roberts James A. , Searcy Alan W.
Published: October 2006

In a limited temperature range the partial pressure of gallium subsulfide (Ga
2
S) above gallium sesquisulfide (Ga
2
S
3
) increases when the temperature is decreased. The anomaly in the partial pressure is caused by changes with temperature in the equilibrium compositions of two solid phases that coexist at 1228° ± 3°K. At this temperature the solids differ in sulfur content by 0.4 atomic percent sulfur.
Detritus-Based Food Webs: Exploitation by Juvenile Chum Salmon (
Oncorhynchus keta
)
Authors: Sibert J. , Brown T. J. , Healey M. C. , Kask B. A. , Naiman R. J.
Published: October 2006

Harpacticoid copepods are the principal food of chum salmon during the first critical weeks of estuarine life. Heterotrophic food sources are preferentially ingested by harpacticoids. A commercially valuable fisheries resource, usually considered to be planktivorous, is related to a detritus-based, benthically derived food web.
Elk in the Shrub-Steppe Region of Washington: An Authentic Record
Authors: Rickard W. H. , Hedlund J. D. , Fitzner R. E.
Published: October 2006

For the first time in recorded history, the American elk is established in the treeless interior region of Washington. The protective isolation provided by the large buffer zone around the Hanford facilities of the U.S. Energy Research and Development Administration is the important factor in maintenance of suitable habitat for elk.
Nitrogen Budget for an Aggrading Northern Hardwood Forest Ecosystem
Authors: Bormann F. H. , Likens G. E. , Melillo J. M.
Published: October 2006

Long-term analyses of the structure and function of a northern hardwood ecosystem have resulted in measurement of the salient features of the nitrogen cycle. These data allow an evaluation of the importance of the various components and provide a framework for more efficient forest management.
Pyroelectricity and Induced Pyroelectric Polarization in Leaves of the Palmlike Plant
Encephalartos villosus
Authors: Lang Sidney B. , Athenstaedt Herbert
Published: October 2006

Quantitative pyroelectric measurements were made on the leaves of the palmlike plant
Encephalartos
. A pyroelectric response almost 50 times higher than the normal one could be induced by a small bias electric field, offering a means for highly increasing the efficiency of conversion of thermal to electrical energy. No evidence of ferroelectricity was found.
Petrolacosaurus
, the Oldest Known Diapsid Reptile
Authors: Reisz Robert R.
Published: October 2006

Petrolacosaurus
, an Upper Pennsylvanian reptile, presents a combination of features that place it within a distinct family of the Eosuchia while also evidencing strong relationships to the ancestral reptiles. It is therefore the earliest and most primitive representative of the largest assemblage of fossil and living reptiles, collectively called diapsids.
Intermetallic Compounds of the Type MNi
5
as Methanation Catalysts
Authors: Elattar A. , Takeshita T. , Wallace W. E. , Craig R. S.
Published: October 2006

Catalytic reactions of carbon monoxide with hydrogen have been studied in which intermetallic compounds of the formula MNi
5
(where M is thorium, uranium, or zirconium) have been used as the catalysts. The materials perform effectively as methanation catalysts; ThNi
5
has a specific activity exceeding that of a typical commercial oxide-supported methanation catalyst by a factor of about 5. This material also shows superior resistance to hydrogen sulfide poisoning. Nickel, formed as a decomposition product of the MNi
5
intermetallic compound, is probably the active species, but its properties are influenced by the nature of M in the precursor MNi
5
system.
Stable Semiconductor Liquid Junction Cell with 9 Percent Solar-to-Electrical Conversion Efficiency
Authors: Chang K. C. , Heller A. , Schwartz B. , Menezes S. , Miller B.
Published: October 2006

The semiconductor liquid junction cell
n
-GaAs/0.8
M
K
2
Se-0.1
M
K
2
Se
2
-1
M
KOH/C has been shown to attain 9 percent photovoltaic power conversion efficiency in sunlight. Accelerated tests under 3100°K light sources of several solar intensities indicate very low photocorrosion currents and high output stability.
Clear Air Turbulence: Detection by Infrared Observations of Water Vapor
Authors: Kuhn P. , Caracena F. , Gillespie C. M.
Published: October 2006

"Forward-looking" infrared measurements of water vapor from the C-141A Kuiper Airborne Observatory of the National Aeronautics and Space Administration Ames Research Center show large, distinctly identifiable, signal anomalies from 4 to 10 minutes in advance of subsequent encounters with clear air turbulence (CAT). These anomalies are characteristically different from the signals not followed by CAT encounters. Results of airborne field trials in which the infrared radiometer was used indicate that, out of 51 situations, 80 percent were CAT alerts followed by CAT encounters, 12 percent were "false alarms" (CAT alerts not followed by CAT encounters), and 8 percent were CAT encounters not preceded by an infrared signal anomaly or CAT alert.
Phyllotaxis in
Xanthium
Shoots Altered by Gibberellic Acid
Authors: Maksymowych Roman , Erickson Ralph O.
Published: October 2006

Gibberellic acid treatment of vegetative
Xanthium
shoots induced a change in phyllotaxis and almost doubled the rate of leaf production. Phyllotaxis in control plants displayed a 2,3 contact parastichy pattern; that of the treated plants could be approximated with a 3,5 pattern. Thus, the
Xanthium
apex switched to a new mode of growth and a higher order of phyllotactic leaf arrangement not seen in untreated plants. It may be inferred from these experiments that gibberellic acid plays a role in determining the site of leaf initiation.
Nucleation on Photoexcited Molecules
Authors: Katz Joseph L. , Wen F. C. , McLaughlin Timothy , Reusch Robert J. , Partch Richard
Published: October 2006

On irradiation with light of suitable wavelength and intensity, certain organic compounds, even at very low concentrations, cause very efficient nucleation of supersaturated vapors. A mechanism is suggested to account for this phenomenon. Nuclei containing only a few photoexcited molecules are responsible for the nucleation.
Polarity Transition Records and the Geomagnetic Dynamo
Authors: Hoffman Kenneth A.
Published: October 2006

The Parker-Levy approach to reversals of the geomagnetic field predicts meridional transitional paths of the virtual geomagnetic pole (VGP) which pass either through the site of observation or through its antipode, depending upon the site location and the sense of the polarity transition. Comparison with the most detailed transitional VGP path records presently available gives some indication of the above behavior as predicted by the Parker-Levy model. Discrepancies may be due to complexities in the distribution of cyclonic convection cells in the core not considered in the formal mathematical treatment. The predicted variation in transitional field intensity experienced at any given site also is compatible with several reported transition records.
Rapid Response to Selection for a Nondiapausing Gypsy Moth
Authors: Hoy Marjorie A.
Published: October 2006

By genetic selection a gypsy moth strain was obtained within eight generations that could be reared continuously in the insectary without its normal "obligatory" diapause. This strain should be useful for making physiological and genetical comparisons with normal diapausing gypsy moths. It could also be used in a genetic control program. However, caution should be exercised, for its release could create a new environmental hazard.
Radiocarbon Dating Using Electrostatic Accelerators: Negative Ions Provide the Key
Authors: Bennett C. L. , Beukens R. P. , Clover M. R. , Gove H. E. , Liebert R. B. , Litherland A. E. , Purser K. H. , Sondheim W. E.
Published: October 2006

Mass spectrometric methods have long been suggested as ways of measuring
14
C/
12
C ratios for carbon dating. One problem has been to distinguish between
14
N and
14
C. With negative ions and a tandem electrostatic accelerator, the
14
N background is virtually absent and fewer than three
14
C atoms in 10
16
atoms of
12
C have been easily measured.
A Synthetic Congener Modeled on a Microbicidal Domain of Thrombin- Induced Platelet Microbicidal Protein 1 Recapitulates Staphylocidal Mechanisms of the Native Molecule
Authors: Xiong Yan Q. , Bayer Arnold S. , Elazegui Lisa , Yeaman Michael R.
Published: October 2006

Thrombin-induced platelet microbicidal protein 1 (tPMP-1) is a staphylocidal peptide released by activated platelets. This peptide initiates its microbicidal activity by membrane permeabilization, with ensuing inhibition of intracellular macromolecular synthesis. RP-1 is a synthetic congener modeled on the C-terminal microbicidal α-helix of tPMP-1. This study compared the staphylocidal mechanisms of RP-1 with those of tPMP-1, focusing on isogenic tPMP-1-susceptible (ISP479C) and -resistant (ISP479R)
Staphylococcus aureus
strains for the following quantitative evaluations: staphylocidal efficacy; comparative MIC; membrane permeabilization (MP) and depolarization; and DNA, RNA, and protein synthesis. Although the proteins had similar MICs, RP-1 caused significant killing of ISP479C (<50% survival), correlating with extensive MP (>95%) and inhibition of DNA and RNA synthesis (>90%), versus substantially reduced killing of ISP479R (>80% survival), with less MP (55%) and less inhibition of DNA or RNA synthesis (70 to 80%). Interestingly, RP-1-induced protein synthesis inhibition was equivalent in both strains. RP-1 did not depolarize the cell membrane and caused a relatively short postexposure growth inhibition. These data closely parallel those previously reported for tPMP-1 against this strain set and exemplify how synthetic molecules can be engineered to reflect structure-activity relationships of functional domains in native host defense effector molecules.
Acquired Gentamicin Resistance by Permeability Impairment in
Enterococcus faecalis
Authors: Aslangul Elisabeth , Massias Laurent , Meulemans Alain , Chau Françoise , Andremont Antoine , Courvalin Patrice , Fantin Bruno , Ruimy Raymond
Published: October 2006

Enterococci are intrinsically resistant to low levels of aminoglycosides. We previously selected in vitro and in vivo
Enterococcus faecalis
with intermediate-level resistance to gentamicin that did not abolish synergism with a cell-wall-active agent (E. Aslangul et al., Antimicrob. Agents Chemother. 49:4144-4148, 2005). The aim of this study was to investigate the mechanism of resistance to gentamicin in the 1688-G3 third-step mutant (MIC, 512 μg/ml) of
E. faecalis
JH2-2. No mutations were found in the genes for L6 ribosomal protein and the four copies of 16S rRNA. Production of a known aminoglycoside-modifying enzyme was unlikely due to the distinct resistance phenotype and absence of the corresponding genes. Efflux was also unlikely since ethidium bromide MICs were similar for JH2-2 and 1688-G3 and since the pump inhibitors reserpine and verapamil had no effect on gentamicin resistance in both strains. To study gentamicin accumulation, we developed a nonisotopic method based on a fluorescent polarization immunoassay. Impaired gentamicin accumulation was observed in 1688-G3 compared to JH2-2 and was only partially reversible by the
N
,
N
′-dicyclohexylcarbodiimide (DCCD) uncoupler agent. The lower sensitivity of 1688-G3 to DCCD suggested alteration of the F
o
F
1
-ATPase. However, no mutations were detected in the structural genes (
atp
) for the F
o
channel and no difference in transcript levels of
atpB
and
atpE
was found between 1688-G3 and JH2-2. Our data are compatible with acquisition of intermediate-level gentamicin resistance by uptake impairment in
E. faecalis
.
Pharmacokinetic-Pharmacodynamic Relationship of Arbekacin for Treatment of Patients Infected with Methicillin-Resistant
Staphylococcus aureus
Authors: Sato Reiko , Tanigawara Yusuke , Kaku Mitsuo , Aikawa Naoki , Shimizu Kihachiro
Published: October 2006

Arbekacin is widely used in Japan for the treatment of patients infected with methicillin-resistant
Staphylococcus aureus
(MRSA). In this study, we have determined the optimal concentration targets of arbekacin for both efficacy and safety. A pharmacokinetic-pharmacodynamic analysis was performed to relate exposure to the drug and clinical cure/improvement or nephrotoxicity. Since we have reported the population pharmacokinetic parameters for arbekacin in the preceding paper (Y. Tanigawara, R. Sato, K. Morita, M. Kaku, N. Aikawa, and K. Shimizu, Antimicrob. Agents Chemother. 50:3754-3762, 2006), individual exposure parameters, such as area under the concentration-time curve (AUC), peak concentration (
C
max
), AUC/MIC,
C
max
/MIC, and trough concentration (
C
min
) were estimated by the Bayesian method. Logistic regression was used to describe the relationship between exposure to the drug and the probability of clinical cure/improvement or nephrotoxicity. For the clinical efficacy analysis, 174 patients confirmed to have an MRSA infection were evaluated. The
C
max
,
C
min
, and AUC of arbekacin were associated with the probability of clinical cure/improvement during monotherapy. It was shown that the probability of cure/improvement rose when the
C
max
of arbekacin was increased, with an odds ratio of 6.7 for a change in
C
max
from 7.9 to 12.5 μg/ml (
P
= 0.037). For the nephrotoxic risk analysis, 333 patients were included, regardless of whether a pathogen was identified. Logistic regression analysis revealed
C
min
and AUC as risk factors of nephrotoxicity (
P
< 0.005). The estimated probabilities of arbekacin-induced nephrotoxicity were 2.5, 5.2, and 13.1% when the
C
min
values were 1, 2, and 5 μg/ml, respectively. The present findings are useful for optimizing the individual dose of arbekacin for the treatment of MRSA-infected patients.
Suppression of Gastric Acid Production by Proton Pump Inhibitor Treatment Facilitates Colonization of the Large Intestine by Vancomycin-Resistant
Enterococcus
spp. and
Klebsiella pneumoniae
in Clindamycin-Treated Mice
Authors: Stiefel Usha , Rao Agam , Pultz Michael J. , Jump Robin L. P. , Aron David C. , Donskey Curtis J.
Published: October 2006

Proton pump inhibitor treatment of clindamycin-treated mice elevated the gastric pH and facilitated the establishment of colonization of the large intestine by vancomycin-resistant
Enterococcus
spp. (75 to 80%, versus 20 to 25% for saline-treated controls) and
Klebsiella pneumoniae
(90%, versus 30% for saline-treated controls). These findings demonstrate a mechanism by which proton pump inhibitor therapy could contribute to the dissemination of nosocomial pathogens.
Inhibition of Multiple Subtypes of Influenza A Virus in Cell Cultures with Morpholino Oligomers
Authors: Ge Qing , Pastey Manoj , Kobasa Darwyn , Puthavathana Piliapan , Lupfer Christopher , Bestwick Richard K. , Iversen Patrick L. , Chen Jianzhu , Stein David A.
Published: October 2006

Peptide-conjugated phosphorodiamidate morpholino oligomers (P-PMO) are single-stranded nucleic acid-like antisense agents that can reduce gene expression by sterically blocking complementary RNA sequence. P-PMO are water soluble and nuclease resistant, and they readily achieve uptake into cells in culture under standard conditions. Eight P-PMO, each 20 to 22 bases in length, were evaluated for their ability to inhibit influenza A virus (FLUAV) A/PR/8/34 (H1N1) replication in cell culture. The P-PMO were designed to base pair with FLUAV RNA sequences that are highly conserved across viral subtypes and considered critical to the FLUAV biological-cycle, such as gene segment termini and mRNA translation start site regions. Several P-PMO were highly efficacious, each reducing viral titer in a dose-responsive and sequence-specific manner in A/PR/8/34-infected cells. Two P-PMO, one designed to target the AUG translation start site region of PB1 mRNA and the other the 3′-terminal region of nucleoprotein viral genome RNA, also proved to be potent against several other FLUAV strains, including A/WSN/33 (H1N1), A/Memphis/8/88 (H3N2), A/Eq/Miami/63 (H3N8), A/Eq/Prague/56 (H7N7), and the highly pathogenic A/Thailand/1(KAN-1)/04 (H5N1). The P-PMO exhibited minimal cytotoxicity in cell viability assays. High efficacy by two of the P-PMO against multiple FLUAV subtypes suggests that these oligomers represent a broad-spectrum therapeutic approach against a high percentage of known FLUAV strains.
Candida albicans
Biofilms Produce Antifungal-Tolerant Persister Cells
Authors: LaFleur Michael D. , Kumamoto Carol A. , Lewis Kim
Published: October 2006

Fungal pathogens form biofilms that are highly recalcitrant to antimicrobial therapy. The expression of multidrug resistance pumps in young biofilms has been linked to increased resistance to azoles, but this mechanism does not seem to underlie the resistance of mature biofilms that is a model of in vivo infection. The mechanism of drug resistance of mature biofilms remains largely unknown. We report that biofilms formed by the major human pathogen
Candida albicans
exhibited a strikingly biphasic killing pattern in response to two microbicidal agents, amphotericin B, a polyene antifungal, and chlorhexidine, an antiseptic, indicating that a subpopulation of highly tolerant cells, termed persisters, existed. The extent of killing with a combination of amphotericin B and chlorhexidine was similar to that observed with individually added antimicrobials. Thus, surviving persisters form a multidrug-tolerant subpopulation. Interestingly, surviving
C. albicans
persisters were detected only in biofilms and not in exponentially growing or stationary-phase planktonic populations. Reinoculation of cells that survived killing of the biofilm by amphotericin B produced a new biofilm with a new subpopulation of persisters. This suggests that
C. albicans
persisters are not mutants but phenotypic variants of the wild type. Using a stain for dead cells, rare dark cells were visible in a biofilm after amphotericin B treatment, and a bright and a dim population were physically sorted from this biofilm. Only the dim cells produced colonies, showing that this method allows the isolation of yeast persisters. Given that persisters formed only in biofilms, mutants defective in biofilm formation were examined for tolerance of amphotericin B. All of the known mutants affected in biofilm formation were able to produce normal levels of persisters. This finding indicates that attachment rather than formation of a complex biofilm architecture initiates persister formation. Bacteria produce multidrug-tolerant persister cells in both planktonic and biofilm populations, and it appears that yeasts and bacteria have evolved analogous strategies that assign the function of survival to a small part of the population. In bacteria, persisters are dormant cells. It remains to be seen whether attachment initiates dormancy that leads to the formation of fungal persisters. This study suggests that persisters may be largely responsible for the multidrug tolerance of fungal biofilms.
23S rRNA 2058A→G Alteration Mediates Ketolide Resistance in Combination with Deletion in L22
Authors: Berisio Rita , Corti Natascia , Pfister Peter , Yonath Ada , Böttger Erik C.
Published: October 2006

Resistance to macrolides and ketolides occurs mainly via alterations in RNA moieties of the drug-binding site. Using an A2058G mutant of
Mycobacterium smegmatis
, additional telithromycin resistance was acquired via deletion of 15 residues from protein L22. Molecular modeling, based on the crystal structure of the large ribosomal subunit from
Deinococcus radiodurans
complexed with telithromycin, shows that the telithromycin carbamate group is located in the proximity of the tip of the L22 hairpin-loop, allowing for weak interactions between them. These weak interactions may become more important once the loss of A2058 interactions destabilizes drug binding, presumably resulting in a shift of the drug toward the other side of the tunnel, namely, to the vicinity of L22. Hence, the deletion of 15 residues from L22 may further destabilize telithromycin binding and confer telithromycin resistance. Such deletions may also lead to notable differences in the tunnel outline, as well as to an increase of its diameter to a size, allowing the progression of the nascent chain.
Thymidine Kinase Mutations Conferring Acyclovir Resistance in Herpes Simplex Type 1 Recombinant Viruses
Authors: Sergerie Yan , Boivin Guy
Published: October 2006

Contributions of thymidine kinase (TK) mutations to acyclovir (ACV) resistance were evaluated in herpes simplex virus type 1 recombinant viruses generated using a set of overlapping cosmids and plasmids. Alterations in both conserved and nonconserved regions of the TK gene were shown to confer high levels of resistance to ACV.
In Vitro Killing of Nosocomial Pathogens by Acid and Acidified Nitrite
Authors: Rao Agam , Jump Robin L. P. , Pultz Nicole J. , Pultz Michael J. , Donskey Curtis J.
Published: October 2006

Exposure to pH 1 or 2 buffers or acidic gastric contents resulted in the killing of vancomycin-resistant
Enterococcus
sp.,
Klebsiella pneumoniae
,
Staphylococcus aureus
, and
Candida glabrata
but not
Clostridium difficile
spores. Nitrite enhanced killing under acidic conditions, but significant killing of
C. difficile
spores required nitrite concentrations above usual physiological levels.