bluuebunny/crossref_metadata_2025 huggingface dataset:
Variability of the relationship between particle size and cloud‐nucleating ability
Authors: Hudson James G.
Published: April 2007

Cloud condensation nuclei (CCN) are characterized by their critical supersaturation (Sc), which is a function of particle size and chemistry, namely water solubility. Measurements that relate particle size to Sc can thus be used to determine CCN solubility. A sufficiently small degree of variability of size‐Sc measurements has been cited as evidence that CCN can be deduced from particle size measurements alone. Since particle size is so much easier to measure than particle chemistry or CCN this would have significant advantages for investigations of the largest climate uncertainty, the indirect aerosol effect; e.g., remote sensing of CCN. However, we present size‐Sc measurements with a greater range of variability, which appears to at least limit or cast doubts on the practicality of deducing CCN from particle size measurements.
Latitudinal distribution of aerosol black carbon and its mass fraction to composite aerosols over peninsular India during winter season
Authors: Moorthy K. Krishna , Babu S. Suresh , Badarinath K. V. S. , Sunilkumar S. V. , Kiranchand T. R. , Ahmed Y. Nazeer
Published: April 2007

During a land campaign to characterise the spatial distribution of aerosols over peninsular India during the winter season, extensive, collocated, and spatially resolved measurements of mass concentration of the composite aerosols (MT) as well as that (MB) of aerosol Black Carbon (BC) were made over different environments (coastal, industrial, urban, village, remote, semiarid) of the western peninsular India. High concentrations of BC, >2.5 μg m−3, were observed along the west coast, from ∼8°N up to 14.5°N, and moderate values (1.0 to 2.5 μg m−3) over inland regions from 15 to 18°N. Latitudinally, BC concentration decreased from south to north, @∼160 ng m−3 for every degree increase in latitude. The spatial pattern of BC mass fraction differed from that of MB, with regions of high (8 to 16%) ratios spreading more interior, implying higher fractional load of BC at locations where the BC concentrations remain lower.
Mantle wehrlite from Hess Deep as a crystal cumulate from an ultra‐depleted primary melt in East Pacific Rise
Authors: Arai S. , Takemoto Y.
Published: April 2007

A piece of wehrlite, containing about 20 volume % of clinopyroxene, was found in harzburgite in a drill core of ODP Leg 147 from Hess Deep near the East Pacific Rise. Minerals are as refractory (olivine, Fo90.7; spinel, Cr# = 0.52) as those in the harzburgite. The clinopyroxene is depleted in REE (rare earth elements), being similar in chondrite‐normalized pattern for middle to heavy REE to that of the harzburgite. The calculated melt in equilibrium with the clinopyroxene is as depleted as ultra‐depleted MORB melts ever documented. The wehrlite is a cumulate from an in‐situ segregated ultra‐depleted MORB melt. Dimension of individual masses of the ultra‐depleted MORB involved may be at least as large as a few tens of centimeters. The Hess Deep wehrlite is different from the lower crustal wehrlite from the ocean floor or some ophiolites, which is either a cumulate or a peridotite/melt reaction product.
Upper‐ocean response to Hurricane Ivan in a 1/25° nested Gulf of Mexico HYCOM
Authors: Prasad T. G. , Hogan Patrick J.
Published: April 2007

A 20‐layer, 1/25° nested Gulf of Mexico (GoM) Hybrid Coordinate Ocean Model (HYCOM) has been employed to examine the evolving three‐dimensional ocean response to Hurricane Ivan during 14–16 September 2004. Results from several combinations of numerical experiments with and without assimilation of satellite‐altimetry sea‐surface height (SSH) are being analyzed and compared for the September 2004 hurricane period. A comparison of simulated zonal and meridional velocities using data assimilation shows improved agreement with profiler observations. The amplitude of the cold wake (∼6°C) produced by these simulations compared reasonably well with the observed changes in SST before and after the storm; however, the region of extreme cooling varied depending on the simulated location of the warm core eddy (WCE) that had detached from the Loop Current (LC). While the simulated location of the WCE and LC in the assimilation runs agree better with satellite altimetry, the storm‐induced SST cooling was 40%–50% greater than the observed cooling. Overall, ∼64% of the cooling was due to vertical mixing caused by turbulence generated from strong shear‐stress across the base of the mixed layer. Vertical advection (upwelling) caused a significant portion of cooling (23.4%) in those runs that included data assimilation; a three fold increase from the nonassimilative runs (7%). This enhanced upper‐ocean cooling was caused primarily by the prestorm thermal stratification; a shallower thermocline (∼40 m) and a stronger upper‐thermocline temperature gradient compared with the nonassimilative runs. In all the experiments the air‐sea exchange was a small component of the mixed‐layer heat budget which overall accounted for ∼4%.
Stratospheric ozone isotope fractionations derived from collected samples
Authors: Krankowsky D. , Lämmerzahl P. , Mauersberger K. , Janssen C. , Tuzson B. , Röckmann T.
Published: April 2007

Oxygen isotope ratios in ozone show an unusual enrichment when compared with expected values. New results are reported that have been determined from samples collected in the stratosphere on board balloons. Flights were conducted from three locations, near the equator, at middle latitudes, and in the polar region. To about 27 km the temperature of the atmosphere determines the isotope enrichment of the two heavy isotopes 49O3 and 50O3; above that altitude the enrichments increase more strongly. Highest values measured near the equator are 13% in 50O3 and 10% in 49O3 around 32 km, implying an additional photolysis‐induced isotope effect which accounts for 1/4 of the total enrichments measured. Results above Kiruna, Sweden, show a marked increase in heavy ozone from early winter to early summer in agreement with laboratory studies which established the significance of the gas temperature during ozone production. The new data quantitatively establish an additional enrichment in heavy ozone for the upper stratosphere. It is more pronounced near the equator than at middle latitudes and was not detectable in the polar region.
Hurricane‐climate change link unclear
Authors: Zielinski Sarah
Published: April 2007

Evidence exists both for and against an influence of anthropogenic climate change on any increased hurricane activity, and no conclusion can be drawn at this time as to whether or not a link exists, an international group of hurricane researchers concluded in a statement released on 4 December 2006.

More than 120 researchers from 34 countries met at the Sixth World Meteorological Organization International Workshop on Tropical Cyclones, which was held at the end of November in San José, Costa Rica. The workshop participants decided to develop the consensus statement because of increased attention to the subject due to several high‐impact tropical cyclone events around the globe, such as the active 2004 and 2005 Atlantic hurricane seasons.
New AGU fellows
Authors: Anonymous
Published: April 2007

With a new total membership high of just over 48,000, it was possible to elect 48 new Fellows for the 2007 class. Fellows of AGU are members who have attained acknowledged eminence in Earth and space sciences. They are nominated by colleagues, vetted by the relevant sections or in some cases focus groups, and then elected by the Union Fellows Committee, which comprises 11 Fellows. Only 0.1% of the membership can be elected each year.
Environmental standards needed for offshore marine aquaculture
Authors: Zielinski Sarah
Published: April 2007

The U.S. Congress should enact legislation that sets strong environmental standards for offshore marine aquaculture, the Marine Aquaculture Task Force recommended in a recent report. Aquaculture now accounts for about half of all seafood consumed in the world, and the industry is rapidly growing and expanding into regions offshore (more than 3 nautical miles from the coast) that are controlled by the federal government. The task force, which was organized by researchers from the Woods Hole Oceanographic Institution, examined the risks and benefits of marine aquaculture. They proposed that the U.S. National Oceanic and Atmospheric Administration be appointed the lead agency responsible for regulation of offshore marine aquaculture and for providing incentives for research and development. The main environmental standard proposed by the task force was to limit farming only to native species with local genetics unless the potential harm of escaped fish to local populations would be negligible.
Enhancing geoscience education in public schools
Authors: Silliman James , Hansen Alan , McDonald JoAnn , Blount Kit Price , Hill Denise , Martinez Mayra
Published: April 2007

Positive experiences are crucial to student learning as well as in deciding what career to pursue [Jacobs et al., 1998]. U.S. National Science Foundation (NSF) studies have shown that by the time students enter high school, 80% are not interested in pursuing science, mathematics, or engineering [NSF, 2002]. Moreover, students without a sufficient background in mathematics and science by the sixth grade will be unable to take advantage of necessary high school classes for college preparation in technological areas [NSF, 2002]. If students have positive experiences earlier, these experiences will be of greater benefit to them in learning and in making important life decisions.

The Cabeza de Vaca Earthmobile program enhances geoscience learning among middle school students while fostering a supportive learning environment.
A perspective on global warming, dimming, and brightening
Authors: Stanhill Gerald
Published: April 2007

Heated discussion of climate change is not a new feature of public debate, as Fleming [1998] has demonstrated in his studies of the historical perspectives of this topic. Nevertheless, a strong case can be made that the current level of public concern and even apprehension may be unprecedented. The purpose of this article is to draw attention to the challenge that recently reported changes in solar radiation at the Earth's surface, Eg↓, pose to the consensus explanation of climate change.
Storm impacts on potential pathogens in estuaries
Authors: Fries J. Stephen , Noble Rachel T. , Kelly Ginger M. , Hsieh Jennifer L.
Published: April 2007

Estuarine and coastal environments are susceptible to a variety of changes driven by tropical storms and hurricanes. The 2005 Atlantic hurricane season impressed upon the public the devastating impacts of storms on coastal populations and the possible social and public health costs. Storm surges and subsequent flooding have the potential to redistribute water and associated contaminants, including a wide range of chemicals and microorganisms. While this impact is difficult to observe through monitoring during larger storms, smaller storms provide opportunities to observe the mechanisms responsible for contaminant and microbial transport.
Volcano Web site wins award
Authors: Zielinski Sarah
Published: April 2007

Hero of Vesuvius' received the 2006 Best Website Award from the Geoscience Information Society. The site (http://www.vesuvius. tomgidwitz.com/html/the_hero_of_vesuvius.html) documents the life and work of American inventor and volcanologist Frank Alvord Perret.
Outstanding student paper awards
Authors: Anonymous
Published: April 2007

The following members received Outstanding Student Paper Awards at the 2006 Fall Meeting in San Francisco, Calif. Winners in other sections and focus groups will be announced in subsequent issues of Eos.
Future directions in subglacial environments research
Authors: Kennicutt Mahlon , Petit Jean‐Robert
Published: April 2007

Subglacial Antarctic Lake Environments (SALE) exploration and study is poised to be a major focus of Antarctic science for the next decade or more. The foundation for an intensive period of SALE research and field efforts has been provided by substantial improvement in our understanding of these environments, the establishment of SALE research programs by the International Polar Year (IPY) Program Office and the Scientific Committee on Antarctic Research (SCAR), the funding of several national SALE programs, independent guidance on environmental stewardship issues, and a series of international workshops, meetings, and conferences that have refined SALE scientific objectives. This article summarizes recent developments in subglacial environment exploration and study and describes future research needs.

In the 7 years since the report “Subglacial Lake Exploration: Workshop and Recommendations” (SCAR International Workshop, Cambridge, U.K., September 1999), our understanding of subglacial environments has greatly improved. Subglacial environments are continental‐scale phenomena that occur under thick ice sheets [Siegert et al., 2005]. The importance and role of subglacial water are now recognized as central to many processes that have shaped the Antarctic continent and its ice sheets today and in the past. Subglacial environments include a range of features that differ in geologic setting, age, evolutionary history, limnological conditions, and size [Bell, 2006]. These environments are ‘natural’ Earth‐bound macrocosms that in some instances trace their origins to a time before Antarctica became encased in ice [Bell, 2006].
Online database of European marine research projects
Authors: Zielinski Sarah
Published: April 2007

EurOcean‐European Centre for Information on Marine Science and Technology has created an online database (available at http://euroceanmrfp.addition.pt) of 516 marine research projects funded by various European entities. Eur‐Ocean is a program intended to facilitate access to information and encourage cooperation between European organizations involved in marine research.
[Comment on “A turning point in auroral physics”] Origin of auroral arcs
Authors: Stern David P.
Published: April 2007

In an article in Eos (57(39), 403, 26 September 2006), Duncan Bryant claimed “a turning point in auroral physics.” He credited the polar aurora to waves generated when positive tail ions interact with flanks of the magnetosphere. Unfortunately, auroral arcs need a stronger energy source, and electrons from the tail have a hard time penetrating the loss cone. The process could perhaps contribute to the electrons of 500–1000 eV in the plasma sheet, where their gradual escape creates the diffuse aurora observed by satellites, but not create the bright auroral arcs seen from the ground.
Eos change
Authors: Geissman John , Gordon Wendy , Grande Manuel , Spilhaus Fred , Virji Hassan
Published: April 2007

Eos is and has long been the glue that binds the Union together. The newspaper must continue to serve the great breadth of scientific interests represented by the many sections and focus groups as well as AGU's diverse, worldwide membership. To do this job well poses many challenges. One of these is balancing the subjects covered so that all scientific interests of the membership are represented with reasonable frequency in the first pages of Eos.
2006 Horton (Hydrology) Research Grant recipients
Authors: Anonymous
Published: April 2007

The 2006 Horton (Hydrology) Research Grant Committee selected two recipients, Xingyuan Chen and Carl Legleiter. The research grant, which is separate from the Horton Award, supports projects in hydrology and water resources by doctoral candidates at institutions of higher learning.

The grant's objective is to foster graduate student research leading to the completion of doctoral dissertations. Both recipients were formally awarded at the 2006 AGU Fall Meeting, in San Francisco, California.
NASA reports on near‐Earth objects program
Authors: Zielinski Sarah
Published: April 2007

A nuclear explosion could be the surbest option for deflecting an asteroid headed for Earth, according to a NASA report to the U.S. Congress that was released on 9 March. Other options could be used, particularly in the case of a small, solid body, but the report notes that 30–80% of potentially hazardous near‐Earth objects are in orbits that cannot be reached by current or planned launch systems. The report also finds that in order for NASA to reach its congressionally mandated goal of finding 90% of all potentially hazardous near‐Earth objects by 2020, the agency will need to partner with other government agencies on future groundbased observatories and that one observatory will need to be dedicated to the discovery of these objects.
Legislation proposed to enhance high school science labs
Authors: Zielinski sarah
Published: April 2007

At an 8 March hearing, the U.S. House of Representatives Science and Technology Subcommittee on Research and Education began consideration of new legislation intended to improve high school science laboratories. The bill, H.R. 524, would create a $5 million program at the U.S. National Science Foundation that would provide grants to improve high school science laboratories. The grants could be used to purchase or rent equipment and instrumentation, maintain or renovate facilities, train teachers, or design hands‐on laboratory experiences.
Evaluating the impacts of aviation on climate change
Authors: Wuebbles Don , Gupta Mohan , Ko Malcolm
Published: April 2007

Aviation is an integral part of the global economic and transportation systems. In fact, aviation expansion outpaces the economic growth. Projections indicate that over the next 2 decades, the demand for aviation could grow to about 3 times its present level. This projected growth will likely result in higher aviation emissions and associated impacts on the environment and on human health and welfare, depending upon a variety of factors (such as the size and mix of the operational fleet necessary to meet the stated demand, as well as mitigation steps that could include new technological advances, more efficient operational procedures, market‐based options, or regulatory intervention). Nonetheless, it is critical to balance the economic benefits of air travel with environmental concerns associated with this projected aviation growth.
[Comment on “Bringing space physics concepts into introductory electromagnetism”] On the concept of moving magnetic fields lines
Authors: Fälthammar Carl‐Gunne , Mozer Forrest S.
Published: April 2007

More than 99% of the known matter in the universe is ionized into the plasma state. This cosmical plasma is generally permeated by magnetic fields. Hence, magnetic fields, and the concepts of magnetic field lines and magnetic field line motion, are of fundamental interest in the physics of space plasmas, including those that constitute the near environment of the Earth and other planets.

W. Belcher discussed the concept of magnetic field line motion as a useful tool in teaching electromagnetic theory in an article in Eos [Belcher, 2005]. However, there are some important limitations and pitfalls to this concept, none of which is mentioned in the article by Belcher.
University satellites and space science education
Authors: Crosby Norma B. , Krasotkin Serge , Haubold Hans J.
Published: April 2007

Global society increasingly is dependent on reliable space satellite systems that are resistant to hazards present in the space environment. Therefore, it is essential that the present young generation, as well as future ones, be educated in satellite technology as well as in the space sciences. These multidisciplinary subjects cover a wide range of topics in science, engineering, medicine, environment, finance, and so forth. In regard to teaching activities, these subjects offer many unique opportunities, such as teaching students the different ‘languages’ of the various subjects so that later in their careers they are better communicators.
The Global Coastal Ocean: Interdisciplinary Regional Studies and Syntheses
Authors: Chen Chen‐Tung Arthur
Published: April 2007

Coastal zones are where land, rivers, atmosphere, seas, sediments, and biota meet, and thus where spatial and temporal heterogeneity is substantial. This volume of The Sea complements and supplements volumes 10 and 11, as well as Part B of Volume 14, which deal generally with the physical oceanography of global coastal oceans, and Volume 13, which examines multiscale interdisciplinary processes on sediment, biogeochemical, and ecosystem dynamics. Because of extreme complexity, however, analyzing and synthesizing in an interdisciplinary manner observations from global coastal oceans is difficult. Because most worldwide observation systems are complicated, many global programs, such as the System for Analysis, Research and Training for Global Change Research (START), the Global Carbon Project (GCP), and the Monsoon Asia Integrated Regional Study (MAIRS), have all promoted regional research for achieving the final goal of global synthesis. This volume takes the same approach.
Hepatoprotective role of PXR activation and MRP3 in cholic acid‐induced cholestasis
Authors: Teng S , Piquette‐Miller M
Published: April 2007

Background and purpose:

Activation of the pregnane X receptor (PXR) has been shown to protect against cholestatic hepatotoxicity. As PXR alters the expression of numerous hepatic bile acid transporters, we sought to delineate their potential role in hepatoprotection.

Experimental approach:

Wild‐type (PXR+/+) and PXR‐null (PXR‐/‐) mice were fed a 1% cholic acid (CA) diet with or without the PXR activator, PCN. Liver function was assessed along with the corresponding changes in hepatic gene expression.

Key results:

CA administration caused significant hepatotoxicity in PXR+/+ mice and was associated with induction of several FXR and PXR regulated genes, which encode for bile acid transport and metabolizing proteins. Compared to CA alone, co‐administration of PCN to CA‐fed PXR+/+ mice significantly decreased hepatotoxicity and was associated with induction of MRP3 mRNA as well as CYP3A11 mRNA and functional activity. Unexpectedly, PXR‐/‐ mice, which expressed significantly higher basal and CA‐induced levels of MRP2, MRP3, OSTα, OSTβ, OATP2 and CYP3A11, were dramatically less sensitive to CA hepatotoxicity than PXR+/+ mice.

Conclusions:

Protection of PXR+/+ mice against CA‐induced hepatotoxicity by PCN is associated with the induction of MRP3 and CYP3A11 expression. Resistance against CA‐induced hepatotoxicity in PXR‐/‐ mice may result from higher basal and induced expression of bile acid transporters, particularly MRP3. These findings emphasize the importance of transport by MRP3 and metabolism as major protective pathways against cholestatic liver injury.

British Journal of Pharmacology (2007) 151, 367–376; doi:10.1038/sj.bjp.0707235
Inhibition of Cyclooxygenases by Dipyrone
Authors: Pierre S C , Schmidt R , Brenneis C , Michaelis M , Geisslinger G , Scholich K
Published: April 2007

Background and Purpose:

Dipyrone is a potent analgesic drug that has been demonstrated to inhibit cyclooxygenase (COX). In contrast to classical COX‐inhibitors, such as aspirin‐like drugs, dipyrone has no anti‐inflammatory effect and a low gastrointestinal toxicity, indicating a different mode of action. Here, we aimed to investigate the effects of dipyrone on COX.

Experimental approach:

The four major metabolites of dipyrone, including the two pharmacologically active metabolites, 4‐methyl‐amino‐antipyrine (MAA) and amino‐antipyrine (AA), were used to characterise their binding to COX and haem as well as their effects on the biochemical properties of COX. Mass spectrometry, UV and visible photometry were used to study binding and prostaglandin production. Levels of anti‐oxidant enzymes were assessed by Western blotting.

Key results:

The pharmacologically active metabolites of dipyrone, MAA and AA, did not inhibit COX activity in vitro like classical COX inhibitors, but instead redirected the prostaglandin synthesis, ruling out inhibition of COX through binding to its active site. We found that MAA and AA formed stable complexes with haem and reacted with hydrogen peroxide in presence of haem, ferrous ions (Fe2+) or COX. Moreover, MAA reduced Fe3+ to Fe2+ and accordingly increased lipid peroxidation and the expression of anti‐oxidant enzymes in cultured cells and in vivo.

Conclusions and implications:

Our data suggest that the pharmacologically active metabolites of dipyrone inhibit COX activity by sequestering radicals which initiate the catalytic activity of this enzyme or through the reduction of the oxidative states of the COX protein.

British Journal of Pharmacology (2007) 151, 494–503; doi:10.1038/sj.bjp.0707239
Characterization of a novel ATP‐sensitive K+channel opener, A‐251179, on urinary bladder relaxation and cystometric parameters
Authors: Shieh C‐C , Brune M E , Buckner S A , Whiteaker K L , Molinari E J , Milicic I A , Fabiyi A C , Daza A , Brioni J D , Carroll W A , Matsushita K , Yamada M , Kurachi Y , Gopalakrishnan M
Published: April 2007

Background and Purpose:

ATP‐sensitive K+channels (KATP) play a pivotal role in contractility of urinary bladder smooth muscle. This study reports the characterization of 4‐methyl‐N‐(2,2,2‐trichloro‐1‐(3‐pyridin‐3‐ylthioureido)ethyl)benzamide (A‐251179) as a KATPchannel opener.

Experimental Approach:

Glyburide‐sensitive membrane potential, patch clamp and tension assays were employed to study the effect of A‐251179in vitro. Thein vivoefficacy of A‐251179 was characterized by suppression of spontaneous contractions in obstructed rat bladder and by measuring urodynamic function of urethane‐anesthetized rat models.

Key Results:

A‐251179 was about 4‐fold more selective in activating SUR2B‐Kir6.2 derived KATPchannels compared to those derived from SUR2A‐Kir6.2. In pig bladder smooth muscle strips, A‐251179 suppressed spontaneous contractions, about 27‐ and 71‐fold more potently compared to suppression of contractions evoked by low‐frequency electrical stimulation and carbachol, respectively.In vivo, A‐251179 suppressed spontaneous non‐voiding bladder contractions from partial outlet‐obstructed rats. Interestingly, in the neurogenic model where isovolumetric contractions were measured by continuous transvesical cystometry, A‐251179 at a dose of 0.3 μmol kg‐1, but not higher, was found to increase bladder capacity without affecting either the voiding efficiency or changes in mean arterial blood pressure.

Conclusions and Implications:

The thioureabenzamide analog, A‐251179 is a potent novel KATPchannel opener with selectivity for SUR2B/Kir6.2 containing KATPchannels relative to pinacidil. The pharmacological profile of A‐251179 is to increase bladder capacity and to prolong the time between voids without affecting voiding efficiency and represents an interesting characteristic to be explored for further investigations of KATPchannel openers for the treatment of overactive bladder.

British Journal of Pharmacology(2007)151, 467–475; doi:10.1038/sj.bjp.0707249
An Automated Approach for the Optimization of Pixel-Based Visualizations
Authors: Schneidewind Jörn , Sips Mike , Keim Daniel A.
Published: April 2007

During the last two decades, a wide variety of advanced methods for the visual exploration of large data sets have been proposed. For most of these techniques user interaction has become a crucial element, since there are many situations in which users or analysts have to select the right parameter settings from among many in order to construct insightful visualizations. The right choice of input parameters is essential, since suboptimal parameter settings or the investigation of irrelevant data dimensions make the exploration process more time consuming and may result in wrong conclusions. But finding the right parameters is often a tedious process and it becomes almost impossible for an analyst to find an optimal parameter setting manually because of the volume and complexity of today's data sets. Therefore, we propose a novel approach for automatically determining meaningful parameter- and attribute settings based on the combined analysis of the data space and the resulting visualizations with respect to a given task. Our technique automatically analyzes pixel images resulting from visualizations created from diverse parameter mappings and ranks them according to the potential value for the user. This allows a more effective and more efficient visual data analysis process, since the attribute/parameter space is reduced to meaningful selections and thus the analyst obtains faster insight into the data. Real-world applications are provided to show the benefit of the proposed approach.
Kinetics of stochastic degradation∕evaporation processes in nanoparticle aggregates and polymerlike systems with multiple bonds
Authors: Gramotnev D. K. , Gramotnev G.
Published: April 2007

Using the graph representation of stochastic degradation∕evaporation processes, general solutions of kinetic rate equations are found and analyzed, describing degradation of complex systems with multiple bonds, such as particle aggregates, fractals, self-arranged systems, double-stranded polymers and polymer networks, biological molecules, etc. The analysis is conducted on the example of thermal fragmentation of aerosol nanoparticles, caused by stochastic evaporation of bonding volatile molecules. A simple analytical approach for the determination of numbers of particles at different degradation stages, undertaking different evolutionary paths, is developed and applied for the analysis of several specific types of aerosol particle aggregates. Significant probabilistic delays are shown to occur during degradation∕fragmentation of intermediate modes, resulting in accumulation of particles in these modes. Conditions for such accumulation are determined and discussed. The obtained results are immediately applicable for the analysis of any other polymerlike systems with multiple bonds experiencing stochastic degradation.
First-principles investigation of 3d transition elements in L1 TiAl
Authors: Dang Hong-Li , Wang Chong-Yu , Yu Tao
Published: April 2007

The effect of 3d transition elements (such as V, Cr, Mn, Fe, Co, and Ni additions) on material properties in L10 TiAl has been studied using the first-principles DMol and discrete variational method within the framework of the density-functional theory. The transfer energy calculation indicates that all these 3d elements show a tendency to substitute for Al sites in the stoichiometric TiAl alloy, with the increasing order V<Cr<Mn<Ni<Fe<Co. Our results show that the local distortion of crystal lattice around an impurity atom is nonuniform, and it is found that the important influencing factors on the local lattice distortion are the impurity atom size and the site preference. Based on the effects of the doped alloying elements on the structural parameters and mechanical properties, we conclude that the larger bond strength and the smaller axial ratio benefit the ductility.
Screening effects on structure and diffusion in confined charged colloids
Authors: Kittner Madeleine , Klapp Sabine H. L.
Published: April 2007

Using molecular dynamics computer simulations we investigate structural and dynamic (diffusion) properties of charged colloidal suspension confined to narrow slit pores with structureless, uncharged walls. The system is modeled on an effective level involving only the macroions, which interact via a combination of a soft-sphere and a screened Coulomb potential. The aim of our study is to identify the role of the range of the macroion-macroion interaction controlled by the inverse Debye screening length, κ. We also compare to bulk properties at the same chemical potential as determined in parallel grand canonical Monte Carlo simulations. Our results reveal a significant influence of the interaction range which competes, however, with the influence of density. At liquidlike densities a decrease of range yields a decreasing mobility (and a corresponding enhancement of local structure) in the bulk system, whereas the reverse effect occurs in narrow slits with thickness of a few particle diameter. These differences can be traced back to the confinement-induced, and κ-dependent, reduction of overall density compared to the bulk reservoir. We also show that an increase of κ softens the oscillations in the normal pressure as function of the wall separation, which is consistent with experimental observations concerning the influence of addition of salt.
Hydrodynamic focusing in microstructures: Improved detection efficiencies in subfemtoliter probe volumes
Authors: de Mello Andrew J. , Edel Joshua B.
Published: April 2007

We present a method for improving detection efficiencies in single molecule confocal fluorescence spectroscopy with subfemtoliter probe volumes within microfluidic channels. Our approach is based on hydrodynamically focusing an analyte stream within a microfluidic channel down to a width on the same order of magnitude as that of the confocal probe volume. Experiments are performed in which fluorescently labeled polystyrene microspheres (930 nm diameter) are motivated through a microchannel and passed through a focused laser beam at a variety of flow rates (0.1−11 μL∕min). Hydrodynamic focusing of the analyte stream is achieved by introduction of two sheath flow streams that flank the central analyte stream. Through variation of the relative flow rates in each input stream the analyte stream can be controlled with micron resolution. A maximum hydrodynamic focusing width of 3 μm was achieved within a 50 μm wide microfluidic channel; hence, a larger proportion of molecules traveling through the microfluidic device were detected. Furthermore, simple statistical methods are used to investigate the resulting fluorescence bursts and generate single-particle burst width and burst area distributions. From these data, the total detection efficiencies are shown to be an order of magnitude better than those achievable in conventional unfocused systems.
Easily fabricated magnetic traps for single-cell applications
Authors: Koschwanez John H. , Carlson Robert H. , Meldrum Deirdre R.
Published: April 2007

We describe a simple and inexpensive method of fabricating single cell magnetic traps within a polydimethylsiloxane (PDMS) device. These traps were developed as part of an automated system that captures individual yeast cells in a microfluidic device and analyzes each cell as it buds. To make the traps, PdCl2 catalyst is rubbed with vinyl foam onto plasma-patterned PDMS, and then Co-Ni-B alloy is electrolessly deposited onto the catalyst at a moderate temperature. We demonstrate individual yeast cell capture and estimate the capture force (1.9−4.4 pN) by measuring the flow speed required to remove the cell from its trap in a microfluidic channel.
Direct and in vitro observation of growth hormone receptor molecules in A549 human lung epithelial cells by nanodiamond labeling
Authors: Cheng C.-Y. , Perevedentseva E. , Tu J.-S. , Chung P.-H. , Cheng C.-L. , Liu K.-K. , Chao J.-I. , Chen P.-H. , Chang C.-C.
Published: April 2007

This letter presents direct observation of growth hormone receptor in one single cancer cell using nanodiamond-growth hormone complex as a specific probe. The interaction of surface growth hormone receptor of A549 human lung epithelial cells with growth hormone was observed using nanodiamond’s unique spectroscopic signal via confocal Raman mapping. The growth hormone molecules were covalent conjugated to 100nm diameter carboxylated nanodiamonds, which can be recognized specifically by the growth hormone receptors of A549 cell. The Raman spectroscopic signal of diamond provides direct and in vitro observation of growth hormone receptors in physiology condition in a single cell level.
The First Aminimide Synthesis from Benzoyl Azide and Pyridine
Authors: Capuano Ben , Crosby Ian T. , Lloyd Edward J. , Neve Juliette E.
Published: April 2007

Irradiation of benzoyl azide 1 at 254 nm in the presence of some amines produces aminimides: in the presence of pyridine the aminimide 13 can be isolated in 41% yield; in the presence of N,N-dimethylaniline a CH insertion product 7 is obtained via an intermediate aminimide 12. This is the first reported synthesis of aminimides from a benzoyl azide.
Use of an ion-selective electrode for free copper measurements in low salinity and low ionic strength matrices
Authors: Rachou Julien , Gagnon Christian , Sauvé Sébastien
Published: April 2007

Environmental context. The toxicity of metals in the environment is controlled by several parameters including total metal concentration, pH and organic and inorganic ligands (type and concentration). The characterisation of different metal pools in natural matrices (e.g. seawater, soil) is important for the evaluation of their toxic impact. The copper ion-selective electrode (Cu-ISE) is a method of choice for the analytical determination of the speciation (i.e. chemical forms) of divalent copper in natural matrices. This paper clarifies several operational parameters in the hope of decreasing variability of results and increasing the application domain of the Cu-ISE.
Abstract. The determination of free copper concentrations in natural matrices is critical for the evaluation of copper toxicity. The ISE is one of the few analytical means for determining the direct speciation of free metal species. We have refined the method for low salinity and low ionic strength solutions for application with soil water extracts or fresh waters. Moreover, we have detailed and standardised a method for using a Cu-ISE with an autotitrator. The standardisation shows a good response and allows significant time saving (under 2 h for the calibration). The results obtained using the ISE are compared with those predicted in the presence of different organic ligands or even the lower free Cu2+ activities resulting from the formation of Cu hydroxyl species. The method was validated for the determination of Cu speciation at environmentally relevant free Cu2+ activity, i.e. ranging between 10−14 to 10−4 M. The chemical equilibrium calculations were made using the MINEQL+ software and the results agree well for pH values between 3 and 10. In terms of precision, the standard deviations of the measured values never exceed 0.1 units, and in terms of accuracy, the measured values were very close to the nominal values, within a range of 0.1. Outside the optimal pH range, the electrode yields higher activity than expected.
Fractionation of anthropogenic lead and zinc in Deûle River sediments
Authors: Boughriet A. , Recourt P. , Proix N. , Billon G. , Leermakers M. , Fischer J-C. , Ouddane B.
Published: April 2007

Environmental context. Metal contamination from smelting plants can have significant environmental and geochemical impacts on surrounding river systems, where large amounts of ores, dusts and slag are often discharged. Pollution levels in a river in northern France in the vicinity of a plant that had been producing zinc and lead have been measured. The authors assessed and identified the forms and phases of these metals in the polluted sediments, in order to assess the ability of these metals to pass into water when physicochemical changes (pH, redox potential) occur in the medium, for instance, as a result of dredging and barge traffic.
Abstract. The degradation of a fluvial environment, the Deûle River in northern France, with metals has been examined. Sites of environmentally significant sediment metal contamination were identified near a former smelting plant (Metaleurop) that produced lead and zinc. The chemical fractionation of sedimentary lead and zinc was carried out by using a four-stage sequential procedure in the polluted sediments. Chemical treatments were performed on these sediments with increasingly strong phase-specific reagents and under controlled thermal conditions; the recovered solutions were subsequently analysed using inductively coupled plasma–atomic emission spectroscopy (ICP-AES). The partitioning of lead and zinc in Deûle River sediment samples was further compared with those found in less contaminated sites upstream and downstream from the former Metaleurop factory. Analytical data showed the extent of industrial pollution in this sediment, particularly, the implication of: (i) anthropogenic lead and zinc on the easily extractable fraction; (ii) smelter inputs containing of sulfidic ores on the sulfide/organic fraction; and (iii) smelter dust, slags and possibly ores derived from oxides in the reducible fraction. Overall, in polluted water, sediment-bound lead and zinc were found to be associated with all the sedimentary phases (the average mass percentages of lead and zinc in the exchangeable ions/carbonate fraction were respectively: 12% and 23%; in Fe and Mn oxides and hydroxides: 48% and 35%; in sulfides and organics: 33% and 29%; and in clays and aluminosilicates: 7% and 14%). Using X-ray diffraction, heavy minerals that were previously separated from sediments by decantation with gravity were shown to consist mostly of galena (PbS), wurtzite (ZnS), and pyrite (FeS2), showing the importance of sulfides in this sedimentary material. Using environmental scanning electron microscopy with energy dispersive X-ray spectroscopy (ESEM/EDS), sediments were found to be highly heterogeneous assemblages or aggregates, but with some isolated crystals that were identified. Detailed ESEM/EDS analyses (with imaging) have enabled us to demonstrate the existence of numerous lead and zinc phases that agree well with X-ray diffraction results and sequential extraction data.
Chimaerin and Rac regulate cell number, adherens junctions, and ERK MAP kinase signaling in the
Drosophila
eye
Authors: Bruinsma Stephen P. , Cagan Ross L. , Baranski Thomas J.
Published: April 2007

The chimaerin family of Rac GTPase-activating proteins (GAPs) has been implicated in neural development and tumor progression, although the cellular mechanisms of their effects are poorly understood. To study their physiologic function, we used the
Drosophila
retina as a model system. Reduced expression of the fly chimaerin ortholog RhoGAP5a in the pupal eye led to an excess of interommatidial pigment cells, aberrant cell contacts, and an increase in activated ERK that localized specifically to the plasma membrane. Reducing RhoGAP5A levels suppressed the effects of disrupted EGF receptor signaling. Perturbation of Rac activity led to similar phenotypes, whereas coexpression of Rac and
RhoGAP5A-dsRNAi
resulted in the elimination of adherens junctions between interommatidial cells. Our results reveal a role for chimaerin in the regulation of ERK signaling and cell–cell adhesion and have implications for its participation in epithelial development and tumor progression.
Failures of Adenoidectomy for Chronic Rhinosinusitis in Children: For Whom and When Do They Fail?
Authors: Ramadan Hassan H. , Tiu Jeremy
Published: April 2007

Objectives: To determine which children who are treated with adenoidectomy for chronic rhinosinusitis (CRS) will ultimately undergo endoscopic sinus surgery (ESS) and the length of time between adenoidectomy and ESS.

Study Design: Retrospective chart review of prospectively collected data in a tertiary pediatric otolaryngology service.

Methods: One hundred forty‐three children had adenoidectomy for CRS over a 10‐year period. Follow‐up was available on 121 children. Sixty‐one children failed the procedure. Data were available on 55 children who underwent ESS after failing adenoidectomy for the treatment of CRS. Mean time from adenoidectomy to ESS was determined. Factors such as age, allergic rhinitis, asthma, computed tomography (CT) score, and sex were evaluated for effects on this time.

Results: With use of Cox regression analysis, the mean time from adenoidectomy to ESS was 24 months, ranging from 4 to 77 months. The presence of asthma (P < .04) and age less than 7 years (P < .01) were predictors of earlier failure. Allergic rhinitis (P < .3), CT score (P < .9), and sex (P < .3) showed no effect.

Conclusions: Those who fail adenoidectomy for CRS who require ESS are mainly children who are younger than 7 years of age and have asthma. They appear to require a salvage ESS at a mean of 24 months after the adenoidectomy.
SWI/SNF is required for transcriptional memory at the yeast GAL gene cluster
Authors: Kundu Sharmistha , Horn Peter J. , Peterson Craig L.
Published: April 2007

Post-translational modification of nucleosomal histones has been suggested to contribute to epigenetic transcriptional memory. We describe a case of transcriptional memory in yeast where the rate of transcriptional induction of GAL1 is regulated by the prior expression state. This epigenetic state is inherited by daughter cells, but does not require the histone acetyltransferase, Gcn5p, the histone ubiquitinylating enzyme, Rad6p, or the histone methylases, Dot1p, Set1p, or Set2p. In contrast, we show that the ATP-dependent chromatin remodeling enzyme, SWI/SNF, is essential for transcriptional memory at GAL1. Genetic studies indicate that SWI/SNF controls transcriptional memory by antagonizing ISWI-like chromatin remodeling enzymes.
Geographical variation and positive diversifying selection in the host‐specific toxin SnToxA
Authors: STUKENBROCK EVA H. , MCDONALD BRUCE A.
Published: April 2007

The host‐specific toxin ToxA produced by the wheat pathogens Pyrenophora tritici‐repentis and Phaeosphaeria nodorum interacts with the product of the dominant plant gene Tsn1 to induce necrosis. The ToxA gene is thought to have been acquired by Py. tritici‐repentis from Ph. nodorum through a recent horizontal gene transfer event. PCR and sequence analysis indicate that the level of ToxA variation, including gene deletion, in Ph. nodorum (SnToxA) is significantly higher than in Py. tritici‐repentis (PtrToxA). We PCR‐screened 788 isolates of Ph. nodorum originating from eight geographical regions to infer the pattern of SnToxA deletions. The frequency of deletions differed significantly among populations, ranging from 0% (Australia) to 98% (China). Sequence analysis of the SnToxA gene in 123 Ph. nodorum isolates revealed 13 distinct haplotypes. The distribution and diversity of haplotypes varied significantly among populations. The majority of SnToxA mutations were non‐synonymous resulting in changes at the protein level. We applied different models of selection to infer the mode of evolution operating at the ToxA locus. Evidence for positive diversifying selection supports the hypothesis that evolution of the ToxA locus is driven by selection imposed by the host. The distribution of SnToxA alleles and deletions may reflect the distribution of different Tsn1 alleles in the corresponding host populations.
Hospitalized children's mood differences during play and music therapy
Authors: Hendon C. , Bohon L. M.
Published: April 2007

Background  Paediatric hospitals are concerned with both the physical and social well‐being of their young patients. These institutions often provide play and music therapy to enhance the child's sense of normality. The purpose of this study was to test whether children in a hospital were happier during music rather than play therapy.

Methods  Sixty children were observed either during play or music therapy. Happiness was operationally defined as the frequency of smiles during a 3 minute period.

Results  The results showed that music therapy (M = 12.43, SD = 4.83) led to significantly more smiles than did play therapy (M = 5.83, SD = 3.10).

Conclusions  Increasing the amount of time hospitals provide music therapy for child patients may be a way to increase positive effect and ultimately to increase mental and physical well‐being in hospitalized children.