bluuebunny/crossref_metadata_2025 huggingface dataset:
Knee Joint Secondary Motion Accuracy Improved by Quaternion-Based Optimizer With Bony Landmark Constraints
Authors: Wang Hongsheng , Zheng Naiqaun (Nigel)
Published: October 2010

Skin marker-based motion analysis has been widely used in biomechanical studies and clinical applications. Unfortunately, the accuracy of knee joint secondary motions is largely limited by the nonrigidity nature of human body segments. Numerous studies have investigated the characteristics of soft tissue movement. Utilizing these characteristics, we may improve the accuracy of knee joint motion measurement. An optimizer was developed by incorporating the soft tissue movement patterns at special bony landmarks into constraint functions. Bony landmark constraints were assigned to the skin markers at femur epicondyles, tibial plateau edges, and tibial tuberosity in a motion analysis algorithm by limiting their allowed position space relative to the underlying bone. The rotation matrix was represented by quaternion, and the constrained optimization problem was solved by Fletcher’s version of the Levenberg–Marquardt optimization technique. The algorithm was validated by using motion data from both skin-based markers and bone-mounted markers attached to fresh cadavers. By comparing the results with the ground truth bone motion generated from the bone-mounted markers, the new algorithm had a significantly higher accuracy (root-mean-square (RMS) error: 0.7±0.1 deg in axial rotation and 0.4±0.1 deg in varus-valgus) in estimating the knee joint secondary rotations than algorithms without bony landmark constraints (RMS error: 1.7±0.4 deg in axial rotation and 0.7±0.1 deg in varus-valgus). Also, it predicts a more accurate medial-lateral translation (RMS error: 0.4±0.1 mm) than the conventional techniques (RMS error: 1.2±0.2 mm). The new algorithm, using bony landmark constrains, estimates more accurate secondary rotations and medial-lateral translation of the underlying bone.
Impact of the gas-surface scattering and gas molecule-molecule interaction on the mass flow rate of the rarefied gas through a short channel into a vacuum
Authors: Sazhin O.
Published: October 2010

The rarefied gas flow through a short channel into a vacuum has been investigated computationally using the direct simulation Monte Carlo method. Taking into account the gas-surface scattering and the gas molecule-molecule interaction, the mass flow rate is calculated as a function of gas rarefaction and the length to height ratio. This study demonstrates that the effects of the gas molecule-molecule interaction and the gas-surface scattering can make a noticeable impact on the mass flow rate of the rarefied gas through a short channel into a vacuum. The maximum manifestation of these effects was evaluated.
Scenarios for Global Biodiversity in the 21st Century
Authors: Pereira Henrique M. , Leadley Paul W. , Proença Vânia , Alkemade Rob , Scharlemann Jörn P. W. , Fernandez-Manjarrés Juan F. , Araújo Miguel B. , Balvanera Patricia , Biggs Reinette , Cheung William W. L. , Chini Louise , Cooper H. David , Gilman Eric L. , Guénette Sylvie , Hurtt George C. , Huntington Henry P. , Mace Georgina M. , Oberdorff Thierry , Revenga Carmen , Rodrigues Patrícia , Scholes Robert J. , Sumaila Ussif Rashid , Walpole Matt
Published: October 2010

Assessing Biodiversity Declines

Understanding human impact on biodiversity depends on sound quantitative projection.

Pereira
et al.

(p.
1496
, published online 26 October) review quantitative scenarios that have been developed for four main areas of concern: species extinctions, species abundances and community structure, habitat loss and degradation, and shifts in the distribution of species and biomes. Declines in biodiversity are projected for the whole of the 21st century in all scenarios, but with a wide range of variation.

Hoffmann
et al.

(p.
1503
, published online 26 October) draw on the results of five decades' worth of data collection, managed by the International Union for Conservation of Nature Species Survival Commission. A comprehensive synthesis of the conservation status of the world's vertebrates, based on an analysis of 25,780 species (approximately half of total vertebrate diversity), is presented: Approximately 20% of all vertebrate species are at risk of extinction in the wild, and 11% of threatened birds and 17% of threatened mammals have moved closer to extinction over time. Despite these trends, overall declines would have been significantly worse in the absence of conservation actions.
Molecular Investigation of Resistance to the Antituberculous Drug Ethionamide in Multidrug-Resistant Clinical Isolates of
Mycobacterium tuberculosis
Authors: Brossier F. , Veziris N. , Truffot-Pernot C. , Jarlier V. , Sougakoff W.
Published: October 2010

Ethionamide (ETH) needs to be activated by the mono-oxygenase EthA, which is regulated by EthR, in order to be active against
Mycobacterium tuberculosis
. The activated drug targets the enzyme InhA, which is involved in cell wall biosynthesis. Resistance to ETH has been reported to result from various mechanisms, including mutations altering EthA/EthR, InhA and its promoter, the NADH dehydrogenase encoded by
ndh
, and the MshA enzyme, involved in mycothiol biosynthesis. We searched for such mutations in 87 clinical isolates: 47 ETH-resistant (ETH
r
) isolates, 24 ETH-susceptible (ETH
s
) isolates, and 16 isolates susceptible to ETH but displaying an intermediate proportion of resistant cells (ETH
Sip
; defined as ≥1% but <10% resistant cells). In 81% (38/47) of the ETH
r
isolates, we found mutations in
ethA
,
ethR
, or
inhA
or its promoter, which mostly corresponded to new alterations in
ethA
and
ethR
. The 9 ETH
r
isolates without a mutation in these three genes (9/47, 19%) had no mutation in
ndh
, and a single isolate had a mutation in
mshA
. Of the 16 ETH
Sip
isolates, 7 had a mutation in
ethA
, 8 had no detectable mutation, and 1 had a mutation in
mshA
. Finally, of the 24 ETH
s
isolates, 23 had no mutation in the studied genes and 1 displayed a yet unknown mutation in the
inhA
promoter. Globally, the mechanism of resistance to ETH remained unknown for 19% of the ETH
r
isolates, highlighting the complexity of the mechanisms of ETH resistance in
M. tuberculosis
.
Mucosal Immunization of Rhesus Monkeys against Respiratory Syncytial Virus Subgroups A and B and Human Parainfluenza Virus Type 3 by Using a Live cDNA-Derived Vaccine Based on a Host Range-Attenuated Bovine Parainfluenza Virus Type 3 Vector Backbone
Authors: Schmidt Alexander C. , Wenzke Daniel R. , McAuliffe Josephine M. , St. Claire Marisa , Elkins William R. , Murphy Brian R. , Collins Peter L.
Published: October 2010

Reverse genetics was used to develop a two-component, trivalent live attenuated vaccine against human parainfluenza virus type 3 (HPIV3) and respiratory syncytial virus (RSV) subgroups A and B. The backbone for each of the two components of this vaccine was the attenuated recombinant bovine/human PIV3 (rB/HPIV3), a recombinant BPIV3 in which the bovine HN and F protective antigens are replaced by their HPIV3 counterparts (48). This chimera retains the well-characterized host range attenuation phenotype of BPIV3, which appears to be appropriate for immunization of young infants. The open reading frames (ORFs) for the G and F major protective antigens of RSV subgroup A and B were each placed under the control of PIV3 transcription signals and inserted individually or in homologous pairs as supernumerary genes in the promoter proximal position of rB/HPIV3. The level of replication of rB/HPIV3-RSV chimeric viruses in the respiratory tract of rhesus monkeys was similar to that of their parent virus rB/HPIV3, and each of the chimeras induced a robust immune response to both RSV and HPIV3. RSV-neutralizing antibody titers induced by rB/HPIV3-RSV chimeric viruses were equivalent to those induced by infection with wild-type RSV, and HPIV3-specific antibody responses were similar to, or slightly less than, after infection with the rB/HPIV3 vector itself. This study describes a novel vaccine strategy against RSV in which vaccine viruses with a common attenuated backbone, specifically rB/HPIV3 derivatives expressing the G and/or F major protective antigens of RSV subgroup A and of RSV subgroup B, are used to immunize by the intranasal route against RSV and HPIV3, which are the first and second most important viral agents of pediatric respiratory tract disease worldwide.
Artificial Extension of the Adenovirus Fiber Shaft Inhibits Infectivity in Coxsackievirus and Adenovirus Receptor-Positive Cell Lines
Authors: Seki Toshiro , Dmitriev Igor , Kashentseva Elena , Takayama Koichi , Rots Marianne , Suzuki Kaori , Curiel David T.
Published: October 2010

Recent studies demonstrate that virus-cellular receptor interactions are not the sole determinants of adenovirus (Ad) tropism. It has been shown that the fiber shaft length, which ranges from 6 to 23 β-repeats in human Ads, also influences viral tropism. However, there is no report that investigates whether artificial extension of the shaft alters the infectivity profile of Ad. Therefore, we constructed Ad serotype 5 (Ad5) capsid-based longer-shafted Ad vectors by incorporating Ad2 shaft fragments of different lengths into the Ad5 shaft. We show that “longer-shafted” Ad vectors (up to 32 β-repeats) could be rescued. We also show that longer-shafted Ad vectors had no impact on knob-CAR (coxsackievirus and Ad receptor) interaction compared to wild-type Ad. Nevertheless, gene transfer efficiencies of longer-shafted Ad vectors were lower in CAR-positive cell lines compared to wild-type Ad. We suggest that artificial extension of the shaft can inhibit infectivity in the context of CAR-positive cell lines without modification of knob-CAR interaction.
Molecular Dissection of the Semliki Forest Virus Homotrimer Reveals Two Functionally Distinct Regions of the Fusion Protein
Authors: Gibbons Don L. , Kielian Margaret
Published: October 2010

Semliki Forest virus (SFV) is an enveloped alphavirus that infects cells via a membrane fusion reaction triggered by the acidic pH of endosomes. In response to low pH, the E1 proteins on the virus membrane undergo a series of conformational changes, resulting in the formation of a stable E1 homotrimer. Little is known about the structural basis of either the E1 conformational changes or the resulting homotrimer or about the mechanism of action of the homotrimer in fusion. Here, the E1 homotrimer was formed in vitro from either virus or soluble E1 ectodomain and then probed by various perturbants, proteases, or glycosidase. The preformed homotrimer was extremely stable to moderately harsh conditions and proteases. By contrast, mild reducing conditions selectively disrupted the N-terminal region of trimeric E1, making it accessible to proteolytic cleavage and producing E1 fragments that retained trimer interactions. Trypsin digestion produced a fragment missing a portion of the N terminus just proximal to the putative fusion peptide. Digestion with elastase produced several fragments with cleavage sites between residues 78 and 102, resulting in the loss of the putative fusion peptide and the release of membrane-bound E1 ectodomain as a soluble trimer. Elastase also cleaved the homotrimer within an E1 loop located near the fusion peptide in the native E1 structure. Mass spectrometry was used to map the C termini of several differentially produced and fully functional E1 ectodomains. Together, our data identify two separate regions of the SFV E1 ectodomain, one responsible for target membrane association and one necessary for trimer interactions.
The Rat Cytomegalovirus R33-Encoded G Protein-Coupled Receptor Signals in a Constitutive Fashion
Authors: Gruijthuijsen Yvonne K. , Casarosa Paola , Kaptein Suzanne J. F. , Broers Jos L. V. , Leurs Rob , Bruggeman Cathrien A. , Smit Martine J. , Vink Cornelis
Published: October 2010

The rat cytomegalovirus (RCMV) R33 gene is conserved among all betaherpesviruses and encodes a protein (pR33) that shows sequence similarity with chemokine-binding G protein-coupled receptors (GPCRs). Previously, the physiological significance of the R33 gene was demonstrated by the finding that an RCMV strain with R33 deleted is severely attenuated in vivo and is unable to either enter or replicate in the salivary glands of infected rats. Here, we report that RCMV pR33 is expressed as a functional GPCR that signals in an agonist-independent manner in both COS-7 and Rat2 cells. Transient expression of pR33 in COS-7 cells results in constitutive activation of phospholipase C (PLC) due to coupling to G proteins of the G
q
class. Interestingly, PLC activation is partially inhibited by cotransfection with G
α
-transducin subunits, which indicates the involvement of G
βγ
as well as Gα subunits in pR33-mediated signaling. Surprisingly, PLC activation is also partially inhibited by addition of pertussis toxin (PTX), suggesting that pR33 activates not only G
q
but also G
i/0
proteins. The constitutive activation of G
i/0
proteins by pR33 is further demonstrated by the PTX-sensitive decrease of CRE-mediated transcription and the PTX-sensitive increase of both NF-κB- and SRE-mediated transcription. In contrast to its homolog of human herpesvirus 6B (pU12), pR33 does not bind RANTES.
A Potent Human Immunodeficiency Virus Type 1 Protease Inhibitor, UIC-94003 (TMC-126), and Selection of a Novel (A28S) Mutation in the Protease Active Site
Authors: Yoshimura Kazuhisa , Kato Ryohei , Kavlick Mark F. , Nguyen Aline , Maroun Victor , Maeda Kenji , Hussain Khaja A. , Ghosh Arun K. , Gulnik Sergei V. , Erickson John W. , Mitsuya Hiroaki
Published: October 2010

We identified UIC-94003, a nonpeptidic human immunodeficiency virus (HIV) protease inhibitor (PI), containing 3(
R
),3a(
S
),6a(
R
)-
bis
-tetrahydrofuranyl urethane (
bis
-THF) and a sulfonamide isostere, which is extremely potent against a wide spectrum of HIV (50% inhibitory concentration, 0.0003 to 0.0005 μM). UIC-94003 was also potent against multi-PI-resistant HIV-1 strains isolated from patients who had no response to any existing antiviral regimens after having received a variety of antiviral agents (50% inhibitory concentration, 0.0005 to 0.0055 μM). Upon selection of HIV-1 in the presence of UIC-94003, mutants carrying a novel active-site mutation, A28S, in the presence of L10F, M46I, I50V, A71V, and N88D appeared. Modeling analysis revealed that the close contact of UIC-94003 with the main chains of the protease active-site amino acids (Asp29 and Asp30) differed from that of other PIs and may be important for its potency and wide-spectrum activity against a variety of drug-resistant HIV-1 variants. Thus, introduction of inhibitor interactions with the main chains of key amino acids and seeking a unique inhibitor-enzyme contact profile should provide a framework for developing novel PIs for treating patients harboring multi-PI-resistant HIV-1.
Altered Substrate Specificity of Drug-Resistant Human Immunodeficiency Virus Type 1 Protease
Authors: Dauber Deborah S. , Ziermann Rainer , Parkin Neil , Maly Dustin J. , Mahrus Sami , Harris Jennifer L. , Ellman Jon A. , Petropoulos Christos , Craik Charles S.
Published: October 2010

Resistance to human immunodeficiency virus type 1 protease (HIV PR) inhibitors results primarily from the selection of multiple mutations in the protease region. Because many of these mutations are selected for the ability to decrease inhibitor binding in the active site, they also affect substrate binding and potentially substrate specificity. This work investigates the substrate specificity of a panel of clinically derived protease inhibitor-resistant HIV PR variants. To compare protease specificity, we have used positional-scanning, synthetic combinatorial peptide libraries as well as a select number of individual substrates. The subsite preferences of wild-type HIV PR determined by using the substrate libraries are consistent with prior reports, validating the use of these libraries to compare specificity among a panel of HIV PR variants. Five out of seven protease variants demonstrated subtle differences in specificity that may have significant impacts on their abilities to function in viral maturation. Of these, four variants demonstrated up to fourfold changes in the preference for valine relative to alanine at position P2 when tested on individual peptide substrates. This change correlated with a common mutation in the viral NC/p1 cleavage site. These mutations may represent a mechanism by which severely compromised, drug-resistant viral strains can increase fitness levels. Understanding the altered substrate specificity of drug-resistant HIV PR should be valuable in the design of future generations of protease inhibitors as well as in elucidating the molecular basis of regulation of proteolysis in HIV.
Molecular Chaperone Hsp90 Is Important for Vaccinia Virus Growth in Cells
Authors: Hung Jan-Jong , Chung Che-Sheng , Chang Wen
Published: October 2010

Molecular chaperones assist protein folding, and some chaperones are induced by heat, nutrient depletion, or pathogen invasion. This study investigates the role played by Hsp90 in the life cycle of vaccinia virus. The titer of vaccinia intracellular mature virions (IMV) was reduced by 2 orders of magnitude in RK13 cells treated with geldanamycin (GA), which blocks the ATPase activity of Hsp90. GA does not affect expression from the viral early promoter, but treatment with GA delays DNA replication and intermediate gene transcription and reduces expression from the viral late promoter. Vaccinia virus infection does not induce Hsp90 expression; however, intracellular distribution of Hsp90 is altered in virus-infected cells. Hsp90 is restricted to the cytoplasm of mock-infected cells; in contrast, Hsp90 is transiently associated with virosomes in virus-infected cells although it is not incorporated into IMV. In addition, Hsp90 interacts with viral core protein 4a, the mature form of the A10L gene product, in virus-infected cells. In conclusion, these results suggest that a cellular chaperone protein, Hsp90, is important for vaccinia virus growth in cultured cells and that viral core protein 4a associates with Hsp90-containing complexes in the infected cells.
Soluble Receptor Potentiates Receptor-Independent Infection by Murine Coronavirus
Authors: Taguchi Fumihiro , Matsuyama Shutoku
Published: October 2010

Mouse hepatitis virus (MHV) infection spreads from MHV-infected DBT cells, which express the MHV receptor CEACAM1 (MHVR), to BHK cells, which are devoid of the receptor, by intercellular membrane fusion (MHVR-independent fusion). This mode of infection is a property of wild-type (wt) JHMV cl-2 virus but is not seen in cultures infected with the mutant virus JHMV srr7. In this study, we show that soluble MHVR (soMHVR) potentiates MHVR-independent fusion in JHMV srr7-infected cultures. Thus, in the presence of soMHVR, JHMV srr7-infected DBT cells overlaid onto BHK cells induce BHK cell syncytia and the spread of JHMV srr7 infection. This does not occur in the absence of soMHVR. soMHVR also enhanced wt virus MHVR-independent fusion. These effects were dependent on the concentration of soMHVR in the culture and were specifically blocked by the anti-MHVR monoclonal antibody CC1. Together with these observations, direct binding of soMHVR to the virus spike (S) glycoprotein as revealed by coimmunoprecipitation demonstrated that the effect is mediated by the binding of soMHVR to the S protein. Furthermore, fusion of BHK cells expressing the JHMV srr7 S protein was also induced by soMHVR. These results indicated that the binding of soMHVR to the S protein expressed on the DBT cell surface potentiates the fusion of MHV-infected DBT cells with nonpermissive BHK cells. We conclude that the binding of soMHVR to the S protein converts the S protein to a fusion-active form competent to mediate cell-cell fusion, in a fashion similar to the fusion of virus and cell membranes.
Unique Signatures of Long Noncoding RNA Expression in Response to Virus Infection and Altered Innate Immune Signaling
Authors: Peng Xinxia , Gralinski Lisa , Armour Christopher D. , Ferris Martin T. , Thomas Matthew J. , Proll Sean , Bradel-Tretheway Birgit G. , Korth Marcus J. , Castle John C. , Biery Matthew C. , Bouzek Heather K. , Haynor David R. , Frieman Matthew B. , Heise Mark , Raymond Christopher K. , Baric Ralph S. , Katze Michael G.
Published: October 2010

Studies of the host response to virus infection typically focus on protein-coding genes. However, non-protein-coding RNAs (ncRNAs) are transcribed in mammalian cells, and the roles of many of these ncRNAs remain enigmas. Using next-generation sequencing, we performed a whole-transcriptome analysis of the host response to severe acute respiratory syndrome coronavirus (SARS-CoV) infection across four founder mouse strains of the Collaborative Cross. We observed differential expression of approximately 500 annotated, long ncRNAs and 1,000 nonannotated genomic regions during infection. Moreover, studies of a subset of these ncRNAs and genomic regions showed the following. (i) Most were similarly regulated in response to influenza virus infection. (ii) They had distinctive kinetic expression profiles in type I interferon receptor and STAT1 knockout mice during SARS-CoV infection, including unique signatures of ncRNA expression associated with lethal infection. (iii) Over 40% were similarly regulated
in vitro
in response to both influenza virus infection and interferon treatment. These findings represent the first discovery of the widespread differential expression of long ncRNAs in response to virus infection and suggest that ncRNAs are involved in regulating the host response, including innate immunity. At the same time, virus infection models provide a unique platform for studying the biology and regulation of ncRNAs.

IMPORTANCE
Most studies examining the host transcriptional response to infection focus only on protein-coding genes. However, there is growing evidence that thousands of non-protein-coding RNAs (ncRNAs) are transcribed from mammalian genomes. While most attention to the involvement of ncRNAs in virus-host interactions has been on small ncRNAs such as microRNAs, it is becoming apparent that many long ncRNAs (>200 nucleotides [nt]) are also biologically important. These long ncRNAs have been found to have widespread functionality, including chromatin modification and transcriptional regulation and serving as the precursors of small RNAs. With the advent of next-generation sequencing technologies, whole-transcriptome analysis of the host response, including long ncRNAs, is now possible. Using this approach, we demonstrated that virus infection alters the expression of numerous long ncRNAs, suggesting that these RNAs may be a new class of regulatory molecules that play a role in determining the outcome of infection.
A Toll-Like Receptor-Responsive Kinase, Protein Kinase R, Is Inactivated in Endotoxin Tolerance through Differential K63/K48 Ubiquitination
Authors: Perkins Darren J. , Qureshi Nilofer , Vogel Stefanie N.
Published: October 2010

Overwhelming inflammation triggered by systemic infection in bacterial sepsis contributes to the pathology of this condition. Toll-like receptors (TLRs) are important in early septic inflammation. As a safeguard, the innate immune system has evolved to counter excessive inflammation through the induction of “tolerance.” In endotoxin tolerance, TLR signaling is inhibited and/or attenuated by multiple mechanisms that mitigate the ability of lipopolysaccharide (LPS) to activate critical kinases through TLR4. Here, we describe a novel mechanism. Protein kinase R (PKR), a kinase normally activated by a subset of TLRs, is rendered unresponsive to LPS in endotoxin-tolerized cells. In its naive state, PKR is subject to K63-linked ubiquitination (Ub), followed by K48-linked Ub, in response to LPS. In tolerance, the kinetics of this differential Ub is altered, resulting in a predominance of K48-linked chains, concomitant with a loss of PKR activation. These findings provide a novel mechanism by which a TLR-responsive kinase may be rendered inactive in tolerance.

IMPORTANCE“Endotoxin tolerance” is a period of transient unresponsiveness to the lipopolysaccharide (LPS) outer membrane component of Gram-negative bacteria that is induced by prior exposure to LPS through Toll-like receptor 4 (TLR4). The loss of LPS-inducible cytokine production by macrophages from patients who have experienced Gram-negative sepsis is well documented, and the increased susceptibility of such patients to reinfection has been attributed to the development of endotoxin tolerance. Multiple mechanisms have been proffered to account for this attenuated response. Using the LPS-responsive kinase protein kinase R (PKR), we have identified differential K48 versus K63 ubiquitination as an additional molecular mechanism by which signal-transducing elements may be inactivated in a state of endotoxin tolerance. This work is highly significant because it links recent discoveries concerning the important role of ubiquitination of signaling molecules in regulating TLR signaling with the loss of LPS responsiveness in tolerance.
Morphological Abnormalities in Chironomidae (Diptera) Larvae as Measures of Toxic Stress in Freshwater Ecosystems: Indexing Antennal Deformities in Chironomus Meigen
Authors: Warwick W. F.
Published: October 2010

An indexing scheme for classifying antennal deformations in the genus Chironomus is presented to illustrate the potential for using deformities in chironomid larvae as a biological screening technique for the detection and assessment of contaminants in aquatic ecosystems. The scheme utilizes six basic steps to determine an index of morphological response (IMR) for each individual larvae; these steps evaluate (1) the loss of genuine segments and/or the presence of questionable segments, (2) the reduction in length of the antenna, (3) the displacement or loss of the ring organ, (4) the fusion of the apex of the basal segment, (5) the displacement of accessory organs, and (6) the presence of structures of unknown homology. The values for IMR are summed and divided by the total number of larvae examined to calculate an index of severity of antennal deformation (ISAD) for the sample population. Comparison of the incidence (percent) and severity of antennal deformations (ISAD) in Chironomus populations from Tobin Lake (contaminated) and Last Mountain Lake (comparatively uncontaminated) ecosystems in south-central Saskatchewan show that both indices are higher in Tobin Lake. Improved mounting procedures are presented in which specimens are fully flattened to improve visibility of fine detail and enhance analytical consistency. Some results from preliminary dose–response experiments using 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) are presented. These results suggest that larval antennae are very sensitive to low-level, chronic exposure to toxic chemicals. New receptor organs are also described which make the morphology of the antennae of Chironomini and Tanytarsini directly comparable.
Effects of Manipulations of Aluminum Concentrations and pH on Phosphate Uptake and Photosynthesis of Planktonic Communities in Two Precambrian Shield Lakes
Authors: Nalewajko C. , Paul B.
Published: October 2010

From June 1982 to October 1983 we studied the physiological responses of phytoplankton to aluminum perturbations in a circumneutral lake (St. Nora Lake) and an acid-stressed lake (Plastic Lake) on the Precambrian Shield in Ontario. In both lakes, addition of aluminum to water samples decreased microbial phosphate uptake and photosynthesis; significant decreases occurred at 50 μg Al∙L−1. Both processes were affected more at pH 5.2–6.9 than at pH 4.5, phosphate uptake was depressed relatively more than photosynthesis, and depression of both processes was larger in Plastic Lake than in St. Nora Lake. Precipitation of phosphate as particles > 0.45 μm upon addition of aluminum, as well as direct toxicity of aluminum, appear to be responsible for the observed detrimental effects of aluminum.
Fertilization and Egg Retention in Artificially Inseminated Female American Lobsters, Homarus americanus
Authors: Waddy S. L. , Aiken D. E.
Published: October 2010

Female American lobsters, Homarus americanus, seldom are receptive to mating more than 24 h after they molt, a fact that complicates breeding programs in large facilities where animals are held individually. Artificial insemination can eliminate this problem, but preliminary studies have indicated poor fertilization success from intermolt inseminations. In the present study, 86 female American lobsters of wild and cultured stock were artificially inseminated in all postmolt and intermolt stages, 64 subsequently spawned, and 98% successfully fertilized their eggs, indicating no constraint of molt stage on success of insemination. Of artificially inseminated females, 50% of wild stock and 7% of cultured stock carried their eggs to hatch.
Influence of Snowcover Development and Ground Freezing on Cation Loss from a Wetland Watershed during Spring Runoff
Authors: Pierson D. C. , Taylor C. H.
Published: October 2010

Cation and water export were monitored from a small wetland watershed in south-central Ontario during spring runoff for two years with very different sequences of snowpack development. In 1977, a persistent snow cover developed in the watershed by 1 December, and snow accumulation was near normal for this region. In 1980, persistent snow cover did not develop until mid-January, and the final snowpack was well below average. Between years, major differences in the timing of ion export were found for calcium, magnesium, and sodium, ions which appear to be associated with the watershed's soils. Conversely, potassium, a cation not as strongly associated with soil ion sources, showed temporal patterns of export which were similar in timing during the two years. We hypothesize that concrete soil frost, which developed in 1980 as a consequence of the late-developing snow cover, strongly influenced the timing of ion export by isolating early spring runoff from the watershed's soils. Streamwater hydrogen ion concentrations decreased rapidly during the first week of spring runoff in 1980, indicating that hydrogen ion export was increased by a similar mechanism. We suggest that in poorly buffered systems, the formation of concrete soil frost may lead to significant increases in hydrogen ion export during spring snowmelt.
Potential Usefulness of Chlorine for Controlling Pacific Salmon Leeches, Piscicola salmositica, in Hatcheries
Authors: Bower S. M. , Margolis L. , MacKay R. J.
Published: October 2010

Susceptibility to the lethal effects of low levels of total residual chlorine (TRC) differed between juvenile coho salmon (Oncorhynchus kisutch) and the salmon leech (Piscicola salmositica), the vector for the haemoflagellate salmonid pathogen Cryptobia salmositica. There was no salmon mortality at concentrations below approximately 50 μg TRC/L for the maximum exposure time of 24 h. Some damage to gill tissue (hypertrophy, fusion, oedema, and some necrosis), was observed at the highest concentrations of TRC that did not kill any of the fish (approximately 50 μg/L for 24 h, and approximately 100 μg/L for 8 h). This damage was repaired by the fish within 4 d of exposure, although evidence of past irritation was noted in 6 of 12 fish. All small juvenile leeches exposed to 44 μg TRC/L for 24 h died, and over half of such leeches exposed to 44 μg/L for 8 h and 21 μg/L for 24 h died. Below TRC concentrations that were lethal to the fish (approximately 50 μg/L), contours of constant leech mortality derived from a logistic regression model fitted to the data offered a wide range of concentrations and exposure times that would result in high mortality of juvenile leeches. Larger subadult and adult leeches were more resistant to chlorine than the smaller leeches but were more sensitive than the juvenile fish. Thus, chlorine may prove useful for controlling P. salmositica in salmonid hatcheries.
Acidification and Toxicity of Metals to Aquatic Biota
Authors: Campbel P. G. C. , Stokes P. M.
Published: October 2010

Acidification of freshwaters can in principle influence metal–organism interactions in at least two ways: the decrease in pH may affect metal speciation in solution, or it may affect biological sensitivity at the level of the cell surface. We considered the possible effects of environmental acidification (pH 7–4) on (1) metal speciation in solution, (2) metal adsorption at biological surfaces, and (3) metal uptake by and toxicity to aquatic biota. Attention was focused on some 10 metals of potential concern in the context of freshwater acidification (Ag, Al, Cd, Co, Cu, Hg, Mn, Ni, Pb, Zn). For the four metals (Al, Cu, Hg, Pb) predicted to manifest speciation changes in the range pH 7–4, confirmatory experimental data are available for two (Cu, Pb). In the six remaining cases predicted to show little sensitivity to pH changes in this range, supporting experimental evidence exists for four metals (Ag, Cd, Mn, Zn). A pH-dependent biological response is documented over a realistic range of H+ and metal concentrations for 6 of the 10 metals considered (Al, Cd, Cu, Zn, and to a lesser extent, Hg and Pb). These six metals fall into two groups: those for which a decrease in pH results in a decreased biological response (type I behavior: Cd, Cu, Zn) and those for which the dominant effect of acidification is to increase metal availability (type II behavior: Pb). Data for the remaining two metals (Al, Hg) clearly reveal pH effects, but the results are too few and too inconsistent to allow generalizations.
Detection of interstellar 13CCH and C13CH
Authors: Saleck A. H. , Simon R. , Winnewisser G. , Wouterloot J. G. A.
Published: October 2010

We report an unambiguous detection of the 13CCH and C13CH isotopomers of the ethynyl radical towards the Orion A ridge by identification of their N = 2 → 1 transitions. The observations have been made with the IRAM 30 m telescope at Pico Veleta, Spain. By these measurements, we confirm an earlier tentative detection of four hyperfine components of C13CH with the KOSMA 3 m telescope at Gornergrat, Switzerland. Although uncertainties in the calibration of line intensities are not completely settled, these observations suggest that C13CH might be the more abundant of the two 13C isotopomers. This tentative finding pertains towards the region where the emission of molecular radicals peaks, i.e., northeast of the Kleinmann–Low nebula. Furthermore, the N = 1 → 0 transition of C13CH has been detected in the same region with the SEST 15 m telescope at La Silla, Chile. In combination with the laboratory N = 4 ← 3 and N = 5 ← 4 data, we derive improved ground state rotational constants for both species.
Clustering across concentration gradients
Authors: Carlow G. R. , Zinke-Allmang M.
Published: October 2010

Clustering experiments on surfaces are of fundamental interest to verify theoretical concepts for phase-separation processes such as statistical self-similarity and scaling behaviour. Unfortunately, often the differences between theoretical models are too small to be studied with standard sample preparation techniques, as experimental uncertainties result in variations in the results of the same order of magnitude as the effects that we want to study. In this paper we study a modified approach where two different initial morphologies are prepared on the same surface so that the dynamic processes occur in parallel under identical conditions. From observations of clustering near the concentration step we find that the material transfer during late stage ripening is limited to within a distance that is less than the diffusion length. This result is in agreement with a theoretical model that predicts that the interface is confined to a width of the order of the cluster–cluster distance. The two sides beyond this length evolve independently.
Theoretical search for the Rydberg dimer of H3
Authors: Wright James S.
Published: October 2010

The lowest lying bound electronic state of H3 has the equilateral triangular H3+ core, with an outer electron in the 2s Rydberg orbital. Electronic transitions to this [Formula: see text] state were first observed by Herzberg and co-workers. Combining two such Rydberg monomers into a spin-paired Rydberg dimer may lead to significant stabilization at a long geometry where the 2s orbitals overlap. This paper includes the search for such an electronic state, as well as discussion of other electronic states that are unbound. Although the dimer state is not the lowest lying electronic state, it does show a substantial potential energy minimum at a ring–ring distance of 6.75 bohr. The D3h symmetry for the Rydberg state is broken by a small distortion that leads to an isoceles triangle.
Broadening and shifting of the Raman Q branch in D2 and D2–He mixtures, II: line shapes, fitting routines, and effects nonlinear in density
Authors: Sinclair P. M. , Duggan P. , Forsman J. W. , Drummond J. R. , May A. D.
Published: October 2010

In the preceding paper we fitted the experimental profiles using a single Lorentzian line shape and assumed that the width and shift were proportional to the density. Here we discuss nonlinear contributions to widths and shifts and present a different spectral profile and analysis that allows us (i) to determine unbiased, binary collision, impact limit, broadening and shifting coefficients; (ii) to disentangle several effects nonlinear in the density; and, subsequently, (iii) to observe broadening and shifting arising purely from the correlation between perturbers and three-body interactions. This is a new avenue of research in molecular dynamics. In addition, measurements of the broadening of the depolarized part of the Q branch in D2 are reported for the first time.
Extreme UV absorption spectroscopy of CO isotopomers in pulsed supersonic free jet expansions
Authors: Rostas F. , Launay F. , Eidelsberg M. , Benharrous M. , Blaess C. , Huber K. P.
Published: October 2010

A supersonic pulsed jet for high-resolution studies of rotationally cold molecules was constructed at the 10.6 m vacuum UV spectrograph of the Observatoire de Meudon. The background continuum for photographic absorption work is emitted from a pulsedBalloffet–Romand–Vodar (BRV) source (vacuum spark). The new apparatus has been used to record the absorption spectra of the four main isotopomers of CO from 880 to 1110 Å (1 Å = 10−10 m). First results of the analysis help to clarify the rovibronic structure in two specific regions of the spectrum (103 000–103 300 and 109 300–109 600 cm−1) and are relevant to the discussion of 1Σ+–1Σ+ and 1Π–1Π homogeneous interactions of CO.
Vibrational predissociation of HFHCl by overtone excitation of HF
Authors: Mollaaghababa Reza , Chang Huan-C. , Klemperer William
Published: October 2010

The high-resolution laser-induced-fluorescence spectrum of the ν = 3 excitation of the HF stretch in HFHCl is reported. The complex was formed in a supersonic jet of HF and HCl molecules expanded in argon. The HF submolecule was pumped from ν = 0 to ν = 3 by radiation from a Ti: sapphire ring laser operating in the (11–12) × 103 cm−1 range. Both Δν = 1 and ν = 2 emission of the HF fragment were observed by large-area PbS and Ge detectors, respectively. A single band with K″ = 0 and ΔK = 0 for both isotopic species, HFH35Cl and HFH37Cl, was observed. For HFH35Cl the band origin is ν0 = 11 309.122 (11) cm−1, and the rotational constant [Formula: see text]. A perturbation centered at J = 6 in the ν = 3 level is observed for HFH35Cl. The average linewidth of 300 MHz in this overtone region is approximately 10 times greater than that at the fundamental. The linewidths of the vibration–rotation transitions of HFHCl show considerable variations with both Cl isotope and J level. Although the isotopic dependence of the linewidths was observed in the fundamental, no perceptible J-dependence was detected.
The microwave spectrum of the ClS2 free radical
Authors: Fujitake Masaharu , Hirota Eizi
Published: October 2010

The rotational spectrum of the ClS2 free radical in the gaseous phase has been observed in the millimetre- and submillimetre-wave regions. The ClS2 radical was generated by a dc glow discharge in either S2Cl2 or SCl2. Both a- and b-type R-branch transitions, most of which were split into two fine structure components, were detected for both of the 35Cl and 37Cl isotopic species in the ground vibronic state. As expected from the small hyperfine interaction constants reported by an electron spin resonance (ESR) study, the hyperfine structure was resolved for none of the transitions observed in the present study. Analysis of the observed transition frequencies yielded rotational and centrifugal distortion constants and also spin–rotation interaction constants with their centrifugal corrections. The spin–rotation interaction constants obtained in the present study were consistent with g values of the ESR study. The rotational constants of the two isotopic species led to the structure parameters r(S—S) = 1.906 (7) Å, r(S—Cl) = 2.071 (5) Å, and θ(SSCl) = 110.3 (4)°. A harmonic force field was derived from the observed centrifugal distortion constants and inertial defects combined with the ν1 frequency reported in literature on electronic spectroscopy. This harmonic force field yielded the ν2 and ν3 frequencies (445 (21) and 213.0 (2) cm−1, respectively, for 35ClS2), which differed considerably from the values reported previously.
The hyperfine structure of the C1Π–X1Σ+ transition of CuF
Authors: Jakob P. , Sugawara K. , Wanner J. , Bath A. , Tiemann E.
Published: October 2010

The hyperfine structure of the63CuF C1Π –X1Σ+ transition has been studied by laser-induced fluorescence in the sub-Doppler regime. Splittings of the ro-vibronic lines due to interactions with the copper (I = 3/2) and fluorine (I = 1/2) nuclei are observed in the P, Q, and R branches. The various contributions arising from magnetic dipole and from electric quadrupole interaction are specified. Parity dependent and independent terms are required to explain the dissimilar splitting patterns in the Q and the P/R branches. Hyperfine parameters for the C state of copper monofluoride are reported for the first time.
Fourier transform spectroscopy of the Herzberg I bands of O2
Authors: Yoshino K. , Murray J. E. , Esmond J. R. , Sun Y. , Parkinson W. H. , Thorne A. P. , Learner R. C. M. , Cox G.
Published: October 2010

Fourier transform spectroscopic measurements of the absorption bands of the Herzberg I system [Formula: see text] of O2, have been made in the wavelength region 240–270 nm. Rotational line positions are determined with an accuracy of 0.005 cm−1, and rotational term values are presented for the vibrational levels, ν = 4–11. Molecular constants of these levels are also presented. Interactions with the [Formula: see text] state are observed at J = 13 of the ν = 4 level, at J = 16 of the ν = 7 level, and at J = 15 and 24 of the ν = 9 level of the [Formula: see text] state. Another interaction around J = 10 of the ν = 11 level might result from the weakly bound 3Πu state.
Spectroscopy of new CH3OH FIR laser lines pumped by new CO2 laser lines
Authors: Xu Li-Hong , Lees R. M. , Evenson K. M. , Chou C.-C. , Shy J.-T. , Vasconcellos E. C. C.
Published: October 2010

The number of CO2 laser lines available for optical pumping of far-infrared (FIR) lasers has been significantly increased by the development of a new continuous wave (cw) CO2 laser at the Time and Frequency Division of the National Institute of Standards and Technology in Boulder, Colorado. This system operates on very high-J lines of the normal bands as well as on sequence and new hot-band lines, and has generated numerous new FIR laser transitions in CH3OH. These include the new 123 μm world-record holder, pumped by the 9HP(20) hot-band CO2 line, which is now the most efficient known FIR laser line. Assignments are given for a number of the IR pump – FIR laser energy level and transition systems, based on our high-resolution Fourier transform studies of the FIR and IR spectra of CH3OH. Features of the transition system for the 123 μm line and wave numbers for several further potential FIR laser lines are presented.
Identification of triplet levels by Zeeman studies of microwave–optical double resonance in the system of thioformaldehyde
Authors: Weber T. , Hüttner W. , Ramsay D. A.
Published: October 2010

Microwave-optical double resonance experiments have been carried out in the presence of magnetic fields on the 410 band of the [Formula: see text] system of thioformaldehyde. Several anticrossings have been observed. The series of levels 60 6, 70 7, …. 120 12 of the 41 Ã1A2 state is shown to be perturbed by the 63 3, 73 4, …. 123 9 levels of the 21 31 ã3A2 state. Two anticrossings involving high vibronic levels of the ground state (X* levels) are explained by interactions with the 85 level of the 2142 ã3A2 state.
High-resolution infrared emission spectrum of InF
Authors: Karkanis T. , Dulick M. , Morbi Z. , White J. B. , Bernath P. F.
Published: October 2010

A high-resolution infrared emission spectrum of InF was recorded with a Fourier transform spectrometer. A total of 2664 rotational lines from ν = 1 → 0 to ν = 12 → 11 were measured for the major isotopomer 115InF and 179 lines for ν = 1 → 0 and ν = 2 → 1 for the minor isotope 113InF in the X1Σ+ ground state. Revised Dunham Yij constants for each isotopomer as well as isotopically invariant Dunham Uij constants are reported. Also, an effective Born–Oppenheimer potential was determined by fitting the data directly to the eigenvalues of a parameterized potential.
Spectroscopic studies on toluene and some deuterated derivatives. I. Vibrational spectra
Authors: Balfour Walter J. , Fried Yvonne
Published: October 2010

Infrared and Raman data on liquid toluene and nine deuterated derivatives have been examined to provide a consistent set of vibrational assignments. Comprehensive observations and assignments are reported for the four monodeuterated species.
Spectroscopic studies on toluene and some deuterated derivatives. II. Electronic spectra
Authors: Balfour Walter J. , Ram Ram S.
Published: October 2010

The 266.7 nm absorption systems of toluene and seven deuterated isomers were observed at high resolution and analyses of their vibronic structure performed. All in-plane vibrations with ground-state frequencies less than 1000 cm−1 were identified from 0–1 hot bands. The frequencies agree well with data obtained from infrared and Raman studies. The corresponding vibrations were identified in the excited state. Information was also obtained on out-of-plane vibrations with ground-state frequencies less than 650 cm−1, since all of these are found to give sequence structure. A comparison of the measured data for the various isotopic species has enabled a consistent description of the excited state in toluene to be made. Problems associated with errors, ambiguities, and inconsistencies in previously published work have been addressed.
Interference phenomena in two-photon transitions caused by laser-induced ac-Stark effect
Authors: Linskens A. F. , Dam N. , Reuss J. R. , Sartakov B.
Published: October 2010

A system is described in which a real molecular state is tuned into and out of resonance with the intermediate level of a two-photon transition, by the laser-induced ac-Stark effect. Two narrow-band CO2 wave-guide lasers are utilized to induce rovibrational transitions in the ν3 ladder of SF6. A weak probe laser monitors the absorption for the [Formula: see text] two-photon transition. Simultaneously, a strong pump laser is in resonance with the [Formula: see text] one-photon transition. The ac-Stark splitting is observed and quantum interferences between two-photon amplitudes involving different intermediate states occur. It is demonstrated that destructive interference allows suppression of the two-photon excitation for an appropriate pump laser power. Simulations based on the Dressed State Picture and the optical Bloch equations show a satisfactory agreement with the experiment.