bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecological Distributin of Mice in the Medicine Bow Mountains of Wyoming
Authors: Brown Larry N.
Published: May 2006

The distribution of six species of native mice with regard to plant communities, vegetative ground cover, and proximity of water was studied in the Medicine Bow Range of Southern Wyoming. The eight types of plant communities sampled were: mountain mahogany, sagebrush, aspen, subalpine meadow, willow—alder bog, lodgepole pine, spruce—fir, and alpine tundra. The western jumping mounse (Zapus princeps) and long—tailed vole (Microtus longicaudus) both reached their greatest densities in three habitats: Willow—alder, aspen forest, and subalpine meadows. Both species preferred sites adjacent to water and having dense ground cover. The montane vole (Microtus montanus) was most abundant in meadow situations as exemplified by alpine tundra and subalpine forb—sedge meadows. This species preferred moderate to dry situations and dense to intermediate ground cover. The redbacked vole (Clethrionomys gapperi) was by far the most abundant species taken in lodgepole pine and spruce—fir communities. This species occurred commonly at a distance from water and was equally abundant in areas of dense, intermediate, or sparse vegetative ground cover. The heather vole (Phenacomys intermedius) was not trapped in great numbers at any locale but was most frequently taken in subalpine meadows, spruce—fir forest, and alpine tundra, indicating the species is primarily a high altitude form. Heather voles exhibited no preferences with regard to proximity of water or density of ground cover. The deer mouse (Peromyscus maniculatus) was the most widely distributed species studied, but displayed particularly high densities in mountain mahogany and sagebrush communities. The habitats yielding the highest overall mouse production were those located at lower elevations in the mountains, i.e. the sagebrush, mountain mahogany, aspen, and subalpine meadows; while those habitats yielding the lowest number of mice were at highest elevations, i.e. lodgepole pine, spruce—fir, and alpine tundra. The proximity of water seemed to have no clearcut effect on the overall production of mice, although areas of dense cover were on the average twice as productive as those with sparse cover.
A Mathematical Model for Two Tribolium Populations in Competition
Authors: Taylor N. W.
Published: May 2006

If the various parameters describing the behavior of species in competition are known, and the populations at any time are given, then the corresponding populations a short time later can be calculated. In this way a deterministic mathematical model can be set up to imitate the progress of the populations. This model gave a satisfactory result when applied to a particular laboratory experiment.
Primary Productivity and Community Structure of an Estuarine Impoundment
Authors: Lyford John H. , Phinney Harry K.
Published: May 2006

An impounded estuary was employed to study primary productivity, community respiration, and community structure as they related to seasonal and temporal succession, salinity, and water temperature. Metabolism of plankton was studied by the light— and dark—bottle technique; that of the benthic community was determined by using the "diurnal oxygen curve" method. Four different physical environments developed owing to procedures required to control the water in the management of the impoundment. One environment was saline, two were brackish, and one was fresh water. Distinct benthic plant communities developed in each of these environments, and these communities were named according to the dominant plants. An Enteromorpha—Melosira community developed in the saline environment and accounted for the highest metabolic rates of the entire study. A photosynthesis to respiration ((P/R) ratio of 1.36 resulted in the development of a large standing crop which dramatically became senescent during late fall and formed organic ooze on the bottom as well as contributing dissolved and suspended organic matter in the water. The Melosira—Enteromorpha community developed in brackish water and maintained a P/R of 0.76. The Melosira—Spirogyra community developed in the fresh—water environment and maintained a P/R of 0.78, and the Rhizoclonium—Melosira—Synedra community, which developed in brackish water, maintained a P/R of 0.77. The plankton flora was characteristically tychoplankton. The magnitude of the plankton metabolic rates was less than that of the benthic communities. The impoundment maintained a mean P/R of 1.02 over the entire study period, and was essentially autotrophic, primarily owing to the large standing crop developed by the Enteromorpha—Melosira community. Little exogenous organic material appeared to have been imported into the system.
Forest Associations of Southeast Lublin Province, Poland
Authors: Frydman I. , Whittaker R. H.
Published: May 2006

Varied soils and topography support a wide range of forest associations, from raised bog with pine through pine, oak, beech, and fir forests to floodplain alder carr and xeric hazelnut brush. There is no single climatic climax, but beech and fir forests together prevail in the climax pattern. Ten associations were studied by the method of Braun—Blanquet and also subjected to a limited gradient analysis. The associations were arranged in a plexus by community similarity values and in a two—dimensional Wisconsin ordination. Species diversities, Raunkiaer life—forms, and environmental measurements show patterns of change through the pattern of communities represented in the ordinations.
Photosynthesis in Seedlings of Six Conifer Species under Natural Environmental Conditions
Authors: Hodges John D. , Scott David R.
Published: May 2006

Highest average daily rates of net photosynthesis in hemlock, grand fir, Sitka spruce, and Douglas—fir occurred at the outer margin of a forest stand. For Scots pine and noble fir highest rates occurred in an open, fully exposed area. The environment at the stand border apparently resulted in more favorable internal water relations. Species which assimilated best under exposed conditions apparently were better able to control moisture loss than were the other species. Species differed in photosynthetic efficiency. Shade—grown seedlings apparently are capable of higher rates of net photosynthesis than sun—grown plants of the same species.
Significance Testing and Confidence Intervals for Fixed Mortality Rates
Authors: Farris James S.
Published: May 2006

If the mortality rate of individuals in a population is independent of the ages of individuals, 2 populations can be compared with respect to mortality rate by comparing the mean ages at death of samples from the populations. The significance test is of the form F = x1/x2, where the larger sample mean age at death is x1. the F—ratio is two tailed, and its degrees of freedom are 2n1 and 2n2, where n1 is the sample size associated with x1. The test is conservative if the mortality rate increases with age, and biased toward rejection if the mortality rate decreases with age. The quantity 2nx/a, where a is the parameter mean age at death, is chi—square distributed with 2n degrees of freedom if the mortality rate is independent of age. This fact gives a method for constructing confidence intervals for a.
Mortality of Coho Smolts Migrating Through a Lake System
Authors: Allen George H.
Published: May 2006

To study mortality of smolts migrating through a lake and river system, single fin—marked fingerling coho salmon (Oncorhynchus kisutch) of the 1950 brood year were released in 1952 at two points within the Lake Washington drainage, Puget Sound, Washington. Coho smolts migrating through 56 km of lake and river system before entering Puget Sound suffered about 22% greater mortality than coho migrating only 8 km (5 miles). Factors possibly biasing the result were assessed for the experiment, especially the need for equal fishing and natural mortality on test lots of fish while in the ocean.
Influence of a Wildfire in the Wichita Mountains Wildlife Refuge, Oklahoma
Authors: Penfound William T.
Published: May 2006

A devastating wildfire in the Wichita Mountains Wildlife Refuge, August 1—6, 1963, destroyed the aerial parts of nearly all the trees in certain areas. Revegetation was observed during the following 3 years. Although considerable coppice was produced by Quercus stellata and Q. marilandica, very little was consumed by browsing animals. No coppice was produced by Juniperus virginiana. Much of the predominant Andropogon scoparius was destroyed. Utilization of grasses in the burned areas by bison was tremendous, but decreased gradually from 1964 through 1966. In ungrazed plots certain plants appeared during the first growing season and disappeared thereafter. However, Conyza canadensis reached a peak during the second year after the burn (1965) but disappeared the next year (1966). Another group of plants increased throughout the period of study, especially Ambrosia psilostachya, Andropogon gerardi, Muhlenbergia sobolifera, and Panicum malacophyllum. The severely burned areas apparently will revert to grassland or shrubland since tree reproduction has been very meager.
The Pisaster‐Tegula Interaction: Prey Patches, Predator Food Preference, and Intertidal Community Structure
Authors: Paine Robert T.
Published: May 2006

The herbivorous gastropod Tegula funebralis is not highly ranked in a food preference hierarchy of its major predator, the starfish Pisaster ochraceus, and exhibits a persistent broad overlap with it in the rocky intertidal zone at Mukkaw Bay, Washington. Observations on Tegula over a 5—yr period indicate that it settles high intertidally, lives there for 5—6 yr, and then tends to migrate lower into contact with Pisaster. Tegula lays down an annual growth line permitting it to be aged and a growth curve constructed. Analysis of relative growth and reproduction indicates that beyond a certain size (16 mm) large individuals perform less well in the upper than those in the lower intertidal zone. Pisaster consumes 25—28% of the adult Tegula per year in the area of spatial overlap, based on analysis of the age structure of 6—17 yr old Tegula, and by direct estimates of the percentage of the standing crop consumed annually. The relationship between Pisaster and sex ratio, relative energy limitation and reproductive output (fitness) of Tegula is discussed for three subpopulations. It is suggested that the implied results of the interaction is typical of that between a major predator and one of its less preferred prey. The prominent zonation exhibited by preferred prey, the observed intimacy of association of predator and less preferred prey, and the zoogeographic homogeneity of the Pacific rocky coastline community are discussed in relation to three intermeshing ecological processes.
Invertebrate Life Cycle Patterns in the Benthos of a Floodplain Lake in Minnesota
Authors: Heuschele Ann S.
Published: May 2006

This was a study of seasonal distribution of dominant benthic macroinvertebrates in Pickerel Slough, a Mississippi River floodplain lake in Minnesota. The lake was shallow–0.75 m deep during the summer–and had a relatively uniform benthic habitat with no rooted aquatic plants. The total number of benthic macroinvertebrates was greatest in the late fall and winter; they decreased rapidly in the spring owing to emergence of dipterans and decrease in number of oligochaetes. Congeneric species demonstrated three patterns of life cycle interrelationships. Complete seasonal replacement was found for Tanypus: T. stellatus produced two summer generations and probably overwintered as eggs, whereas T. neopunctipennis overwintered as larvae. Overlapping seasonal replacement was shown by Procladius: the largest P. culiciformis preceded P. bellus in both emergence and larval growth. Although both populations were present in the sediments at the same time, they always maintained larval size difference. Overlapping seasonal replacement combined with annual substitution was demonstrated by Chironomus. The largest species, C. plumosus, was the first to have growing larvae in the fall, and this was followed by the growth of the two smaller species: C. near staegeri, and C. decorus. C. plumosus and C. decorus predominated in alternate years. There was a population of growing dipteran larvae at all times during the year. The dominant populations (Chaoborus punctipennis, Chironomus spp., Procladius spp., and Tanypus stellatus) had the growing larval stages of their life cycles spaced so that they did not overlap, thus reducing the competition between them.
The Fates of Immatures in Mixtures of Two Housefly Strains
Authors: Bryant Edwin H.
Published: May 2006

This study analyzes ecological factors determining numbers of adults produced in pure and mixed larval populations of two strains of houseflies, Orlando No. 1 (OL) and green—eye (ge), at low and high density. In pure and mixed cultures at low density, survival of OL was greater than that of ge. However mixtures significantly facilitated survival of ge, while lowering their mean dry weights. The interaction in mixtures resulted from 1) higher mortality in late hatching, smaller larvae; 2) more such in ge than in OL; 3) lack of a substance in ge, produced in OL, that enhances yeast growth. These factors lead to fewer deaths of small ge larvae in mixtures, resulting in increased mean survival while lowering mean adult weight. In pure cultures at high density, performance of ge was greater than that of OL because lower egg hatching in ge made more food available per individual. In mixtures OL is superior to ge owing to a faster feeding and growth rate relative to a constant critical weight for completing development.
Diplopods as Carnivores
Authors: Hoffman Richard L. , Payne Jerry A.
Published: May 2006

Compilation of scattered literature records, together with unpublished observations by the authors, provides an impression that carnivory is not uncommon among various species of Diplopoda. Most of the species known to consume food of animal origin are obviously omnivores, but members of at least one order, the Callipodida, appear to be preferentially carnivorous. On the basis of existing information, omnivory seems to be most common among members of the least specialized taxonomic groups.
Attractant‐Repellent Secretions of Blind Snakes (Leptotyphlops Dulcis) and Their Army Ant Prey (Neiv Amyrmex Nigrescens)
Authors: Watkins Julian F. , Gehlbach Frederick R. , Kroll James C.
Published: May 2006

Blind snakes prey upon and travel with army ants. These snakes are attracted to army ant worker secretions, which may originate in the head and be deposited with the ant trail pheromone. The army ant secretions, especially skatole, repel certain ophiophagous and insectivorous snakes. Similarly, the blind snake cloacal sac substance, known to repel army ants, also repels sympatric ophiophagous and insectivorous snakes. Blind snakes are attracted to their own cloacal sac substance. The function of intraspecific attraction is viewed as most important in this complex system of chemical regulation. Interspecific attraction and repulsion is secondary. For blind snakes, the repulsion of their predators and competitors may be more important than repulsion of ants.
Density‐Dependent Natural Selection
Authors: Roughgarden Jonathan
Published: May 2006

Density—dependent selective values illustrate the evolutionary effect of population—regulating processes that diminish an individual's probability of survival with increased crowding. The selective values, assumed to decrease as a linear function of density, lead in a mild environment to the evolution of phenotypes having a high carrying capacity, K, at the expense of a low intrinsic rate of increase, r. A graphical technique shows that selection causes evolution of phenotypes having a high r at the expense of a low K in harsh seasonal environments. A mathematical technique developed for analyzing evolution in coarse—grained seasonal environments reveals genetic mechanisms, including ones with full dominance, with which a moderately harsh seasonal environment causes stable polymorphism between high—r and high—K genes. The energy balance equation demonstrates the role of high—r and high—K phenotypes in the population's energy flow. A high—r phenotype makes a large expected contribution to the population's productivity under conditions of negligible crowding, and a high—K phenotype has, for a given contribution to the population's productivity under uncrowded conditions, a low sensitivity to having that contribution diminished by crowding.
Aggregation of concentrated polymer latex in stirred vessels
Authors: Vaccaro Andrea , Šefčík Ján , Wu Hua , Morbidelli Massimo , Bobet Josselin , Fringant Christophe
Published: May 2006

An assessment of the relative magnitude of the timescales of mixing and aggregation of fully destabilized polymeric latices in stirred vessels is presented. It is demonstrated that, in industrially relevant conditions (that is, volume fractions above 10% and primary aggregate sizes below 200 nm), latices aggregate and possibly gel before complete mixing is achieved. By means of focused beam reflectance measurements, we measure on‐line and in situ the size of aggregates obtained aggregating a PVDC latex at salt concentrations above the critical coagulation concentration in a stirred vessel operated in semibatch. Several experimental runs are conducted and averages of the aggregate size distribution, that is, volume and number averages, are measured at various values of the feed flowrate, feed solid volume fraction, stirring speed and final volume fraction in the vessel. It is found that at high feeding volume fractions aggregates instantaneously aggregate and gel on entering the vessel. Resulting aggregates are then broken down to volume weighted average sizes falling in the range between 100 and 400 microns at steady state. The experimental results are interpreted in terms of a competition between the aggregation/gelation process and mixing. In particular, by evaluating the relevant characteristic times, it is found that the process is dominated by the competition between mesomixing at the location, where the latex enters the vessel and the aggregation/gelation process. Scanning electron micrographs of dry samples obtained after thermal treatment show aggregate morphologies which further support the above interpretation. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Clinical and epidemiological findings in patients with central ray deficiency: Split hand foot malformation (SHFM) in Manitoba, Canada
Authors: Elliott Alison M. , Reed Martin H. , Chudley Albert E. , Chodirker Bernard N. , Evans Jane A.
Published: May 2006

We conducted a clinical population study to examine the incidence and epidemiology of split hand foot‐malformation (SHFM) in Manitoba from 1957 to 2003. The total number of births during this period was 850,742. Forty‐three patients with SHFM were identified, resulting in an incidence of 1 in 19,784 births. Most patients were ascertained through referrals to the Section of Genetics and Metabolism at the Children's Hospital, Winnipeg, Manitoba. Overall, 22 (51.2%) of affected individuals were females and 21 (48.8%) were male. The left upper limb (LUL) was the most frequently affected, (in 46.5% of patients). The right hand was involved in 39.5%. In 4 patients (9.3%) all four limbs were affected. SHFM is classified as a failure of formation of parts according to the International Federation of Surgical Societies of the Hand (IFSSH) and has also been categorized as Typical or Atypical. Individuals in the Manitoba cohort were classified into two main categories: Typical (29 cases) and Atypical (3 cases). However, 11 patients were not easily placed into either group and comprised a distinct category termed “difficult to classify.” Patients in the three groups were then further subdivided depending on whether or not they had additional congenital anomalies. These complex patients included those with single gene disorders in which SHFM has been reported (e.g., ectodermal dysplasia Ectrodactyly Clefting (EEC), tibial aplasia with SHFM, fibular aplasia with SHFM), as well as those with other recognized or unknown patterns of anomalies. Two had deletions involving 9q and 5p respectively. Unlike some other studies, we did not find an excess of males or right‐sided defects and only two of the cases—two sisters—were related. © 2006 Wiley‐Liss, Inc.
Evaluating therapeutic targets for reperfusion‐related brain hemorrhage
Authors: Maier Carolina M. , Hsieh Lily , Crandall Trisha , Narasimhan Purnima , Chan Pak H.
Published: May 2006

Objective

Early reperfusion after an ischemic stroke can cause blood–brain barrier injury with subsequent cerebral edema and devastating brain hemorrhage. These complications of early reperfusion, which result from excess production of reactive oxygen species, significantly limit the benefits of stroke therapies. In this article, we use a novel animal model that facilitates identification of specific components of the reperfusion injury process, including vascular injury and secondary brain damage, and allows assessment of therapeutic interventions.

Methods

Knock‐out (KO) mice containing 50% manganese‐superoxide dismutase activity (SOD2‐KO) and transgenic mice overexpressing SOD2 undergo transient focal ischemia and reperfusion followed by assessment of infarct, edema, hemorrhage rates, metalloproteinase activation, and microvascular injury.

Results

SOD2‐KO mice demonstrate delayed (>24h) blood–brain barrier breakdown associated with activation of matrix metalloproteinases, inflammation, and high brain hemorrhage rates. These adverse consequences are absent in wild‐type littermates and minocycline‐treated SOD2‐KO animals. Increased hemorrhage rates also are absent in SOD2 overexpressors, which have reduced vascular endothelial cell death. Finally, we show that the tight junction membrane protein, occludin, is an early and specific target in oxidative stress‐induced microvascular injury.

Interpretation

This model is ideal for studying ischemia/reperfusion‐induced vascular injury and secondary brain hemorrhage and offers a unique opportunity to evaluate antioxidant‐based neurovascular protective strategies as potential adjunct treatments to currently approved stroke therapies such as thrombolysis and endovascular clot retrieval.Ann Neurol 2006
The Preparation and Characterisation of Hetero‐ and Homobimetallic Complexes Containing Bridging Naphthalene‐1,8‐dithiolato Ligands
Authors: Aucott Stephen M. , Duerden Daniel , Li Yang , Slawin Alexandra M. Z. , Woollins J. Derek
Published: May 2006

Homo‐ and heterobimetallic complexes of the form [(PPh3)2(μ2‐1,8‐S2‐nap){MLn}] (in which (1,8‐S2‐nap)=naphtho‐1,8‐dithiolate and {MLn}={PtCl2} (1), {PtClMe} (2), {PtClPh} (3), {PtMe2} (4), {PtIMe3} (5) and {Mo(CO)4} (6)) were obtained by the addition of [PtCl2(NCPh)2], [PtClMe(cod)] (cod=1,5‐cyclooctadiene), [PtClPh(cod)], [PtMe2(cod)], [{PtIMe3}4] and [Mo(CO)4(nbd)] (nbd=norbornadiene), respectively, to [Pt(PPh3)2(1,8‐S2‐nap)]. Synthesis of cationic complexes was achieved by the addition of one or two equivalents of a halide abstractor, Ag[BF4] or Ag[ClO4], to [{Pt(μ‐Cl)(μ‐η2:η1‐C3H5)}4], [{Pd(μ‐Cl)(η3‐C3H5)}2], [{IrCl(μ‐Cl)(η5‐C5Me5)}2] (in which C5Me5=Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl), [{RhCl(μ‐Cl)(η5‐C5Me5)}2], [PtCl2(PMe2Ph)2] and [{Rh(μ‐Cl)(cod)}2] to give the appropriate coordinatively unsaturated species that, upon treatment with [(PPh3)2Pt(1,8‐S2‐nap)], gave complexes of the form [(PPh3)2(μ2‐1,8‐S2‐nap){MLn}][X] (in which {MLn}[X]={Pt(η3‐C3H5)}[ClO4] (7), {Pd(η3‐C3H5)}[ClO4] (8), {IrCl(η5‐C5Me5)}[ClO4] (9), {RhCl(η5‐C5Me5)}[BF4] (10), {Pt(PMe2Ph)2}[ClO4]2 (11), {Rh(cod)}[ClO4] (12); the carbonyl complex {Rh(CO)2}[ClO4] (13) was formed by bubbling gaseous CO through a solution of 12. In all cases the naphtho‐1,8‐dithiolate ligand acts as a bridge between two metal centres to give a four‐membered PtMS2 ring (M=transition metal). All compounds were characterised spectroscopically. The X‐ray structures of 5, 6, 7, 8, 10 and 12 reveal a binuclear PtMS2 core with Pt⋅⋅⋅M distances ranging from 2.9630(8)–3.438(1) Å for 8 and 5, respectively. The napS2 mean plane is tilted with respect to the PtP2S2 coordination plane, with dihedral angles in the range 49.7–76.1° and the degree of tilting being related to the Pt⋅⋅⋅M distance and the coordination number of M. The sum of the Pt(1)coordination plane/napS2 angle, a, and the Pt(1)coordination plane/M(2)coordination plane angle, b, a+b, is close to 120° in nearly all cases. This suggests that electronic effects play a significant role in these binuclear systems.
Density Functional Study of Methyl Chemisorption on Polycyclic Aromatic Hydrocarbons
Authors: Unterreiner Barbara V. , Carissan Yannick , Klopper Wim
Published: May 2006

The reactions of methyl radicals with large (up to C96H24) polycyclic aromatic hydrocarbons (PAHs) are studied by density functional calculations to shed light on the experimentally observed deposition of carbon on highly oriented pyrolytic graphite (HOPG), which occurs when hot HOPG (decorated by nanometre‐sized defects) is exposed to methyl radicals. The equilibrium structures of the reaction products, together with transition structures for PAHs up to the size of phenanthroperylene, are determined using the density functionals B3LYP, TPSSh, BP86 and TPSS. The structures are analysed by computing the π orbital axis vector (POAV) and the altitude of the reactive carbon above the molecular plane of the PAH. The strongest CCH3 bonds are found at the edges of the PAHs, where the s character of the C orbital involved in the bond is roughly 25 % (sp3 hybrid orbital). Carbon atoms inside the PAH form bonds with the methyl radical through atomic orbitals with about 16 % s character in the POAV analysis. These bonds are much weaker than those at the edges of the PAH, while the reactive carbon has moved about 40 pm above the molecular plane. At the edges, the PAH carbon atoms do not leave the molecular plane to this extent. The computed barrier heights and geometrical parameters of the transition structures are in agreement with Hammond’s postulate, and the relative energies of all of the equilibrium structures can be rationalized by Hückel molecular orbital (HMO) theory.
Cover Picture: Hydrogen Electrocatalysis (ChemPhysChem 5/2006)
Authors: Kibler Ludwig A.
Published: May 2006

The cover picture shows an ordered array of 400 palladium clusters deposited onto a gold single‐crystal surface in sulfuric acid solution (courtesy of F. Simeone and D. M. Kolb). This image (200 nm×200 nm, average cluster height around 1 nm) was not only recorded in situ by scanning tunneling microscopy, the palladium clusters were also fabricated with the tip of the microscope. The Minireview by Kibler on page 985 addresses relations between the local surface structure of noble metal surfaces and their activity for the hydrogen evolution reaction. Variations in the hydrogen chemisorption energy for different active centres have an impact on the overall reaction kinetics.
A Theoretical Study on Structures, Bonding Energies and Aromaticity of Two New Series of Dinuclear Phosphametallocenes: (η5‐P5)MM′(η5‐P5) and (η5‐C5H5)MM′(η5‐P5) (M, M′ = Zn, Cd)
Authors: Liu Zi‐Zhong , Tian Wei Quan , Feng Ji‐Kang , Zhang Gang , Li Wei‐Qi , Cui Yan‐Hong , Sun Chia‐Chung
Published: May 2006

The equilibrium geometries, the energies, the harmonic vibrational frequencies, and the nucleus independent chemical shifts (NICSs) of the ground state of (η5‐P5)MM′(η5‐P5) and (η5‐C5H5)MM′(η5‐P5) (M, M′ = Zn, Cd) are calculated by the hybrid density functional method B3LYP with LANL2DZ basis sets. The analysis of energy and harmonic frequencies on the equilibrium geometries of both series dinuclear deca‐ and pentaphosphametallocenes shows that all the minima with singlet electronic state have an staggered (9 ° ≤D(E–M–M–E′) ≤ 36°) conformation except for the eclipsed CpCd2(P5) (C5v), and all the D5h and the D5d symmetric conformations are transition states while the energy differences between the most stable minimum and the transition states are very small (≤ 0.1 kcal/mol), thus, the rotation of the P5 ring about M–M bond in all complexes is almost free. The analysis of the NBO, the Laplacian of the electron density, the electrostatic interaction energy, the bonding energy decomposition, and the molecular orbital correlation diagrams for the two series complexes reveals that the properties of all the dinuclear phosphametallocenes investigated are similar to that of the dizinc metallocenes. The M–M (or M–M′) bond in the dinuclear phosphametallocenes is a weak σ covalent bond, and the magnitude of bonding energy of the M–M (or M–M′) bond correlates with the energy difference between the energy of HOMO in M(η5‐P5) (or MCp) (2A, C5v) fragment and the energy of HOMO‐2 in [MM′(η5‐P5)2] (1A, D5, or D5h) [or (η5‐P5)MM′Cp (1A, C5, or C5v)] (M, M′ = Zn, Cd). The strength of the M–M (or M–M′) bond plays a decisive role on the stability of the dinuclear phosphametallocenes. However, the M–(η5‐P5) (or M–Cp) bonding mainly is ionic. Among the different dinuclear phosphametallocenes with the same ligands, the bonding energies of the M–M (or M–M′) bond and of the M–(η5‐P5) (or M–Cp) bond decrease as M varying from Zn to Cd. Among the different phosphametallocenes with the same metals, the bonding energies of the M–M (or M–M′) bond and the M–ligand bond increase with ligand varying from the (η5‐P5) to the Cp. The negative NICSs indicate that all dinuclear phosphametallocenes have aromaticity. The various dissected bond NICS contributions reveal that the NICS contributions of the metal–ligand bond, the metal–metal bond, and the metal lone pair electrons to the overall aromaticity in the Zn‐containing dinuclear phosphametallocenes are different from their counterpart contributions in the Cd‐containing dinuclear phosphametallocenes, such difference causes that the overall NICSs of the Zn‐containing dinuclear phosphametallocenes are more negative than that of the Cd‐containing dinuclear phosphametallocenes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
A Mild Stereo‐ and Enantiospecific Conversion of 2,3‐Diaryl‐Substituted Oxiranes into 2,2‐Dimethyl‐1,3‐Dioxolanes by an Acetone/Amberlyst 15 System
Authors: Solladié‐Cavallo Arlette , Choucair Elias , Balaz Milan , Lupattelli Paolo , Bonini Carlo , Di Blasio Nadia
Published: May 2006

Amberlyst 15 is an efficient catalyst for the reaction of aryl‐substituted oxiranes with acetone to prepare 2,2‐dimethyl‐1,3‐dioxolanes in high yields. trans‐2,3‐Diaryloxiranes afford trans‐acetonides enantiospecifically at room temperature, and the use of enantiopure 2,3‐diaryloxiranes results in no loss of stereochemical integrity in the resulting trans‐acetonides. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
One‐Pot Three‐Component Synthesis of 3‐Halofurans and 3‐Chloro‐4‐iodofurans
Authors: Karpov Alexei S. , Merkul Eugen , Oeser Thomas , Müller Thomas J. J.
Published: May 2006

A novel sequence of Sonogashira coupling and acid‐mediated nucleophilic addition to the ynone intermediate with concomitant deprotection and cyclocondensation opens a new one‐pot synthetic access to 3‐chloro‐, 3‐iodo‐, and 3‐chloro‐4‐iodo‐furans in moderate to good yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Partitioning resistance to overland flow on rough mobile beds
Authors: Hu Shixiong , Abrahams Athol D.
Published: May 2006

For overland flows transporting predominantly bed load over rough mobile beds without rainfall, resistance to flow f may be divided into four components: surface resistance fs, form resistance ff, wave resistance fw, and bed‐mobility resistance fm. In this study it is assumed that f = fs + ff + fw + fm, and an equation is developed for each component. The equations for fs and ff are borrowed from the literature, while those for fw and fm are developed from two series of flume experiments in which the beds are covered with various concentrations of large‐scale roughness elements. The first series consists of 65 experiments on fixed beds, while the second series contains 194 experiments on mobile beds. All experiments were performed on the same slope (S = 0·114) and with the same size of sediment (D = 0·00074 m). The equations for fw and fm are derived by a combination of dimensional analysis and regression analysis. The analyses reveal that the major controls of fw and fm are the Froude number F and the concentration of the roughness elements Cr. When the equations for fw and fm are summed, the Cr terms cancel out, leaving fw+m = 0·63F−2. An equation is developed that predicts total f, and the contributions of fs, ff, fw and fm to f are computed from the series 1 and 2 experiments. An analysis of the first series reveals that in clear‐water flows over fixed beds, fw accounts for 52 per cent of f. A similar analysis of the second series indicates that in sediment‐laden flows over mobile beds fw comprises 37 per cent and fm 32 per cent of f, so that together fw and fm account for almost 70 per cent of f. Finally, regression analyses indicate that where F > 0·5, fw and fm each vary with F−2 and fw/fm = 1·18. The equation developed here for predicting total f applies only to the range of hydraulic, sediment, and bed roughness conditions represented by the experimental data. With additional data from a broader range of conditions the same methodology as employed here could be used to develop a more general equation. Copyright © 2006 John Wiley & Sons, Ltd.
Transcription factor co‐expression patterns indicate heterogeneity of oligodendroglial subpopulations in adult spinal cord
Authors: Kitada Masaaki , Rowitch David H.
Published: May 2006

Oligodendrocytes and their precursors serve critical roles in the maintenance of neurological function. Although activity of the transcription factors (TFs) Olig1, Olig2, Sox10, and Nkx2.2 is required during early oligodendrocyte development, their later expression in adult central nervous system is rather poorly characterized. Here we have analyzed co‐expression patterns of these transcriptional proteins in the mouse cervical spinal cord. Our findings indicate that TF co‐expression patterns describe heterogeneity in adult oligodendroglial populations (1) in distinct sub‐regions of grey and white matter and (2) with respect to level of maturation from proliferating precursors to myelinating oligodendrocytes. Our findings suggest that TF co‐expression patterns identify and might regulate distinct functional classes of grey and white matter oligodendroglia. © 2006 Wiley‐Liss, Inc.
Extraction of Candida rugosa lipase from aqueous solutions into organic solvents by forming an ion‐paired complex with AOT
Authors: Wu Jin Chuan , Chua Pei Song , Chow Yvonne , Li Ruijiang , Carpenter Keith , Yu Hongwei
Published: May 2006

Candida rugosa lipase was extracted from aqueous solutions into organic solvents by forming an ion‐paired complex with sodium bis(2‐ethylhexyl)sulfosuccinate (AOT). The optimal aqueous pH for lipase recovery was 4.5 and the optimal CaCl2 concentration was 10 mmol dm−3. The lipase recovery decreased with increasing aqueous enzyme concentration but increased with increasing AOT concentration in the organic phase. The presence of polar co‐solvents in the aqueous phase did not obviously improve the lipase recovery, which was also little influenced by the type of hydrophobic organic solvent used for solubilising AOT. Surprisingly, no detectable activity of the ion‐paired C. rugosa lipase was observed for both the esterification of lauric acid with 1‐propanol in isooctane and the hydrolysis of olive oil in isooctane containing an appropriate amount of water. The ion‐paired C. rugosa lipase mediated the enantioselective crystallisation of racemic ketoprofen in isooctane, indicating the feasibility of using it as a chiral mediator for the enantioseparation of hydrophobic racemic compounds in organic systems. Copyright © 2006 Society of Chemical Industry
Intraoperative sonographically guided resection of hemangioblastoma in the cerebellum
Authors: Wang Yi , Wang Yong , Gao Xiang , Wang Yida
Published: May 2006

We report a case of hemangioblastoma in a 37‐year‐old woman. Intraoperative sonography was used to significantly reduce the duration of the intervention and ensure thorough resection of the tumor. We recommend real‐time intraoperative sonography as a routine procedure in the surgical treatment of hemangioblastoma. © 2006 Wiley Periodicals, Inc. J Clin Ultrasound 34:247–249, 2006
Enlarged lymph nodes in porta hepatis: Sonographic sign of chronic hepatitis B and C infections
Authors: Kuo Hsing‐Tao , Lin Ching‐Yih , Chen Jyh‐Jou , Tsai Sun‐Lung
Published: May 2006

Purpose.

Enlarged lymph nodes in the hepatoduodenal ligament are prevalent in chronic infection with hepatitis B virus (HBV) or hepatitis C virus (HCV); however, the clinical significance of this sonographic finding in an endemic area is unknown.

Methods.

Six hundred outpatients were categorized into 4 groups (nonviral, HBV, HCV, and HBV and HCV) using viral markers. The prevalence and size of enlarged lymph nodes were compared. Correlation between clinical parameters and nodal size was evaluated.

Results.

The incidence of detectable nodes in both the HBV group and the HCV group was significantly increased (56.9% and 69.4%, respectively; both p < 0.001) compared with the nonviral group; this rate was independent of aminotransferase levels. Nodal width was the only significant parameter when viral and nonviral groups were compared (p < 0.05). If a width of more than 5 mm was used to predict HBV or HCV infection, the positive predictive rate was 88% and the specificity was 89%.

Conclusions.

Lymph nodes in the hepatoduodenal ligament, especially those wider than 5 mm, suggest chronic HBV or HCV infection instead of only chronic hepatitis, especially in an endemic area such as Taiwan. © 2006 Wiley Periodicals, Inc. J Clin Ultrasound 34:211–216, 2006
Doppler ultrasound assessment of posterior tibial artery size in humans
Authors: Sabatier Manning J. , Stoner Lee , Reifenberger Matt , McCully Kevin
Published: May 2006

Purpose.

The difference between structural remodeling and changes in tone of peripheral arteries in the lower extremities has not been evaluated. The purpose of this study was to (1) evaluate the day‐to‐day reproducibility and interobserver reliability (IOR) of posterior tibial artery (PTA) diameter measurements and (2) evaluate the effect of posture on PTA diameter at rest (Drest), during 10 minutes of proximal cuff occlusion (Dmin), and after the release of cuff occlusion (Dmax), as well as range (Dmax − Dmin) and constriction [(Dmax − Drest)/(Dmax − Dmin) × 100] in vivo.

Methods.

We used B‐mode sonography to image the PTA during each condition.

Results.

Day‐to‐day reliability was good for Drest (intraclass correlation coefficient [ICC] 0.95; mean difference 4.2%), Dmin (ICC 0.93; mean difference 5.4%), and Dmax (ICC 0.99; mean difference 2.2%). The coefficient of repeatability for IOR was 70.5 μm, with a mean interobserver error of 4.7 μm. The seated position decreased Drest (2.6 ± 0.2 to 2.4 ± 0.3 mm; p = 0.002), increased Dmin (2.1 ± 0.2 to 2.4 ± 0.2 mm; p = 0.001), and decreased Dmax (3.1 ± 0.4 to 2.8 ± 0.3 mm; p < 0.001) compared with the supine position. The seated position also decreased arterial range (Dmax − Dmin) from 0.9 ± 0.2 to 0.5 ± 0.1 mm (p = 0.003) and increased basal arterial constriction from 57 ± 19% to 105 ± 27% (p = 0.007).

Conclusions.

The system employed for measuring PTA diameter yields unbiased and consistent estimates. Furthermore, lower extremity arterial constriction and range change with posture in a manner consistent with known changes in autonomic activity. © 2006 Wiley Periodicals, Inc. J Clin Ultrasound 34:223–230, 2006
Heel pad thickness and athletic activity in healthy young adults: A sonographic study
Authors: Uzel Murat , Cetinus Ercan , Ekerbicer H. Cetin , Karaoguz Ahmet
Published: May 2006

Purpose.

The aim of this study was to investigate the sonographic changes of heel fat pad thickness and compressibility index in healthy young adults in relation to level of athletic activity.

Materials and Methods.

One hundred ten young adults (55 women and 55 men) with a body mass index between 18.5 and 24.9 were divided into 3 groups according to their athletic activity level: group 1, sedentary (n = 50); group 2, athletic activity <7 hours/week (n = 30); and group 3, athletic activity ≥7 hours/week (n = 30). The loaded heel pad thickness (LHPT) and unloaded heel pad thickness (ULHPT) were measured via sonography, and the heel pad compressibility index (HPCI) was calculated.

Results.

The mean values of ULHPT, LHPT, and HPCI in group 1 were similar to those of group 2 (p > 0.05) and group 3 (p > 0.05). The mean values of ULHPT, LHPT, and HPCI were similar in the left and right feet in the 3 groups (p > 0.05). There was no correlation between level of athletic activity and ULHPT, LHPT, or HPCI.

Conclusions.

The heel pad thickness and HPCI of individuals engaging in athletic activity up to an average of 11 hours/week were similar to those of sedentary individuals. © 2006 Wiley Periodicals, Inc. J Clin Ultrasound 34:231–236, 2006
Ribbed moraine stratigraphy and formation in southern Finnish Lapland
Authors: Sarala Pertti
Published: May 2006

Characteristics of ribbed moraines, the dominating moraine type in southern Finnish Lapland, have been studied in detail. The ridges are composed of several till units, of which the bottommost units consist of mature basal tills and the surficial parts are enriched with local, short‐transport rock fragments and boulders in till and at the surface of ridges. As a result of this re‐examination a two‐step model of the formation process of ribbed moraines is presented. In the first stage, while cold‐based conditions prevailed, both the bottommost part of the ice sheet and the frozen, substrate fractured under compressive ice flow. Following glacial transport of fractured blocks and formation of the transverse ridge morphology, erosion between the ridges continued owing to freeze–thaw process under variable pressure conditions. In the areas with a low pre‐existing till sheet, the process caused quarrying of the bedrock surface and subsequent deposition of rock fragments and boulders under high pressure on the next ridge. The most suitable conditions for ribbed moraine formation existed during Late Weichselian deglaciation, after the Younger Dryas when the climate warmed very quickly, leading to an imbalance between a warm glacier surface and a cold base. Copyright © 2006 John Wiley & Sons, Ltd.
Event driven electrical stimulation of the dorsal penile/clitoral nerve for management of neurogenic detrusor overactivity in multiple sclerosis
Authors: Fjorback Morten Voss , Rijkhoff Nico , Petersen Thor , Nohr Mads , Sinkjaer Thomas
Published: May 2006

Aims

The aim of this study was to evaluate the effect of automatic event driven electrical stimulation on the dorsal penile/clitoral nerve for management of neurogenic detrusor overactivity in patients suffering from Multiple Sclerosis.

Methods

A total of 10 patients participated in the study. Detrusor pressure was recorded during physiological filling of the bladder and electrical stimulation was applied with surface electrodes whenever the detrusor pressure exceeded 10 cm H2O.

Results

In seven of the eight patients, where neurogenic detrusor overactivity was observed an average of 12 detrusor contractions could be inhibited by stimulation. In one patient, however, stimulation failed to inhibit the detrusor contractions. The average increase in bladder volume from first suppressed detrusor contraction until leakage was 94% (range: 22–366%). On average, the time from first suppressed contraction until leakage was 15 min and 50 sec (range: 4 min 58 sec–32 min 5 sec) with an average physiological filling rate of 8 ml/min. Urgency was effectively suppressed at the onset of stimulation.

Conclusions

The results indicate that involuntary detrusor contractions in patients with multiple sclerosis can effectively be inhibited with event driven stimulation, hereby improving bladder capacity and reducing the number of incontinence episodes. However, the used method for detecting detrusor contractions is not suitable in a chronic setting and alternative techniques needs to be investigated if stimulation should be applied automatically. Neurourol. Urodynam. © 2006 Wiley‐Liss, Inc.
Parasitoid wasp sting: A cocktail of GABA, taurine, and β‐alanine opens chloride channels for central synaptic block and transient paralysis of a cockroach host
Authors: Moore Eugene L. , Haspel Gal , Libersat Frederic , Adams Michael E.
Published: May 2006

The wasp Ampulex compressa injects venom directly into the prothoracic ganglion of its cockroach host to induce a transient paralysis of the front legs. To identify the biochemical basis for this paralysis, we separated venom components according to molecular size and tested fractions for inhibition of synaptic transmission at the cockroach cercal‐giant synapse. Only fractions in the low molecular weight range (<2 kDa) caused synaptic block. Dabsylation of venom components and analysis by HPLC and MALDI‐TOF‐MS revealed high levels of GABA (25 mM), and its receptor agonists β‐alanine (18 mM), and taurine (9 mM) in the active fractions. Each component produces transient block of synaptic transmission at the cercal‐giant synapse and block of efferent motor output from the prothoracic ganglion, which mimics effects produced by injection of whole venom. Whole venom evokes picrotoxin‐sensitive chloride currents in cockroach central neurons, consistent with a GABAergic action. Together these data demonstrate that Ampulex utilizes GABAergic chloride channel activation as a strategy for central synaptic block to induce transient and focal leg paralysis in its host. © 2006 Wiley Periodicals, Inc. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006
Effects of electron irradiation on poly(vinylidene fluoride–trifluoroethylene) copolymers studied by solid‐state nuclear magnetic resonance spectroscopy
Authors: Wang Liying , Zhao Xingzhong , Feng Jiwen
Published: May 2006

The effects of electron irradiation on the molecular chemical structure, conformation, mobility, and phase transition of vinylidene fluoride (VDF) and trifluoroethylene (TrFE) copolymer have been investigated with variable‐temperature, solid‐state 19F nuclear magnetic resonance (NMR). It has been found that electron irradiation converts all‐trans conformations of both VDF‐rich and TrFE‐containing segments into dynamically mixed trans–gauche conformations accompanied by a simultaneous ferroelectric‐to‐paraelectric (or amorphous) transition. The variable‐temperature 19F magic‐angle‐spinning spectra results show that the paraelectric phase melts at much lower temperatures in irradiated films than in an unirradiated sample. Moreover, 19F NMR relaxation data (spin–lattice relaxation times in both the laboratory and rotating frames) reveal that electron irradiation enhances the molecular motion in paraelectric regions, whereas the molecular motion in a high‐temperature amorphous melt (>100 °C) is more constrained in irradiated films. Besides these physical changes, electron irradiation also induces the formation of several CF3 groups. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1714–1724, 2006