bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of quantum interference on tunneling photoionization rates of N2 and O2 molecules
Authors: Mishima K. , Nagaya K. , Hayashi M. , Lin S. H.
Published: March 2005

In this work, we reexamine the photoionization rates of N2 and O2 molecules using the previously published photoionization rate theory which is based on the original atomic Keldysh theory [K. Mishima et al., Phys. Rev. A 66, 033401 (2002); K. Mishima et al., Phys. Rev. A66, 053408 (2002)]. We have found that the constructive quantum interference takes place for N2 molecule while the destructive quantum interference plays an important role for O2 molecule. This is consistent with the experimental and theoretical results reported in the literature. The formulas derived in this paper clearly show that this is due to the different symmetries of the valence orbitals of N2 and O2 molecules.
High electron concentration and mobility in Al-doped n-ZnO epilayer achieved via dopant activation using rapid-thermal annealing
Authors: Kim Kyoung-Kook , Niki Shigeru , Oh Jin-Yong , Song June-O , Seong Tae-Yeon , Park Seong-Ju , Fujita Shizuo , Kim Sang-Woo
Published: March 2005

We report on the growth of very high-quality Al-doped n-type ZnO epilayers on sapphire substrates using a radio-frequency (rf) magnetron sputtering technique combined with a rapid-thermal annealing. Photoluminescence (PL) and Hall measurements show that both the optical and electrical properties of the ZnO layers are significantly improved with an increasing annealing temperature up to 900 °C. For example, the samples that are grown at 600 °C and a rf power of 100 W with an Ar∕O2 gas ratio of 1 give an electron concentration of 1.83×1020cm3 and a mobility of 65.6cm2∕Vs, when annealed at 900 °C for 3 min in a nitrogen ambient. Furthermore, x-ray diffraction measurements show that both the as-grown and annealed samples are of excellent crystallinity.
Nonlinear evolution of a swirling jet instability
Authors: Delbende Ivan , Rossi Maurice
Published: March 2005

The nonlinear evolution of the three-dimensional instability of a viscous unsteady swirling jet, namely, the Batchelor vortex, is addressed. Two types of initial perturbations are considered: a single unstable normal mode with given azimuthal symmetry and white noise. Three different scenarios have been put into evidence according to the value of the swirl number q selected in the unstable range q<1.5. When helical symmetry is present, the dynamics can be interpreted in a two-dimensional framework. More specifically, the process is viewed as the simultaneous action of a destabilizing “instantaneous” swirling jet instability and a stabilizing accelerated viscous diffusion induced by differential rotation. For swirl numbers close to the critical value (1<q<1.5), this latter effect dominates and leads the vortex to relaminarize in the nonlinear regime. For intermediate values of swirl (q∼0.8), it breaks into an array of equal sign vortices containing most of the initial circulation and surrounding a central part with axial velocity. For lower swirl (q<0.6), the initial vortex gives birth to an array of dipoles, the ejection of which drastically increases the structure size. Similar trends are observed on simulations with an initial white noise condition.
Single-crystal Ti2AlN thin films
Authors: Joelsson T. , Hörling A. , Birch J. , Hultman L.
Published: March 2005

We have produced pure thin-film single-crystal Ti2AlN(0001), a member of the Mn+1AXn class of materials. The method used was UHV dc reactive magnetron sputtering from a 2Ti:Al compound target in a mixed Ar–N2 discharge onto (111) oriented MgO substrates. X-ray diffraction and transmission electron microscopy were used to establish the hexagonal crystal structure with c and a lattice parameters of 13.6 and 3.07Å, respectively. The hardness H, and elastic modulus E, as determined by nanoindentation measurements, were found to be 16.1±1GPa and 270±20GPa, respectively. A room-temperature resistivity for the films of 39μΩcm was obtained.
Electrical characteristics of GaN implanted with Si+ at elevated temperatures
Authors: Irokawa Y. , Fujishima O. , Kachi T. , Pearton S. J. , Ren F.
Published: March 2005

Si + implantation at multiple ion energies (30–360keV) into GaN for n-type doping was carried out at substrate temperatures from 27 to 700°C, followed by annealing at 1150–1400°C for 5min. At total doses of 2.0×1014cm−2 (corresponding to an approximately uniform Si concentration of ∼4×1018cm−3), the use of elevated implant temperature does not produce improved electrical characteristics. For anneal temperatures below ∼1300°C, the resulting sheet resistance of the GaN implanted at 700°C was approximately a factor of 2 higher than for room-temperature implantation, mainly through a lower sheet carrier density. At the higher annealing temperatures (>1300°C), elevated implant temperature produced similar sheet resistances to implantation carried out at room temperature. For annealing at 1300°C, the lowest sheet resistances (<700Ω∕◻) and highest activation efficiencies (∼65%) were obtained for implant temperatures <400°C. The most plausible explanation is that at these doses, SiGa (i.e., donor state) site occupation is not a strong function of the initial amount of damage created by the implantation.
Self-organized growth of InAs quantum wires and dots on InP(001): The role of vicinal substrates
Authors: Bierwagen O. , Masselink W. T.
Published: March 2005

We have studied the self-organized growth of InAs nanostructures in an InP matrix by gas-source molecular-beam epitaxy on both nominally oriented and vicinal InP(001). Atomic force microscopy and low-temperature photoluminescence demonstrate that the off-cut direction of vicinal substrates—largely independent of growth conditions—determines the morphology of nanostructures, that is, quantum dot, quantum wire, or two-dimensional growth; whereas, on nominally oriented substrates, the morphology is very strongly dependent on the growth conditions.
Topology optimization of a photonic crystal waveguide termination to maximize directional emission
Authors: Frei W. R. , Tortorelli D. A. , Johnson H. T.
Published: March 2005

Topology optimization based on nonlinear programming techniques and design sensitivity analysis are used to maximize directional emission from a waveguide termination in a two-dimensional square lattice rods-in-air photonic crystal. Maximizing directional emission from a photonic crystal waveguide termination is desirable since a horn antenna style termination of comparable functionality is very large, while small simple terminations show strong angular spread. The optimized waveguide termination designed here is compact and exhibits a fivefold increase in power incident upon the target area over the simple termination. This improvement is achieved by creating surface modes that interfere to produce highly directional emission.
Enhanced Raman scattering for temperature measurement of a laser-heated atomic force microscope tip
Authors: McCarthy Brendan , Zhao Yanming , Grover Ranjan , Sarid Dror
Published: March 2005

Illuminating a silicon cantilever of an atomic force microscope with a focused laser beam creates heat that can be funneled into a nanoscale area at the apex of its tip. To characterize the heating dynamics and measure the temperature of the tip, a Raman scattering pump-and-probe method is used. It is found that at the apex of the tip the intensity of the Raman Stokes and anti-Stokes components are significantly enhanced relative to those obtained on a bulk silicon sample. Modeling the temperature rise at the tip of the cantilever by a closed-form analytical expression gives good agreement with the Raman measurements. This model can be used to design the structure of the cantilever so that the heat delivery to its tip is optimized. Such an optimized cantilever can potentially be used in high-density, heat-assisted magnetic recording, optical data storage using phase-change media and thermomechanical recording systems, for example, where nanoscale heated regions are of importance.
Hysteresis and control of ferromagnetic resonances in rings
Authors: Giesen F. , Podbielski J. , Korn T. , Steiner M. , van Staa A. , Grundler D.
Published: March 2005

The spin dynamics in narrow ferromagnetic rings is studied in the frequency range from 45MHzto20GHz at room temperature. Our broadband spectrometer allows us to monitor the ferromagnetic resonance of characteristic spin configurations as a function of an external field μ0H. We observe hysteresis and irreversible jumps of the resonance frequencies which we attribute to onion-to-vortex and vortex-to-reversed-onion transitions.
Individual Pattern Representations are Context Independent, but their Collectiverepresentation is Context Dependent
Authors: Lachmann Thomas , Van Leeuwen Cees
Published: March 2005

We studied context dependency of the representations underlying perceptual “goodness”. Three experiments used a same– different task with classical Garner 5-dot patterns presented with an interstimulus interval (ISI) of 500 ms. Same patterns were allowed to be rotated or reflected versions of each other. Pattern goodness was varied according to rotation and reflection equivalence, using Garner's equivalence set size (ESS) measure. The ESS of both first and second patterns affected reaction time and accuracy. A model based on assumptions that Garner's equivalence sets constitute the generic representation of these patterns and that items within these sets are accessed serially was fitted to the data. Excellent fits were obtained, which were robust against frequency-induced bias at the level of the individual pattern, but sensitive to such bias at the level of the equivalence set. It was concluded that individual pattern representations are context independent, whereas their collective representations are context dependent. Simplicity and likelihood principles, therefore, seem to apply to different levels of a representation hierarchy.
What makes a route appear longer? An experimental perspective on features, route segmentation, and distance knowledge
Authors: Jansen-Osmann Petra , Berendt Bettina
Published: March 2005

Five experiments performed in a desktop virtual-reality setting investigated the influence of environmental features—that is, noticeable landmarks along the route—on distance estimation. Landmarks were of two types: Either they simply “filled” the route or they “filled” and also segmented it, thereby inducing a hierarchical structuring of the route. Previous research had left the question open of whether a filling or a segmenting feature leads to an overestimation of a distance along the route. Our experiments showed different results dependent on the kind of space: If an environment was learned from a route perspective, filling and segmenting environmental features led to overestimations of distances, while the segmenting of a route induced by a grouping of similar features did not. If the environment was learned from a map that afforded a survey perspective, route structuring induced through a segmenting feature or by phenomenal grouping led to an overestimation of distances, whereas features that merely filled the route did not.
Desipramine Treatment for Cocaine Dependence in Buprenorphine‐ or Methadone‐treated Patients: Baseline Urine Results as Predictor of Response
Authors: Kosten Thomas , Sofuoglu Mehmet , Poling James , Gonsai Kishor , Oliveto Alison
Published: March 2005

The prognostic importance of baseline urines for cocaine was examined in a randomized, placebo‐controlled, twelve‐week clinical trial in 165 opioid‐and cocaine‐dependent patients who were treated with desipramine (DMI) in combination with buprenorphine (BUP) or methadone (Meth). Patients with a cocaine‐positive urine at baseline (CU+) had significantly fewer cocaine‐free urines than those with a negative urine at baseline (CU‐neg). The CU+ patients showed no treatment effects of DMI compared to placebo, but the CU‐neg patients showed a treatment effect of DMI. This DMI effect was significant in patients maintained on BUP but not on Meth.
Medical Symptoms Associated with Tobacco Smoking with and without Marijuana Abuse among Crack Cocaine‐dependent Patients
Authors: Patkar Ashwin A. , Batra Vikas , Mannelli Paolo , Evers‐Casey Sarah , Vergare Michael J. , Leone Frank T.
Published: March 2005

Despite the widespread use of tobacco and marijuana by cocaine abusers, it remains unclear whether combined tobacco and marijuana smoking is more harmful than tobacco smoking alone in cocaine abusers. We investigated the differences in medical symptoms reported among 34 crack cocaine abusers who did not smoke tobacco or marijuana (C), 86 crack cocaine abusers who also smoked tobacco (C + T), and 48 crack abusers who smoked both tobacco and marijuana (C + T + M). Medical symptoms were recorded using a 134‐item self‐report instrument (MILCOM), and drug use was assessed using the Addiction Severity Index (ASI). After controlling for clinical and demographic differences, the C + T + M group reported significantly more total symptoms on the MILCOM as well as on the respiratory, digestive, general, and nose J throat subscales than the C + T or C groups. The C + T group reported higher total and respiratory and nose/ throat symptoms than the C group. However, the C group had the highest number of mood symptoms among the three groups. The C + T and C + T + M groups were comparable in number of cigarettes smoked and ASI scores. Although tobacco smoking is associated with higher reports of medical problems in crack abusers, smoking both marijuana and tobacco seems to be associated with greater medical problems than smoking tobacco alone. Tobacco smoking was not related to changes in cocaine use. Also, marijuana smoking does not appear to be associated with a reduction in tobacco or cocaine use.
A Cross‐study Comparison of Cannabis and Tobacco Withdrawal
Authors: Vandrey Ryan G. , Budney Alan J. , Moore Brent A. , Hughes John R.
Published: March 2005

A valid cannabis withdrawal syndrome has recently been established, but its clinical importance remains unclear. One method to assess the importance of cannabis withdrawal is to compare it with an established withdrawal syndrome. Cannabis and tobacco withdrawal studies that employed similar methods were used to compare six participant‐rated and four observer‐rated symptoms. Descriptive and graphic comparisons indicate that the magnitude and time course of withdrawal effects are similar across the two syndromes. These findings are consistent with other evidence supporting the clinical importance of the cannabis withdrawal syndrome. There remains a need for prospective experimental studies to replicate these findings.
Lack of Hippocampal Volume Change in Long‐term Heavy Cannabis Users
Authors: Tzilos Golfo K. , Cintron Christina B. , Wood Jonas B.R. , Simpson Norah S. , Young Ashley D. , Pope Harrison G. , Yurgelun‐Todd Deborah A.
Published: March 2005

The effects of cannabis smoking on the morphology of the hippocampus are still unclear, especially because previous human studies have examined primarily younger, shorter‐term users. We used magnetic resonance imaging to investigate these effects in a group of 22 older, long‐term cannabis users (reporting a mean [SD] of 20,100 [13,900] lifetime episodes of smoking) and 26 comparison subjects with no history of cannabis abuse or dependence. When compared to control subjects, smokers displayed no significant adjusted differences in volumes of gray matter, white matter, cerebrospinal fluid, or left and right hippocampus. Moreover, hippocampal volume in cannabis users was not associated with age of onset of use nor total lifetime episodes of use. These findings are consistent with recent literature suggesting that cannabis use is not associated with structural changes within the brain as a whole or the hippocampus in particular.
Ego Function as a Correlate of Addiction
Authors: Juni Samuel , Stack Joseph E.
Published: March 2005

Eighty‐nine substance abusers in an urban treatment facility completed the self‐report version of the Ego Function Assessment as well as the Addiction Severity Index. Statistical analyses delineate ego functions that relate to specific disruptions in the social and psychological adaptation of the substance abuser. Distinct profiles of ego functions are highlighted based on patterns of drug abuse and types of treatment referrals, as well as patterns of intravenous drug injection. Education levels are shown to correlate with ego function strengths. Results are interpreted from the social perspective of drug abuse.
European States, American Contexts
Authors: Edling Max. M
Published: March 2005

In order to interpret the debate over the ratification of the US Constitution as a debate over state formation, it is necessary to know something both about the development of the European state in the early modern period and about the ideological response that this development generated. The aim of this chapter is therefore to provide a historical sociology of state building. The first three sections discuss the development of the British state after the Glorious Revolution of 1688–89 (the deposition of James II and the accession of William III and Mary II to the English throne), concentrating on Britain not because it was by far the most common point of reference in the ratification debate, but rather because no other government was nearly as successful as the British when it came to raising taxes and mobilizing resources and men. The emphasis on discussion of Britain is not meant to imply that the Constitution was adopted in order to introduce a British “fiscal‐military state” in America, but rather to demonstrate that there were certain limits to the expansion of the central government in the USA that did not apply in Britain. Precisely for this reason, the state created by the Federalists was very different from the contemporary British state, and the last two sections of the chapter address the basis of these differences.
An Impotent Congress
Authors: Edling Max. M
Published: March 2005

Chapter 5 and the corresponding Ch. 10 in Part Three of the book provide background accounts of political development in the USA from the American War of Independence to the Philadelphia Convention, and establish that, by 1787, Congress was marked by military weakness and financial insolvency. Here, the background is given to the conflict between the Federalists and the Antifederalists over the military clauses of the US Constitution, a conflict that is analyzed in Chs 6–8 (the debate over the fiscal clauses is analyzed in Part Three of the book). It is argued that two principles frustrated the ability of the Confederation Congress to provide the union with the military capacity it needed to function: first, the sovereignty of the states; and, second, the strong aversion in the American political tradition to a peacetime standing army. In the end, these principles led Congress to become passive in foreign affairs. Ends with an attempt to locate the Federalist demand for an improved military capacity of the national state not in the context of militarism, but in the context of the promotion of commerce.
A Government of Force
Authors: Edling Max. M
Published: March 2005

Chapter 7 and the corresponding Ch. 12 in Part Three of the book present the Antifederalist objections to a stronger national government in the “fiscal‐military” sphere, with this chapter looking closely at Antifederalist objections to the military clauses of the US Constitution. The opponents of the Constitution never accepted the Federalist claim that the independence, liberty, and prosperity of the American republic depended on the creation and maintenance of a peace establishment consisting of regular troops, and did not believe that the union faced as serious threats as the Federalists claimed, keeping to the view that standing armies in time of peace were a threat to liberty. Both ancient and modern history had taught that “almost all” nations in Europe and Asia had lost their liberty because of the establishment of a standing army, so it hardly made sense for Americans to imitate them. To Antifederalists, it seemed that if the military clauses of the Constitution were adopted and the Federalists realized their plan to raise a standing army, the people of America would soon find that the Constitution's supporters would make use of it on the domestic rather than the international scene. The Antifederalist criticism of the army clauses therefore said little about commercial treaties and the importance of military strength in international relations; instead, they approached the issue from the traditional British Country perspective, claiming that standing armies in time of peace posed a threat to liberty, that transfer of military power from the states to Congress threatened both the state militia and the state assemblies, and that a standing army would make it possible for the national government to deprive people of their property without their consent by levying and collecting arbitrary taxes – in other words, a standing army in a time of peace was to the Antifederalists an objection to the centralization of power at the expense of the people's ability to withhold consent through their control of strong local institutions.
Metabolic flux analysis of Escherichia coli in glucose-limited continuous culture. I. Growth-rate-dependent metabolic efficiency at steady state
Authors: Kayser Anke , Weber Jan , Hecht Volker , Rinas Ursula
Published: March 2005

The Escherichia coli K-12 strain TG1 was grown at 28 °C in aerobic glucose-limited continuous cultures at dilution rates ranging from 0·044 to 0·415 h−1. The rates of biomass formation, the specific rates of glucose, ammonium and oxygen uptake and the specific carbon dioxide evolution rate increased linearly with the dilution rate up to 0·3 h−1. At dilution rates between 0·3 h−1 and 0·4 h−1, a strong deviation from the linear increase to lower specific oxygen uptake and carbon dioxide evolution rates occurred. The biomass formation rate and the specific glucose and ammonium uptake rates did not deviate that strongly from the linear increase up to dilution rates of 0·4 h−1. An increasing percentage of glucose carbon flow towards biomass determined by a reactor mass balance and a decreasing specific ATP production rate concomitant with a decreasing adenylate energy charge indicated higher energetic efficiency of carbon substrate utilization at higher dilution rates. Estimation of metabolic fluxes by a stoichiometric model revealed an increasing activity of the pentose phosphate pathway and a decreasing tricarboxylic acid cycle activity with increasing dilution rates, indicative of the increased NADPH and precursor demand for anabolic purposes at the expense of ATP formation through catabolic activities. Thus, increasing growth rates first result in a more energy-efficient use of the carbon substrate for biomass production, i.e. a lower portion of the carbon substrate is channelled into the respiratory, energy-generating pathway. At dilution rates above 0·4 h−1, close to the wash-out point, respiration rates dropped sharply and accumulation of glucose and acetic acid was observed. Energy generation through acetate formation yields less ATP compared with complete oxidation of the sugar carbon substrate, but is the result of maximized energy generation under conditions of restrictions in the tricarboxylic acid cycle or in respiratory NADH turnover. Thus, the data strongly support the conclusion that, in aerobic glucose-limited continuous cultures of E. coli TG1, two different carbon limitations occur: at low dilution rates, cell growth is limited by cell-carbon supply and, at high dilution rates, by energy-carbon supply.
Metabolic flux analysis of Escherichia coli in glucose-limited continuous culture. II. Dynamic response to famine and feast, activation of the methylglyoxal pathway and oscillatory behaviour
Authors: Weber Jan , Kayser Anke , Rinas Ursula
Published: March 2005

The metabolic dynamics of theEscherichia coliK-12 strain TG1 to feast and famine were studied in glucose-limited steady-state cultures by up- and downshifts of the dilution rate, respectively. An uncoupling of anabolic and catabolic rates was observed upon dilution rate upshifts, apparent through immediately increased glucose uptake rates which were not accompanied by an immediate increase of the growth rate but instead resulted in the temporary excretion of methylglyoxal,d- andl-lactate, pyruvate and, after a delay, acetate. The energetic state of the cell during the transient was followed by measuring the adenylate energy charge, which increased within 2 min after the upshift and declined thereafter until a new steady-state level was reached. In the downshift experiment, the adenylate energy charge behaved inversely; no by-products were formed, indicating a tight coupling of anabolism and catabolism. Both dilution rate shifts were accompanied by an instantaneous increase of cAMP, presaging the subsequent changes in metabolic pathway utilization. Intracellular key metabolites of the Embden–Meyerhof–Parnas (EMP) pathway were measured to evaluate the metabolic perturbation during the upshift. Fructose 1,6-diphosphate (FDP) and dihydroxyacetone phosphate (DHAP) increased rapidly after the upshift, while glyceraldehyde 3-phosphate decreased. It is concluded that this imbalance at the branch-point of FDP induces the methylglyoxal (MG) pathway, a low-energy-yielding bypass of the lower EMP pathway, through the increasing level of DHAP. MG pathway activation after the upshift was simulated by restricting anabolic rates using a stoichiometry-based metabolic model. The metabolic model predicted that low-energy-yielding catabolic pathways are utilized preferentially in the transient after the upshift. Upon severe dilution rate upshifts, an oscillatory behaviour occurred, apparent through long-term oscillations of respiratory activity, which started when the cytotoxic compound MG reached a threshold concentration of 1·5 mg l−1in the medium.
Comparison of gene expression in trap cells and vegetative hyphae of the nematophagous fungus Monacrosporium haptotylum
Authors: Ahrén Dag , Tholander Margareta , Fekete Csaba , Rajashekar Balaji , Friman Eva , Johansson Tomas , Tunlid Anders
Published: March 2005

Nematode-trapping fungi enter the parasitic stage by developing specific morphological structures called traps. The global patterns of gene expression in traps and mycelium of the fungusMonacrosporium haptotylumwere compared. The trap of this fungus is a unicellular spherical structure called the knob, which develops on the apex of a hyphal branch. RNA was isolated from knobs and mycelium and hybridized to a cDNA array containing probes of 2822 EST clones ofM. haptotylum. Despite the fact that the knobs and mycelium were grown in the same medium, there were substantial differences in the patterns of genes expressed in the two cell types. In total, 23·3 % (657 of 2822) of the putative genes were differentially expressed in knobs versus mycelium. Several of these genes displayed sequence similarities to genes known to be involved in regulating morphogenesis and cell polarity in fungi. Among them were several putative homologues for small GTPases, such asrho1,rac1andras1, and a rho GDP dissociation inhibitor (rdi1). Several homologues to genes involved in stress response, protein synthesis and protein degradation, transcription, and carbon metabolism were also differentially expressed. In the last category, a glycogen phosphorylase (gph1) gene homologue, one of the most upregulated genes in the knobs as compared to mycelium, was characterized. A number of the genes that were differentially expressed in trap cells are also known to be regulated during the development of infection structures in plant-pathogenic fungi. Among them, agas1(mas3) gene homologue (designatedgks1), which is specifically expressed in appressoria of the rice blast fungus, was characterized.
Reduced initiation frequency from oriC restores viability of a temperature-sensitive Escherichia coli replisome mutant
Authors: Skovgaard Ole , Løbner-Olesen Anders
Published: March 2005

ThednaXgene ofEscherichia coliencodesτandγclamp loader subunits of the replisome. Cells carrying the temperature-sensitivednaX2016mutation were induced for the SOS response at non-permissive temperature. The SOS induction most likely resulted from extensive replication fork collapse that exceeded the cells' capacity for restart. Seven mutations in thednaAgene that partly suppressed thednaX2016temperature sensitivity were isolated and characterized. Each of the mutations caused a single amino acid change in domains III and IV of the DnaA protein, where nucleotide binding and DNA binding, respectively, reside. The diversity ofdnaA(Sx) mutants obtained indicated that a direct interaction between the DnaA protein andτorγis unlikely and that the mechanism behind suppression is related to DnaA function. AlldnaA(Sx) mutant cells were compromised for initiation of DNA replication, and contained fewer active replication forks than their wild-type counterparts. Conceivably, this led to a reduced number of replication fork collapses within eachdnaX2016 dnaA(Sx) cell and prevented the SOS response. Lowered availability of wild-type DnaA protein also led to partial suppression of thednaX2016mutation, confirming that thednaA(Sx) mode of suppression is indirect and results from a reduced initiation frequency atoriC.
The pimFABCDE operon from Rhodopseudomonas palustris mediates dicarboxylic acid degradation and participates in anaerobic benzoate degradation
Authors: Harrison Faith H. , Harwood Caroline S.
Published: March 2005

Bacteria in anoxic environments typically convert aromatic compounds derived from pollutants or green plants to benzoyl-CoA, and then to the C7dicarboxylic acid derivative 3-hydroxypimelyl-CoA. Inspection of the recently completed genome sequence of the purple nonsulfur phototrophRhodopseudomonas palustrisrevealed one predicted cluster of genes for theβ-oxidation of dicarboxylic acids. These genes, annotated aspimFABCDE, are predicted to encode acyl-CoA ligase, enoyl-CoA hydratase, acyl-CoA dehydrogenase and acyl-CoA transferase enzymes, which should allow the conversion of odd-chain dicarboxylic acids to glutaryl-CoA, and even-chain dicarboxylic acids to succinyl-CoA. A mutant strain that was deleted in thepimgene cluster grew at about half the rate of the wild-type parent when benzoate or pimelate was supplied as the sole carbon source. The mutant grew five times more slowly than the wild-type on the C14dicarboxylic acid tetradecanedioate. The mutant was unimpaired in growth on the C8-fatty acid caprylate. The acyl-CoA ligase predicted to be encoded by thepimAgene was purified, and found to be active with C7–C14dicarboxylic and fatty acids. The expression of apimA–lacZchromosomal gene fusion increased twofold when cells were grown in the presence of straight-chain C7–C14dicarboxylic and fatty acids. These results suggest that theβ-oxidation enzymes encoded by thepimgene cluster are active with medium-chain-length dicarboxylic acids, including pimelate. However, the finding that thepimoperon deletion mutant is still able to grow on dicarboxylic acids, albeit at a slower rate, indicates thatR. palustrishas additional genes that can also specify the degradation of these compounds.
Peer and teacher ratings of third‐ and fourth‐grade children's social behavior as a function of early maternal employment
Authors: Youngblade Lise M.
Published: March 2005

Background:  One of the more controversial issues related to maternal employment in the United States concerns the timing of entry into the workforce and its effect on children, particularly during the first year of the child's life. Some studies show deleterious effects on children, such as increases in aggression and noncompliance, while others document few negative and even positive effects of early employment.

Methods:  This study examined the long‐term effects of maternal employment during the child's first year of life on the social behavior of 171 third‐ and fourth‐grade children in two‐parent families. The moderating effects of child gender and social class were investigated. The extent to which stability in alternative care arrangements statistically explained links between early maternal employment and child outcomes was tested.

Results:  After controlling for child gender, and maternal ethnicity, social class, and current employment status, third‐ and fourth‐grade children whose mothers were employed during their first year of life evinced more acting out and less frustration tolerance and were nominated more often by peers for ‘hitting’ and ‘being mean’ than children whose mothers were not employed. There was some evidence that these associations were moderated by child gender and social class: boys, but not girls, whose mothers were employed during the first year were subsequently rated by teachers as acting out more than other children, and were also more likely to be nominated by peers for hitting. Higher nominations for hitting were only found in the working class. Finally, there was partial evidence that the number of alternative child‐care arrangements during the first year accounted for the links between early maternal employment and subsequent child outcomes.

Conclusions:  These results are congruent with extant research that posits a risk of early employment on socioemotional development, but show that this risk is partially attributable to child‐care instability.
Word reading and reading‐related skills in adolescents with Williams syndrome
Authors: Levy Yonata , Smith Jason , Tager‐Flusberg Helen
Published: March 2005

Background:  Individuals with Williams syndrome have good spontaneous language despite low levels of intelligence. This study explores the relationship between intelligence, word decoding and reading‐related skills in 20 individuals with Williams syndrome.

Methods:  In addition to the KBIT, the participants were administered standardized measures of reading, vocabulary, rapid naming, phonological skills and an experimental measure of rhyme judgement.

Results:  There was wide variability in the reading achievement among the individuals with WS. While some participants were unable to recognize letters of the alphabet, others scored within the normal range of tests of single word reading and decoding. Reading scores were correlated with intelligence as measured on KBIT matrices but not with the vocabulary measures. Reading also correlated with phonological awareness tasks yet, surprisingly, not with rapid naming.

Conclusion:  It is suggested that in individuals with retardation, intelligence rather than language and language‐related skills predict achievements in word reading.
Gastric myoelectrical and autonomic cardiac reactivity to laboratory stressors
Authors: Gianaros Peter J. , Quigley Karen S. , Mordkoff J. Toby , Stern Robert M.
Published: March 2005

We evaluated the effects of two laboratory stressors (speech preparation and isometric handgrip) on gastric myoelectrical and autonomic cardiac activity, and the extent to which autonomic responses to these stressors and somatization predict reports of motion sickness during exposure to a rotating optokinetic drum. Both stressors prompted a decrease in preejection period (PEP) and respiratory sinus arrhythmia (RSA), and an increase in a dysrhythmic pattern of gastric myoelectrical activity, termed gastric tachyarrhythmia. Stressor‐induced decreases in RSA and higher somatization scores predicted increased reports of motion sickness during drum rotation. These results demonstrate that laboratory stressors concurrently affect gastric myoelectrical activity and autonomic control of the heart, and that stressor‐induced decreases in RSA and higher levels of somatization predict motion sickness susceptibility.
Manipulation of frontal EEG asymmetry through biofeedback alters self‐reported emotional responses and facial EMG
Authors: Allen John J.B. , Harmon‐Jones Eddie , Cavender James H.
Published: March 2005

Individual differences in resting asymmetrical frontal brain activity have been found to predict subsequent emotional responses. The question of whether frontal brain asymmetry can cause emotional responses has yet to be addressed. Biofeedback training designed to alter the asymmetry of frontal brain activity was therefore examined. Eighteen right‐handed female participants were randomly assigned to receive biofeedback training designed to increase right frontal alpha relative to left frontal alpha (n= 9) or to receive training in the opposite direction (n= 9). Five consecutive days of biofeedback training provided signals of reward or nonreward depending on whether the difference between right (F4) and left (F3) frontal alpha exceeded a criterion value in the specified direction. Systematic alterations of frontal EEG asymmetry were observed as a function of biofeedback training. Moreover, subsequent self‐reported affect and facial muscle activity in response to emotionally evocative film clips were influenced by the direction of biofeedback training.
Competition, predation and nest niche shifts among tropical cavity nesters: phylogeny and natural history evolution of parrots (Psittaciformes) and trogons (Trogoniformes)
Authors: Brightsmith Donald J.
Published: March 2005

Nest site selection by birds is a critically important life history trait as competition for suitable sites can be intense, and because birds are at their most vulnerable to predators during nesting. Previous studies show that the clutch size and nestling period evolve in response to competition for nest sites and nest predation, respectively. This provides the opportunity to study the relative contribution of competition and predation to the evolution of nesting niche. Using previously published phylogenies for parrots and trogons, I found evidence for at least 13 independent evolutionary transitions from tree cavities to alternative nesting niches (including termitaria, cliffs, and burrows). I analyzed variations in clutch size, incubation period and nestling period for 16 phylogenetically controlled pairs of species to test the relative roles of competition for tree cavities and nest predation, in favoring evolutionary switches to alternative nest sites. Tree cavity nesting species did not have larger clutch sizes as predicted if competition for tree cavities leads birds to invest heavily in nesting once they obtain a nest site (the limited breeding opportunities hypothesis). Instead I found that shifts to alternative nesting niches were accompanied by an increase in nestling period. As nestling period is a surrogate measure for long‐term nest predation rates, this finding suggests that nest predation has been more important than competition in niche diversification among cavity nesting parrots and trogons. The timing of events in South America suggests that the explosive radiation of mammalian nest predators during the Upper‐Oligocene, Lower‐Miocene (20–30 million years ago) corresponded with the radiation of parrot and trogon taxa that exploit novel nesting niches.
Variability of the origin of the uterine artery: Laparoscopic surgical observation
Authors: Holub Zdenek , Lukac Jan , Kliment Lev , Urbanek Stepan
Published: March 2005

Aim: To categorize the surgical anatomic variants of the origins of the uterine arteries and to clarify the difference in the description of the internal iliac artery in the contemporary anthropologic, radiologic and surgical system.

Methods: One hundred women with symptomatic fibroids were treated using retroperitoneal laparoscopic dissection of the uterine vessels (LDUV). Retrospective evaluation of the operative records and videos was carried out. The anatomical classification of Adachi (type I–V) was modified for surgical purposes (type I–IV).

Results: Laparoscopic retroperitoneal dissection and LDUV were carried out successfully using an ultrasonic operative technique in all women. The branching of the branches of the internal iliac artery was studied on the right side of the pelvis. Of the 100 uterine arteries that were evaluated, 81% were classifiable types and 19% of surgical dissections were inconclusive. Classification was as follows: type I, 30.8%; type II, 23.4%; type III, 45.6%; and type IV was not found. Modified surgical classification type III (visceral branches arising from the umbilical artery and the internal pudendal artery) was claimed to be statistically the most common type.

Conclusion: Laparoscopic dissection of the uterine artery close to the origin of the uterine artery can be carried out safely in the most frequent types of surgical classification. The meticulous dissection of the uterine artery in cases in which the uterine artery does not arise typically from an unobliterated segment of the internal iliac artery was recommended.
Relationship between HIV viral load and Langerhans cells of the cervical epithelium
Authors: Levi Gabriel , Feldman Joseph , Holman Susan , Salarieh Afshin , Strickler Howard D. , Alter Shira , Minkoff Howard
Published: March 2005

Aim: To determine the relationship between the density of cervical mucosa Langerhans cells, cervical histology, and HIV viral load.

Methods: Eighty‐four HIV‐infected and 17 women at high risk for HIV had cervical biopsies assessed for squamous intraepithelial lesions and Langerhans cell density. Langerhans cells were identified using the S‐100 immunohistochemical stain and were counted manually. Polymerase chain reaction assays were used to detect cervical human papillomavirus (HPV)‐DNA. T‐cell subsets were determined using immunofluorescent flow cytometry. Plasma HIV RNA levels were measured using a nucleic acid sequence‐based amplification technique. The associations between cervical Langerhans cell density, cervical histology, CD4 counts, HIV viral loads, HPV‐DNA detection, and smoking status were assessed using multivariate statistical models.

Results: In multivariate analysis among women infected with HIV, the mean Langerhans cell density per high‐powered field was 4.00 among women with no detectable plasma HIV‐RNA, and 1.92 among those with detectable HIV‐RNA (P = 0.01). The mean cervical Langerhans cell density was increased in women with high‐grade squamous intraepithelial lesions compared with those with low‐grade squamous intraepithelial lesions and normal/metaplastic histology (3.87 vs 2.11; P = 0.05). Neither HPV‐DNA detection, smoking status, nor CD4 count was significantly associated with Langerhans cell density.

Conclusions: The decrease in cervical Langerhans cell density in women with detectable HIV‐RNA suggests an impaired mucosal immune response to local infections, such as HPV. Conversely, HPV infection resulting in high‐grade dysplasia might be associated with an enhanced local immune response.
Runoff and soil loss from bench terraces. 2. An event‐ based erosion process model
Authors: Van Dijk A. I. J. M. , Bruijnzeel L. A.
Published: March 2005

Despite widespread bench terracing of rainfed hillsides in upland West Java, soil loss rates remain high. This paper reports measurements of sediment yield from terrace risers and beds and from terrace units made during three consecutive rainy seasons. The results demonstrate that soil loss from the terraces occurs in two stages: rainfall‐driven transport by splash and shallow overland flow (wash) from the terrace riser and bed to a central drain is followed by a combination of onward wash transport of fine sediment and entrainment by runoff of coarser sediment deposited in the drain. A model (TEST: Terrace Erosion and Sediment Transport) was developed, describing these processes as a function of vegetation and soil surface cover and the presence of a layer of deposited sediment. The model was calibrated using some of the measured sediment yield data and subsequently tested by simulating the remaining data. The results were satisfactory and modelled fractions of sediment transported by splash, wash and flow‐driven runoff transport generally compared well with observed fractions of fine and coarse particles in eroded sediment from the various plots.
Proton‐pump inhibitors reduce the risk of uncomplicated peptic ulcer in elderly either acute or chronic users of aspirin/non‐steroidal anti‐inflammatory drugs
Authors: Pilotto A. , Franceschi M. , Leandro G. , Paris F. , Cascavilla L. , Longo M. G. , Niro V. , Andriulli A. , Scarcelli C. , Di Mario F.
Published: March 2005

Background : Although administration of gastroprotective drugs may reduce the risk of peptic ulcers associated with the chronic use of non‐steroidal anti‐inflammatory drugs or aspirin, no consensus exists as to whether this co‐therapy is effective for short‐term prevention, particularly in old age.

Aim : To evaluate the risk of peptic ulcer associated with acute and chronic non‐steroidal anti‐inflammatory drugs or aspirin therapy in elderly subjects, and the influence of antisecretory treatment on this risk.

Methods : The study included 676 elderly non‐steroidal anti‐inflammatory drugs or aspirin users and 2435 non‐users who consecutively underwent upper gastrointestinal endoscopy. The use of non‐steroidal anti‐inflammatory drugs and/or aspirin as well as antisecretory drugs (H2‐blockers and proton‐pump inhibitors) was evaluated by a structured interview. Diagnosis of gastric and duodenal ulcer as well as Helicobacter pylori infection were carried out by endoscopy and histological examination of the gastric mucosa.

Results : About 47.3% of patients were acute and 52.7% chronic users of non‐steroidal anti‐inflammatory drugs or aspirin. The risk of peptic ulcer, adjusted for age, gender, H. pylori infection and antisecretory drug use was higher in acute (gastric ulcer: odds ratio, OR =4.47, 95% CI: 3.19–6.26 and duodenal ulcer: OR =2.39, 95% CI: 1.73–3.31) than chronic users (gastric ulcer: OR = 2.80, 95% CI: 1.97–3.99 and duodenal ulcer: OR = 1.68, 95% CI: 1.22–2.33). Proton‐pump inhibitor treatment was associated with a reduced risk of peptic ulcer in both acute (OR = 0.70, 95% CI: 0.24–2.04) and chronic (OR = 0.32, 95% CI: 0.15–0.67) non‐steroidal anti‐inflammatory drugs/aspirin users. Conversely, concomitant treatment with H2‐blockers was associated with a significantly higher risk of peptic ulcer both in acute (OR = 10.9, 95% CI: 3.87–30.9) and chronic (OR = 6.26, 95% CI: 2.56–15.3) non‐steroidal anti‐inflammatory drugs/aspirin users than non‐users. Proton‐pump inhibitor treatment resulted in an absolute risk reduction of peptic ulcer by 36.6% in acute and 34.6% in chronic non‐steroidal anti‐inflammatory drugs/aspirin users; indeed, the number needed to treat to avoid one peptic ulcer in elderly non‐steroidal anti‐inflammatory drugs/aspirin users was three both in acute and chronic users.

Conclusions : These findings suggest that proton‐pump inhibitor co‐treatment is advisable in symptomatic elderly patients who need to be treated with non‐steroidal anti‐inflammatory drugs and/or aspirin for a short period of time.