bluuebunny/crossref_metadata_2025 huggingface dataset:
Iodine oxide in the Dead Sea Valley: Evidence for inorganic sources of boundary layer IO
Authors: Zingler Jutta , Platt Ulrich
Published: April 2005

The importance of iodine oxide (IO) in tropospheric boundary layer chemistry has been well established in the last decade. Iodine‐containing radicals have been detected in regions of high biological productivity. To date, most explanations assume biogenic precursors (e.g., emission of iodocarbons). In a 2 week field campaign at the Dead Sea, Israel, IO was found to exceed the detection limit (0.3–2 parts per trillion (ppt)) almost daily, with peak levels topping 10 ppt. Macro algae are nonexistent because of the water's high salinity. The Dead Sea's microbiology is discussed in detail, and organic sources of iodine oxide are found to be of minor importance. Thus the site can be treated as a unique place for the investigation of inorganic sources of IO. Such processes have recently been included in model studies. Our study focuses on the first direct evidence for inorganic sources of reactive boundary layer iodine. Heterogeneous iodine release induced by photolysis, liquid phase ozone reactions, or catalytic HOX interactions are discussed as well as NOx chemistry.
Synoptics of dust transportation days from Africa toward Italy and central Europe
Authors: Barkan J. , Alpert P. , Kutiel H. , Kishcha P.
Published: April 2005

The mean synoptic situation associated with dust outbreaks from the Sahara into the central Mediterranean was examined on a daily basis for the month of July from 1979 to 1992. Composite patterns of wind, geopotential heights, and temperature for dusty days versus those for all days were analyzed. Dusty days were defined as days with the Total Ozone Mapping Spectrometer Aerosol Index (TOMS‐AI) in the area around the Apennine peninsula (36°N–46°N, 10°E–18°E) equal to or greater than their monthly average plus 1 standard deviation. It was found that the strength and position of two essential features of the circulation patterns, such as the trough emanating southward from the Icelandic low and the eastern cell of the subtropical high, are the governing factors in making suitable flows for the Saharan dust transportation toward Italy. The deep, well‐developed trough near the Atlantic coasts of Europe and Africa, penetrating well to the south, and the strong eastern cell of the subtropical high situated to the northeast from North Africa near the Mediterranean coast, cause strong south‐southwestern flows with the potential to carry dust northward into the Mediterranean. In extreme cases the dust can reach Europe north of the Alps and even northern Europe, reaching the shores of the Baltic. These warm flows, accompanied by high dust load, also cause considerable warming in the central Mediterranean region of the order of 6–8 K at 700 hPa. Alternatively, the weak western trough and the weak eastern subtropical cell cause westerlies, which are inconsistent with the Mediterranean dust intrusions. Analysis of the extreme intrusion cases in July 1988, based on TOMS‐AI data, and several others in July 2001–2003, based on lidar measurements in Rome, demonstrates the synoptic situation that allows the Saharan dust to reach Italy.
Premonsoon shortwave aerosol radiative forcings over the Arabian Sea and tropical Indian Ocean: Yearly and monthly mean variabilities
Authors: Ramachandran S.
Published: April 2005

The yearly and monthly mean variations in the clear‐sky shortwave aerosol direct radiative forcings are estimated over Coastal India (CI), the Arabian Sea (AS), and tropical Indian Ocean (TIO) during winter monsoon seasons of 1996–2000. The 5‐year mean TOA forcings are estimated to be −10, −9, and −4 W m−2 over CI, AS, and TIO. Surface (SFC) forcings are estimated to be −29, −22, and −5 W m−2 over CI, AS, and TIO, respectively. Atmosphere absorptions are quite large over CI and AS at +19 and +13 W m−2, indicating a significant influence of soot emitted from fossil fuel, biomass burning, and mineral dust. The yearly and monthly mean aerosol forcings are found to exhibit variations. The large atmospheric absorption estimated over CI and AS is found to be a feature of the other polluted ocean and land regions. The influence of relative humidity on the aerosol forcing is estimated. It is shown that as the single scattering albedo increases, the TOA forcing increases while the SFC forcing decreases. With an increase in aerosol optical depths the forcings at TOA and SFC are found to increase substantially, while an increase in the asymmetry parameter is found to decrease both TOA and SFC forcings. The effective factors (forcing at 80% RH/forcing at 30% RH) for the surface are found to be about 1.2 over CI, AS, and 1.4 over TIO. The effective factors estimated over these oceanic regions are found to be smaller than those obtained over the southeastern United States and the mid‐Atlantic coast, indicating that the composition of aerosols found over these regions is different.
1.48 - μ m emission properties and energy transfer between Tm3+ and Ho3+∕Tb3+ in Ge–Ga–As–S–CsBr glasses
Authors: Song Jay Hyok , Heo Jong , Park Se Ho
Published: April 2005

Emission properties of Tm3+ in (0.85−x)(Ge0.25As0.10S0.65)–0.15GaS3∕2–xCsBr glass (x=0–0.17) were investigated. With 15mol% CsBr addition, the emission intensity of 1.48-μm increased accompanied by a large increase in the lifetime of the Tm3+:H43 level up to 1.2ms. At the same time, a 1.48-μm emission peak splits into two peaks due to the changes in the local structure surrounding Tm3+ ions. To achieve population inversion in Tm3+ ions, Ho3+ or Tb3+ were codoped into 0.70(Ge0.25As0.10S0.65)–0.15GaS3∕2–0.15CsBr glass. The population of the Tm3+:F43 level was effectively quenched with Ho3+ or Tb3+ codoping. Critical distances of Tm3+:F43→Ho3+:I75 and Tm3+:F43:→Tb3+:F0,1,27 energy transfer were 9.1 and 12.7Å, respectively. The population density differences were higher with Ho3+ codoping than with Tb3+ due to the crossrelaxation of Tm3+:H43→H53 to Tb3+:F67→F37.
Assignment in the near-threshold absorption spectrum of N2
Authors: Lefebvre-Brion Hélène
Published: April 2005

The absorption spectrum of N2, just above the first ionization limit, in the region between 125 750 and 126600cm−1, is dominated by two broad features which have the appearence of the towers of a “cathedral.” Recently, this energy region has been measured by Sommavilla et al. [J. Phys. B 35, 3901 (2002)] with a resolution of 0.04cm−1 and an assignment for one of these two bands has been suggested. In order to discuss this assignment, we have solved the coupled-channel Schrödinger equation with the parameters of Spelsberg and Meyer above the v=28 level of the b′∑u+1 state for determining the high levels of b′. Furthermore, we evaluate the autoionization widths and the rotational structure of the different possible assignments. Finally, we propose as assignment for the second tower of the cathedral the Rydberg state (AΠu2v+=1)3′d′σgΠu1.
Phase transition in single crystal Cs2Nb4O11
Authors: Liu Jianjun , Kharitonova E. P. , Duan Chun-Gang , Mei W. N. , Smith R. W. , Hardy J. R.
Published: April 2005

We studied temperature dependence of complex capacitance, impedance, and polarized Raman spectra of single crystal Cs2Nb4O11. First, we observed a sharp λ-shaped peak at 165 °C in the complex capacitance, then found drastic changes in the Raman spectra in the same temperature range. Utilizing the pseudosymmetry search of structure space group, we attributed the observed anomalies to a structural change from the room temperature orthorhombic Pnn2 to another orthorhombic Imm2. We also measured room temperature polarized Raman spectra in different symmetries of normal vibrations and assigned high wavenumber Raman bands to the internal vibrations of NbO6 octahedra and NbO4 tetrahedra.
Microwave dielectric properties of tunable capacitors employing bismuth zinc niobate thin films
Authors: Park Jaehoon , Lu Jiwei , Stemmer Susanne , York Robert A.
Published: April 2005

Parallel plate capacitors employing Bi1.5Zn1.0Nb1.5O7 (BZN) thin films with the pyrochlore structure were fabricated on platinized sapphire substrates. The total device quality factor and capacitance were analyzed in the microwave frequency range (up to 20 GHz) by measuring reflection coefficients with a vector network analyzer. The parasitics due to the probe pads were extracted from the measurements. The total device quality factor, which included losses from the dielectric and the electrodes, was more than 200 up to 20 GHz for devices with an area of 100μm2. Based on the frequency dependence of the impedance, series losses of unknown origin appear to dominate the device quality factor at higher frequencies. No significant dispersion in the device capacitance, as would be associated with a dielectric relaxation of BZN, was measured. The large electric field tunability of the permittivity of BZN films and the high device quality factors make these films attractive for voltage controlled microwave devices.
An elementary derivation of the hard/soft-acid/base principle
Authors: Ayers Paul W.
Published: April 2005

The hard/soft-acid/base (HSAB) principle indicates that hard acids prefer binding to hard bases (often forming bonds with substantial ionic character) while soft acids prefer binding to soft bases (often forming bonds with substantial covalent character). Though the HSAB principle is a foundational concept of the modern theory of acids and bases, the theoretical underpinnings of the HSAB principle remain murky. This paper examines the exchange reaction, wherein two molecules, one the product of reacting a hard acid and a soft base and the other the product of reacting a soft acid with a hard base, exchange substituents to form the preferred hard–hard and soft–soft product. A simple derivation shows that this reaction is exothermic, proving the validity of the HSAB principle. The analysis leads to the simple and conceptually appealing conclusion that the HSAB principle is a driven by simple electron transfer effects.
Low threshold edge emitting polymer distributed feedback laser based on a square lattice
Authors: Vasdekis A. E. , Turnbull G. A. , Samuel I. D. W. , Andrew P. , Barnes W. L.
Published: April 2005

We report the demonstration of a low-threshold, edge-emitting polymer distributed feedback laser based on a square lattice. The lattice constant was 268 nm, which corresponds to a lattice line spacing in the ΓM symmetry direction of the Brillouin zone of 189 nm. The latter was employed to provide feedback at 630 nm via a first order diffraction process. The device operated on two longitudinal modes, which were situated on the band-edge near the M symmetry point. The two modes had thresholds of 0.66 nJ and 1.2 nJ—significantly lower than comparable surface-emitting DFB lasers. Angle dependent photoluminescence experiments were performed to investigate the effect of the square lattice on the laser operation and the origin of the low threshold.
Soft magnetic ternary iron-boron-based bulk metallic glasses
Authors: Lin Chih-Yuan , Tien Hung-Yu , Chin Tsung-Shune
Published: April 2005

Ternary iron-boron-based bulk metallic glasses (BMGs) were explored exhibiting capability of thick amorphous casting at least 1mm in rod diameter or 0.5mm in plate thickness, excellent soft magnetic properties with saturation magnetization 1.56T and coercivity smaller than 40A∕m, and electrical resistivity larger than 200μΩcm. The BMG alloys represented by the formulas MaFebBc are based on two simple selection rules: (1) M is an element with an atomic radius at least 130% that of Fe; (2) M possesses eutectic points with both Fe and B, and the M-Fe eutectic is at the Fe-rich end. Among more than 30 candidate M elements, Sc, Y, Dy, Ho, and Er fulfill BMG capability at the composition range, in at %, 3<a<10, 18<c<27, whereas a+b+c=100. It is very remarkable that with a tiny addition of M, such as 4 at %, the critical cooling rate to form an amorphous state is abruptly lowered by more than four orders of magnitude as compared with Fe-B binary alloys, and a bulk amorphous state is achievable with only three elements (conventional ones 4–7 elements). These alloys are promising as core materials for transformers.
Nanotransfer printing of organic and carbon nanotube thin-film transistors on plastic substrates
Authors: Hines D. R. , Mezhenny S. , Breban M. , Williams E. D. , Ballarotto V. W. , Esen G. , Southard A. , Fuhrer M. S.
Published: April 2005

A printing process for high-resolution transfer of all components for organic electronic devices on plastic substrates has been developed and demonstrated for pentacene (Pn), poly (3-hexylthiophene) and carbon nanotube (CNT) thin-film transistors (TFTs). The nanotransfer printing process allows fabrication of an entire device without exposing any component to incompatible processes and with reduced need for special chemical preparation of transfer or device substrates. Devices on plastic substrates include a Pn TFT with a saturation, field-effect mobility of 0.09cm2(Vs)−1 and on/off ratio approximately 104 and a CNT TFT which exhibits ambipolar behavior and no hysteresis.
Fiber-coupled random laser
Authors: Noginov M. A. , Fowlkes I. N. , Zhu G.
Published: April 2005

We demonstrate that in fiber-coupled random laser, the threshold energy is twofold reduced and the slope efficiency is fivefold increased when the tip of the fiber is relocated from the surface to the depth of the powder volume. High absorption efficiency, 85%, and high conversion efficiency of population inversion to stimulated emission, 90%, make fiber-coupled random laser a promising laser source. The demonstrated 5% quantum slope efficiency of the “ready to use” random laser emission delivered by the fiber can probably be significantly increased after the optimization of the coupling of emission to the fiber.
The Différance between Society and Space: Nested Scales and the Returns of Spatial Fetishism
Authors: Collinge Chris
Published: April 2005

By using a framework of spatial categories to illuminate social change, scale analysis intersects with a series of arguments that have been put forward over the years regarding the relationship between society and space. The coherence of scale analysis and its contribution to our understanding of this relationship are examined here, with a focus particularly upon the influential writings of Swyngedouw. It is argued that these writings are haunted by a spatial fetishism that has deconstructive consequences, confounding the distinction between society and space upon which their composition depends. But this conclusion points (through a sort of ‘spectral logic’) towards a wider deconstruction, which suggests that the distinction between these terms or realms is itself the product of a kind of ‘scaling’. Despite its centrality to the development of geographical thought, and its congruence with other dualisms such as culture/nature, the juxtaposition of society and space remains the unexamined ground of much contemporary writing. Recent efforts by feminists and others to rework the notion of ‘space’ and indeed of ‘society’ would benefit from addressing these together in their articulation through the in-between-ness of scale.
The nucleotide switch in Cdc42 modulates coupling between the GTPase-binding and allosteric equilibria of Wiskott–Aldrich syndrome protein
Authors: Leung Daisy W. , Rosen Michael K.
Published: April 2005

The GTP/GDP nucleotide switch in Ras superfamily GTPases generally involves differential affinity toward downstream effectors, with the GTP-bound state having a higher affinity for effector than the GDP-bound state. We have developed a quantitative model of allosteric regulation of the Wiskott–Aldrich syndrome protein (WASP) by the Rho GTPase Cdc42 to better understand how GTPase binding is coupled to effector activation. The model accurately predicts WASP affinity for Cdc42, activity toward Arp2/3 complex, and activation by Cdc42 as functions of a two-state allosteric equilibrium in WASP. The ratio of GTPase affinities for the inactive and active states of WASP is appreciably larger for Cdc42–GTP than for Cdc42–GDP. The greater ability to distinguish between the two states of WASP makes Cdc42–GTP a full WASP agonist, whereas Cdc42–GDP is only a partial agonist. Thus, the nucleotide switch controls not only the affinity of Cdc42 for its effector but also the efficiency of coupling between the Cdc42-binding and allosteric equilibria in WASP. This effect can ensure high fidelity and specificity in Cdc42 signaling in crowded membrane environments.
Linker histone variants control chromatin dynamics during early embryogenesis
Authors: Saeki Hideaki , Ohsumi Keita , Aihara Hitoshi , Ito Takashi , Hirose Susumu , Ura Kiyoe , Kaneda Yasufumi
Published: April 2005

Complex transitions in chromatin structure produce changes in genome function during development in metazoa. Linker histones, the last component of nucleosomes to be assembled into chromatin, comprise considerably divergent subtypes as compared with core histones. In all metazoa studied, their composition changes dramatically during early embryogenesis concomitant with zygotic gene activation, leading to distinct functional changes that are still poorly understood. Here, we show that early embryonic linker histone B4, which is maternally expressed, is functionally different from somatic histone H1 in influencing chromatin structure and dynamics. We developed a chromatin assembly system with nucleosome assembly protein-1 as a linker histone chaperone. This assay system revealed that maternal histone B4 allows chromatin to be remodeled by ATP-dependent chromatin remodeling factor, whereas somatic histone H1 prevents this remodeling. Structural analysis shows that histone B4 does not significantly restrict the accessibility of linker DNA. These findings define the functional significance of developmental changes in linker histone variants. We propose a model that holds that maternally expressed linker histones are key molecules specifying nuclear dynamics with respect to embryonic totipotency.
Polyamines preferentially interact with bent adenine tracts in double-stranded DNA
Authors: Lindemose Søren , Nielsen Peter E. , Møllegaard Niels Erik
Published: April 2005

Polyamines, such as putrescine, spermidine and spermine, have indirectly been linked with the regulation of gene expression, and their concentrations are typically increased in cancer cells. Although effects on transcription factor binding to cognate DNA targets have been demonstrated, the mechanisms of the biological action of polyamines is poorly understood. Employing uranyl photo-probing we now demonstrate that polyamines at submillimolar concentrations bind preferentially to bent adenine tracts in double-stranded DNA. These results provide the first clear evidence for the sequence-specific binding of polyamines to DNA, and thereby suggest a mechanism by which the cellular effects of polyamines in terms of differential gene transcriptional activity could, at least partly, be a direct consequence of sequence-specific interactions of polyamines with promoters at the DNA sequence level.
Differential Effects of MK801 and Lorazepam on Heart Rate Variability in Adolescent Rhesus Monkeys (Macaca Mulatta)
Authors: Bennett Allyson J , DePetrillo Paolo B
Published: April 2005

Previous research shows that ketamine significantly alters cardiac signal regulation in rhesus monkeys, however relatively little is known about the mechanism for this effect. In the study reported here the relative contributions of NMDA receptor activation on cardiac signal dynamics were determined by administering a specific NMDA antagonist, MK801, to rhesus monkeys. The general effects of sedation were assessed by measuring cardiac response to lorazepam, a sedative drug without direct NMDA receptor activity. Electrocardiographic signal dynamics were examined before and after I.V. administration of either MK801 (0.16 mg/kg) or lorazepam (0.48 mg/kg). Inter-beat interval time series data were analyzed in the frequency domain after Fourier transform, and a nonlinear measure of autocorrelation, the Hurst exponent (H), was derived. After MK801 administration, log [HF /Total power] increased post-infusion (M = 1.11, SD = 0.45) compared with pre-infusion values [M = −0.19, SD = 0.32, F(1,4) = 19.49, P = 0.01] while H decreased, mean pre versus post 0.52+/−S.D. 0.10 versus 0.01+/− 0.05, P = 0.0002. Lorazepam administration did not significantly alter heart rate variability measures obtained in the frequency or nonlinear domains. To our knowledge, this is the first study that has defined the effects of peripherally administered MK801 on cardiovascular dynamics in primates and establishes that peripheral administration of NMDA antagonists result in large increases the high-frequency components of cardiac rhythm and increased heart rate variability compatible with MK801-associated increases in parasympathetic outflow.
Endogenous Estrogens Increase Postischemic Hyperemia in the Skin Microcirculation
Authors: Stojanovic Vesna , Küng Fides , Spieker Lukas E , Binggeli Christian , Sudano Isabella , Hayoz Daniel , Lüscher Thomas F , Noll Georg
Published: April 2005

Estrogens have been recognized as a major regulator of vascular tone and structure, particularly in the skin. The objective of this study was to investigate the effects of endogenous estrogens on the skin microcirculation. Skin blood flow was measured at the forearm at rest and during postischemic hyperemia using laser Doppler flowmetry in 32 healthy women (mean age 34.5 ± 3.9 years) involved in an in-vitro fertilization program. Women were treated for 10 to 12 days with gonadotropin-releasing hormone agonist (total dose 40.3 ± 3.3 mg) and human menopausal gonadotropin (1942 ± 801 IE) or follicle-stimulating hormone (2544 ± 1071 IE) according to individual estrogen levels. Plasma estrogen levels increased from 132 ± 90 pmol/L (36 ± 25 pg/mL) to 8471 ± 4386 pmol/L (2308 ± 1195 pg/mL) during treatment (P < 0.0001). Maximal hyperemic blood flow increased from 353 ± 81% before treatment to 516 ± 144% after hormonal stimulation (P < 0.0001), whereas basal skin flow was not altered. This study shows that endogenous estrogens enhance the postischemic hyperemic response of the skin microcirculation.
Mediation of the Effect of Nicotine on Kir6.1 Channels by Superoxide Anion Production
Authors: Hanna Salma Toma , Cao Kun , Sun Xianfeng , Wang Rui
Published: April 2005

KATP channels are a complex of regulatory sulfonylurea receptor subunits and the pore-forming inward rectifiers such as Kir6.1. Using the whole-cell patch-clamp technique, we investigated the interaction of nicotine with the Kir6.1 subunit as well as the underlying mechanism. Stable expression of Kir6.1 in HEK-293 cells yielded a detectable inward rectifier KATP current. This inward current was significantly inhibited by PNU-37883A and by a specific anti-Kir6.1 antibody. Nicotine at 30 and 100 μM increased Kir6.1 currents by 42 ± 11.8% and 26.2 ± 14.6%, respectively (n = 4-6, P < 0.05). In contrast, nicotine at 1-3 mM inhibited Kir6.1 currents (P < 0.05). Nicotine at 100 μM increased the production of superoxide anion (O2
.-) by 20.3 ± 5.7%, whereas at 1 mM it significantly decreased the production of O2
.- by 37.7 ± 4.3%. Coapplication of hypoxanthine (HX) and xanthine oxidase (XO) to the transfected HEK-293 cells resulted in a significant and reproducible increase in Kir6.1 currents (P < 0.05). The stimulatory effect of HX/XO on Kir6.1 current was abolished by tempol, a scavenger of O2
.-. Tempol also abolished the stimulatory effect of 30 μM nicotine on Kir6.1 currents. In conclusion, nicotine stimulates Kir6.1 channel at least in part through the production of O2
.-.
Triptans Induce Vasoconstriction of Human Arteries and Veins from the Thoracic Wall
Authors: Wackenfors Angelica , Jarvius Malin , Ingemansson Richard , Edvinsson Lars , Malmsjö Malin
Published: April 2005

A common side effect of migraine treatment with triptans is chest symptoms. The origin of these symptoms is not known. The aim of the present study was to examine the vasocontractile effect of triptans in human arteries and veins from the thoracic wall and in coronary artery bypass grafts. In vitro pharmacology experiments showed that the 5-hydroxytryptamine (5-HT) type 1B and 1D receptor agonists, eletriptan, naratriptan, rizatriptan, sumatriptan, and zolmitriptan, induced vasoconstriction in the thoracic blood vessels from 38% to 57% of the patients. 5-carboxamidotryptamine (5-CT) and sumatriptan elicited a vasoconstriction that was antagonized by the 5-HT1B receptor antagonist SB224289, whereas the 5-HT1D receptor antagonist BRL115572 had no effect. 5-HT induced a contraction that was inhibited by the 5-HT2A receptor antagonist ketanserin. 5-HT2A, 5-HT1B, and 5-HT1D receptor mRNA levels were detected by real-time PCR in all blood vessels studied. In conclusion, triptans induce vasoconstriction in arteries and veins from the thoracic wall, most likely by activation of 5-HT1B receptors. This response could be observed in only 38% to 57% of the patients, which may provide an explanation for why a similar number of patients experience chest symptoms as a side effect of migraine treatment with triptans.
The Pivotal Roles of the Plant S-Adenosylmethionine Decarboxylase 5′ Untranslated Leader Sequence in Regulation of Gene Expression at the Transcriptional and Posttranscriptional Levels
Authors: Hu Wen-Wei , Gong Haibiao , Pua Eng Chong
Published: April 2005

S-Adenosylmethionine decarboxylase (SAMDC; EC 4.1.1.50) is a key rate-limiting enzyme located in the polyamine biosynthesis pathway. When compared with other organisms, the plant SAMDC genes possess some distinct features because they are devoid of introns in the main open reading frame (ORF) but have an intron(s) in their 5′ untranslated leader sequences, in which two overlapping tiny and small upstream ORFs (uORFs) are present. Our results show that the presence of the 5′ leader sequence plays important roles in transcriptional and posttranscriptional regulation of SAMDC expression. This sequence may help to keep the transcript of its downstream cistron at a relatively low level and function together with its own promoter in response to external stimuli or internal changes of spermidine and spermine to initiate and regulate SAMDC expression. Under stress and high spermidine or spermine conditions, the tiny uORF shows the same function as its overlapping small uORF, which is involved in translational repression and feedback controlled by polyamines. The presence of introns is necessary for the SAMDC up-regulation process when the internal spermidine level is low. Our results suggest that plants have evolved one network to adjust SAMDC activity through their 5′ leader sequences, through which transcriptional regulation is combined with an extensive posttranscriptional control circuit.
A Stilbene Synthase Gene (SbSTS1) Is Involved in Host and Nonhost Defense Responses in Sorghum
Authors: Yu Christine K.Y. , Springob Karin , Schmidt Jürgen , Nicholson Ralph L. , Chu Ivan K. , Yip Wing Kin , Lo Clive
Published: April 2005

A chalcone synthase (CHS)-like gene, SbCHS8, with high expressed sequence tag abundance in a pathogen-induced cDNA library, was identified previously in sorghum (Sorghum bicolor). Genomic Southern analysis revealed that SbCHS8 represents a single-copy gene. SbCHS8 expression was induced in sorghum mesocotyls following inoculation with Cochliobolus heterotrophus and Colletotrichum sublineolum, corresponding to nonhost and host defense responses, respectively. However, the induction was delayed by approximately 24 h when compared to the expression of at least one of the other SbCHS genes. In addition, SbCHS8 expression was not induced by light and did not occur in a tissue-specific manner. SbCHS8, together with SbCHS2, was overexpressed in transgenic Arabidopsis (Arabidopsis thaliana) tt4 (transparent testa) mutants defective in CHS activities. SbCHS2 rescued the ability of these mutants to accumulate flavonoids in seed coats and seedlings. In contrast, SbCHS8 failed to complement the mutation, suggesting that the encoded enzyme does not function as a CHS. To elucidate their biochemical functions, recombinant proteins were assayed with different phenylpropanoid-Coenzyme A esters. Flavanones and stilbenes were detected in the reaction products of SbCHS2 and SbCHS8, respectively. Taken together, our data demonstrated that SbCHS2 encodes a typical CHS that synthesizes naringenin chalcone, which is necessary for the formation of different flavonoid metabolites. On the other hand, SbCHS8, now retermed SbSTS1, encodes an enzyme with stilbene synthase activity, suggesting that sorghum accumulates stilbene-derived defense metabolites in addition to the well-characterized 3-deoxyanthocyanidin phytoalexins.
Morphological variations in the pre‐imaginal development of the ponerine antDiacamma ceylonense
Authors: Baratte Sébastien , Cobb Matthew , Deutsch Jean , Peeters Christian
Published: April 2005

In the present paper, the larval development of the queenless ponerine antDiacamma ceylonenseis studied. Four instars were identified on the basis of cuticular processes – tubercles and spinules – which show discontinuous variation during growth and provide precise and reliable external morphological criteria for instar discrimination. In the first three instars, the larva possesses a striking proboscis, which disappears between the third and fourth instars. Larval weight increased around 50‐fold in the 21 days of larval life between eclosion and pupation (mean weight for first instar = 0.37 mg; for fourth instar = 20 mg). In addition, the morphology of the gemmae, structures resembling vestigial wings in workers, is described in nymphae.
Aberrant methylations in cancer cells: Where do they come from?
Authors: Ushijima Toshikazu , Okochi‐Takada Eriko
Published: April 2005

Cancer epigenetics is rapidly moving into a translational phase, and knowledge on how aberrant DNA methylation is induced is becoming important. Aging, chronic inflammation, and viral infections are known to promote methylation of non‐core regions of promoter CpG islands (CGI). The non‐core methylation and ‘seeds of methylation’, scattered methylation in a CGI, are considered to serve as triggers for dense methylation of a promoter CGI, which permanently represses expression of its downstream gene. Decreased gene transcription is an important factor that promotes induction of dense methylation. The presence of the CGI methylator phenotype (CIMP), in which methylation of multiple CGI was observed, is under dispute. Some gastric cancer cell lines have increased rates of de novo methylation, and neuroblastoma cases with CIMP show qualitatively different prognosis from those without. This strongly supports the presence of CIMP, but it seems to contain multiple entities. Limited knowledge is available for epimutagens, the chemicals that induce DNA demethylation or methylation. We have developed an assay system to detect demethylating agents, and an assay system for methylating agents is necessary. Efforts in the field on how aberrant methylation is induced will lead to new cancer prevention, diagnostics, and therapeutics. (Cancer Sci 2005; 96: 206 –211)
Relationship‐based practice and reflective practice: holistic approaches to contemporary child care social work
Authors: Ruch Gillian
Published: April 2005

The renewed interest in relationship‐based practice can be understood in the child care social work context as a response to the call to re‐focus practice in this field. Relationship‐based practice challenges the prevailing trends which emphasize reductionist understandings of human behaviour and narrowly conceived bureaucratic responses to complex problems. In so doing practitioners engaged in relationship‐based practice need to be able to cope with the uniqueness of each individual's circumstances and the diverse knowledge sources required to make sense of complex, unpredictable problems. This paper argues that if relationship‐based practice is to become an established and effective approach to practice, practitioners need to develop their reflective capabilities. An outline of contemporary understandings of relationship‐based and reflective practice is offered and findings from doctoral research drawn on to identify how reflective practice complements relationship‐based practice. The product of this complementary relationship is enhanced understandings across four aspects of practice: the client, the professional self, the organizational context and the knowledges informing practice. The paper concludes by acknowledging the inextricably interconnected nature of relationship‐based and reflective practice and emphasizes the importance of practitioners being afforded opportunities to practise in relational and reflective ways.
Growth of Geobacter sulfurreducens under nutrient‐limiting conditions in continuous culture
Authors: Esteve‐Núñez Abraham , Rothermich Mary , Sharma Manju , Lovley Derek
Published: April 2005

A system for growing Geobacter sulfurreducens under anaerobic conditions in chemostats was developed in order to study the physiology of this organism under conditions that might more closely approximate those found in the subsurface than batch cultures. Geobacter sulfurreducens could be cultured under acetate‐limiting conditions with fumarate or Fe(III)‐citrate as the electron acceptor at growth rates between 0.04 and 0.09 h−1. The molar growth yield was threefold higher with fumarate as the electron acceptor than with Fe(III), despite the lower mid‐point potential of the fumarate/succinate redox couple. When growth was limited by availability of fumarate, high steady‐state concentrations were detected, suggesting that fumarate is unlikely to be an important electron acceptor in sedimentary environments. The half‐saturation constant, Ks, for acetate in Fe(III)‐grown cultures (10 µM) suggested that the growth of Geobacter species is likely to be acetate limited in most subsurface sediments, but that when millimolar quantities of acetate are added to the subsurface in order to promote the growth of Geobacter for bioremediation applications, this should be enough to overcome any acetate limitations. When the availability of electron acceptors, rather than acetate, limited growth, G. sulfurreducens was less efficient in incorporating acetate into biomass but had higher respiration rates, a desirable physiological characteristic when adding acetate to stimulate the activity of Geobacter species during in situ uranium bioremediation. These results demonstrate that the ability to study the growth of G. sulfurreducens under steady‐state conditions can provide insights into its physiological characteristics that have relevance for its activity in a diversity of sedimentary environments.
Diversity of Bacteria and Archaea associated with a carbonate‐rich metalliferous sediment sample from the Rainbow vent field on the Mid‐Atlantic Ridge
Authors: Nercessian Olivier , Fouquet Yves , Pierre Catherine , Prieur Daniel , Jeanthon Christian
Published: April 2005

Two sediment cores were collected in an inactive area of the deep‐sea hydrothermal vent field Rainbow (36°N on the Mid‐Atlantic Ridge). Metals and carbonates were abundant throughout the cores; calcite (CaCO3) was found throughout the cores while dolomite [CaMg(CO3)2] and siderite (FeCO3) were only found in deeper layers. Using polymerase chain reaction (PCR)‐amplified 16S rRNA gene sequence analysis, we examined the bacterial and archaeal diversity in a sediment layer that contained the three carbonates. The retrieved bacterial and archaeal sequences were new and less than 4% of the sequences exhibited 94% or more identity with that of cultured organisms. The analysis of the composition of the bacterial library  revealed  a  high  diversity  of  sequences.  Half of the bacterial clones was affiliated to the γ‐Proteobacteria. Most of them had environmental sequences retrieved from deep‐sea sediments as closest relatives, some of which being distantly related to free‐living and symbiotic sulfur‐oxidizers. Other sequences clustered in the α‐, δ‐ and ɛ‐Proteobacteria, the ‘Bacteroidetes’, the ‘Planctomycetes’, the ‘Nitrospirae’, the ‘Actinobacteria’, the ‘Chlorobi ’ and the ‘Verrumicrobia’. Based on clonal abundance and sequence comparisons, phylotype groups putatively involved in the oxydation of sulfur compounds appeared to dominate in the studied sample. The majority of the archaeal sequences clustered in an euryarchaeotic lineage recently identified in the walls of black smokers suggesting a possible thermophilic way of life of these uncultured microorganisms. Oxygen isotopic composition of siderite and dolomite indicated that they were formed at 67°C and 94°C respectively. Together with chemical and microbiological data, this suggested that hydrothermal fluids may have circulated through this sediment.
A cross‐sectional behavioral genetic analysis of task persistence in the transition to middle childhood
Authors: Deater‐Deckard Kirby , Petrill Stephen A. , Thompson Lee A. , DeThorne Laura S.
Published: April 2005

Task persistence, measured by a composite score of independent teacher, tester and observer reports, was examined using behavioral genetic analysis. Participants included 92 monozygotic and 137 same‐sex dizygotic twin pairs in Kindergarten or 1st grade (4.3 to 7.9 years old). Task persistence was widely distributed, higher among older children, positively associated with standardized tests of cognitive performance and achievement, and negatively associated with parents’, teachers’ and observers’ reports of behavioral problems. Cross‐sectional analysis indicated a strong developmental shift from shared environment variance among younger children to additive genetic variance in older children.
Localizing cortical sources of event‐related potentials in infants’ covert orienting
Authors: Richards John E.
Published: April 2005

This study used cortical source analysis to locate potential cortical sources of event‐related potentials (ERPs) during covert orienting in infants aged 14 and 20 weeks. The infants were tested in a spatial cueing procedure. The reaction time to localize the target showed response facilitation for valid trials relative to invalid or neutral trials. High‐density EEG (126 channels) was recorded during the task, and independent component analysis and equivalent current dipole analysis was used to estimate the cortical sources of the EEG during the task. There was a larger P1 ERP component on the valid trials than the other trials (P1 validity effect). The cortical source analysis suggested that this occurred due to activity in Brodmann's areas 18 and 19. A presaccadic ERP component occurred over the frontal scalp areas (−65 ms) and was larger to a target in a cued location than in uncued locations. A potential cortical source for this ERP component was the superior frontal gyrus on the inferior portion of the prefrontal cortex. Increases from 14 to 20 weeks in amplitude of the P1 validity effect and the presaccadic ERP could be modeled by an increase in activation in the corresponding cortical areas.
Forming a stable memory representation in the first year of life: why imitation is more than child's play
Authors: Lukowski Angela F. , Wiebe Sandra A. , Haight Jennifer C. , DeBoer Tracy , Nelson Charles A. , Bauer Patricia J.
Published: April 2005

Although 9‐month‐old infants are capable of retaining temporally ordered information over long delays, this ability is relatively fragile. It may be possible to facilitate long‐term retention by allowing infants to imitate event sequences immediately after their presentation. The effects of imitation on immediate and delayed recognition and on long‐term recall were investigated using event‐related potentials (ERPs) and elicited imitation, respectively. Mnemonic facilitation resulting from the opportunity to imitate was apparent using both assessments. ERP assessments at immediate and delayed recognition tests suggested that infants who were allowed to imitate had stronger memory representations of familiar stimuli relative to infants who only viewed the presentation of the events. In addition, infants who were allowed to imitate evidenced higher levels of ordered recall after 1 month relative to infants who only watched the experimenter's demonstration. Therefore, imitation proved to have beneficial effects on explicit memory in 9½‐month‐olds, providing evidence of its effectiveness as a tool to augment mnemonic capabilities in infancy.
PRINClPLES IN THE VALUATION OF HUMAN CAPITAL
Authors: Bowman Mary Jean
Published: April 2005

Human capital concepts and measures have been applied and misapplied to an increasing variety of economic problem areas, two of which are examined.

One of these is measurement of human capital gains and losses through migration. First requirements here are specification of the gaining or losing entities and of the relevant welfare functions. Alternatives in these respects are outlined. It is then argued that an appropriately adapted Fisherian present‐value assessment of human capital is normally the correct measure. Replacement costs are a legitimate substitute only for young migrants with little cumulated learning through experience and even then they have usually been fallaciously applied. Probability adjustments for migration and re‐migration are required in both cost and present‐value assessments of human capital effects of migration‐relevant policy alternatives, but the nature of those adjustments differs with the measurement approach used.

For longitudinal analysis of contributions of human capital to economic growth, all measures of human capital stocks are inappropriate. A first principle of such analysis is measurement of resource inputs as flows. A coordinate principle requires that disaggregation be carried as far as necessary to distinguish essentially homogeneous categories of labor inputs. Though a way of separating out the schooling versus on‐the‐job‐experience components of human capital is illustrated, it requires some strong assumptions. Splitting men into abstracted human capital components is better avoided in growth analysis. Furthermore, categorization of labor‐force sub‐groups could equally well provide the basis for rate‐of‐return assessments of marginal changes in the pace of investments in humans. Such assessments would incorporate the main elements of capital theory except valuation of the capital asset itself.

Ultimately, human resource measurements for use in major public policy decisions relating to either growth or migration (or both) must incorporate modifications or error components that allow for development phenomena that elude marginal assessments. Among developing countries especially, a consideration of educational diffusion processes and dynamic productivity scale effects, for example, could have critical measurement and policy implications.
INTERNATIONAL STUDIES OF FACTOR INPUTS AND TOTAL FACTOR PRODUCTIVITY: A BRIEF SURVEY
Authors: Nadiri M. Ishaq
Published: April 2005

This paper summarizes the results of several studies on total factor productivity of twenty‐five countries over the period 1950–1965. Some methodological issues which underlie the derivation and calculation of the familiar partial and total factor productivity indices are discussed. Though evidence on labor productivity for a large number of countries is presented and discussed, the main thrust of the discussion is in terms of the determinants of total factor productivity. The quantitative and qualitative contributions of labor and capital to growth of income are assessed with special attention to the contrasting patterns of these contributions among developed and developing economies. The problems of acceleration and retardation of the growth rate of some economies are considered and possible explanations are offered. Variations in the magnitude and sectoral distribution of the growth rates in several countries over this period are examined. Finally, areas for further research in comparative economic growth are suggested.
OUTPUT AND PRICES IN THE INTERNATIONAL COMPARISON PROJECT*
Authors: Kravis Irving B. , Kenessey Zoltan
Published: April 2005

In this paper we discuss a few of the problems that have been encountered in defining output and in comparing prices for the International Comparison Project (ICP). We report also on the way in which these problems are being met.

The ICP has for its purpose the establishment of a systematic set of procedures for making international comparisons of gross domestic product (GDP) and of the purchasing power of currencies. Substantive work on comparisons involving Colombia, the European Economic Community (EEC), Hungary, India, Japan, Kenya, the United Kingdom and the United States is also being carried on with the aid of the statistical services of the countries and of the EEC. It is hoped to expand the comparisons beyond these countries as rapidly as possible.
PROBLEMS OF INTERNATIONAL COMPARISONS OF NATIONAL ACCOUNTING AGGREGATES BETWEEN COUNTRIES WITH DIFFERENT ECONOMIC SYSTEMS
Authors: Jansen M. A.
Published: April 2005

This paper discusses a number of problems arising in comparisons of levels of national accounting aggregates between countries with different economic systems, notably between countries with market economies and countries with centrally planned economies. It considers problems arising from differences in the national accounting concepts used and problems arising from institutional differences, both of which are viewed as relating to the concepts on which the comparison should be based and the adjustment of national data to these concepts. The final section considers index number problems.
PROBLEMS OF COMPARISONS IN AFRICA WITH SPECIAL REGARD TO KENYA
Authors: Wood G. Donald
Published: April 2005

In order to obtain the information needed to include Kenya in an international comparison of income and purchasing power, it was necessary to collect some data to supplement the regularly collected statistics. Special collection was particularly important for capital goods prices and rural consumer goods prices. The remainder of the work involved using unpublished data available from the Kenyan Statistical Division, either to obtain additional detail required by the comparison, or to maintain international consistency in concept and estimating procedures.
THE INADEQUACY OF UNIT VALUE INDEXES AS PROXIES FOR CANADIAN INDUSTRIAL SELLING PRICE INDEXES*
Authors: Holmes R. A.
Published: April 2005

This paper considers the adequacy of unit value indexes as proxies for industrial selling price indexes in Canada, in light of the considerations raised in the Searle report for the United States (summarized elsewhere in this issue). Some 3,237 regressions are run using the industrial selling price index for a commodity group as the dependent variable and the corresponding unit value index as the independent variable. The unit value indexes perform poorly as predictors of the I.S.P.I.; the overall tendency is for the unit value index to overestimate changes in the I.S.P.I.; and to explain on average only about 30 percent of the total variance of the I.S.P.I.