bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of acrylate emulsion polymerization containing hydrophilic hydroxyl monomer in the presence of nano‐SiO2 particles
Authors: Yu Cai‐Li , Zhang Fa‐Ai , Zhu Xing‐Hua
Published: September 2008

Kinetics of acrylate emulsion polymerization containing hydrophilic hydroxyethyl methacrylate (HEMA) and acrylic acid (AA) in the presence of nano‐SiO2 were investigated. The influence of temperature, emulsifier level, hydroxyl monomer content and the level of nano‐SiO2 on monomer conversion, polymerization rate (Rp), and the particle size was studied. The results showed that the presence of nano‐SiO2 increased the Rp when the level was below 5% but decreased when the level was above 7.5%, the more levels, the more seriously. As the temperature and emulsifier levels increased, and the presence of hydroxyl monomer, the Rp increased. The active energy of the system was 142.01 kJ/mol and the relationship of Rp and the concentration of emulsifier (E) was Rp ∞ [E]0.38. The mean particle size increased, particle size distribution became broader as the nano‐SiO2 levels increased. Copyright © 2008 John Wiley & Sons, Ltd.
Effects of an evidence report and policies lifting reimbursement restrictions for acid suppressants: analysis of the Belgian national database
Authors: van Driel Mieke L. , Vander Stichele Robert , Elseviers Monique , De Sutter An , De Maeseneer Jan , Christiaens Thierry
Published: September 2008

Purpose

To explore the effect on prescribing of policies that lift reimbursement restrictions on selected H2‐antihistamines and proton pump inhibitors (PPI) and of practice recommendations.

Methods

Monthly claims based data for proton pump inhibitors (PPIs) and H2‐antihistamines were obtained from the national health insurance database (Farmanet 1997–2005). Two policies were issued. In March 2001 two H2‐antihistamines and in March 2003 two PPIs became available without restrictions. An evidence report was distributed in September 2004. Periods before and after implementation of the interventions were compared. Interrupted time series with segmented regression analysis was used to assess and compare time trends.

Results

The first policy resulted in an increase of volume (1.6 million DDDs; 95% CI 1.4–1.8 million; p < .001) and expenditure (€637 744; 95% CI 177 052–1 098 437; p = .026) for H2‐antihistamines, but consumption of PPIs continued to grow. After the second policy use of selected PPIs also increased (4.7 million DDDs increase; 95% CI 3.9–5.5 million; p < .001), but more than the desired shift toward selected PPIs. Although total expenditure stabilized at a lower level, there was no significant change of trend. Publication of the evidence report did not have any impact on prescribing.

Conclusions

Policies that lift reimbursement restrictions did not result in meaningful changes in utilization or cost saving. They may even have unintended effects. Collaboration between policymakers and guideline developers and linking policies to evidence‐based guidelines could be a more effective way to pursue cost‐containment and better quality of care. Copyright © 2008 John Wiley & Sons, Ltd.
A pilot study of the immediate effects of mirror feedback on sitting postural control in normal healthy adults
Authors: Watson Martin , Peck Matthew
Published: September 2008

Background and Purpose. The remediation of postural control problems is a common feature of many physiotherapy interventions. Provision of augmented visual feedback through use of mirror‐reflected body image is one means by which therapists can purportedly facilitate patients' postural correction abilities. Despite the historic place of this treatment modality within the physiotherapist's armamentarium, the strategy has however received very limited investigation. The aim of this study was to evaluate the extent to which availability of reflected body image influences the normal subjects' postural control abilities when in a sitting position. Method. A pilot investigation was undertaken, utilizing a sample of convenience comprising 18 healthy female subjects (mean age 20.8 years). All subjects underwent testing of their sitting postural control abilities in two separate conditions: with and without mirror feedback. A full length therapy mirror, as typically found in many rehabilitation departments, was used where appropriate to provide the reflected body image. Testing was carried out three times for each condition (six tests in total), obtaining average performance across three tests for each condition. Test order for each subject for the six tests was varied using a Latin square procedure to control for learning effect. Measurement of the subjects' postural control abilities was achieved by Balance Performance Monitor using a seat plate monitor and evaluating body sway path (mm). Postural control was challenged during testing by asking the subjects to maintain a standardized complex sitting position. Results. Group mean sway path with mirror feedback was lower than without: means 165.72 mm (standard deviation [SD] = 40.52 mm) versus 244.74 mm (SD = 68.48 mm). This suggested improved postural control ability when the subjects were able to view their reflected body image during testing. A related t test (t = 4.873, n = 18) showed differences between the two conditions to be statistically significant (p < 0.001), 95% confidence interval = 44.80 mm–113.23 mm. Conclusion. This relatively unsophisticated evaluation of mirror feedback nonetheless suggested a potential intervention effect. The precise mechanism(s) by which this strategy might effect changes in postural control ability, as well as the likely carryover of the effect and its replication in individuals with movement control problems, are all issues requiring further investigation. Nonetheless, these results provide provisional support for the notion that mirror feedback is a potentially useful strategy in the training of postural control. Copyright © 2008 John Wiley & Sons, Ltd.
New asperxanthone and asperbiphenyl from the marine fungus Aspergillus sp.
Authors: Wu Zu‐Jian , Ouyang Ming‐An , Tan Qing‐Wei
Published: September 2008

BACKGROUND: Marine fungi are of great importance as potential sources of agricultural pesticide leads. To continue work on new and biologically active metabolites from marine fungi, culture extracts of selected isolates were screened for inhibitory activity against tobacco mosaic virus (TMV), a typical member of the tobamovirus group of plant viruses.

RESULTS: A new difuranxanthone, asperxanthone (1), and a new biphenyl, asperbiphenyl (2), as well as seven known unsaturated fatty acid glycerol esters, were isolated from a selected marine fungus, identified as Aspergillus sp. (MF‐93), collected in the Quan‐Zhou Gulf. Two‐dimensional NMR methods and FAB‐MS established the structures of the new compounds. Among the compounds, 1 and 2 showed moderate activity (inhibitory rates 62.9 and 35.5% respectively) in inhibiting multiplication of TMV, higher than that of the other seven known lipids but much lower than that of the extract at the identical concentration of 0.2 mg mL−1.

CONCLUSION: Two new compounds, asperxanthone and asperbiphenyl, were identified as active components from Aspergillus sp. (MF‐93). Copyright © 2008 Society of Chemical Industry
Automatic sex detection of individuals of Ceratitis capitata by means of computer vision in a biofactory
Authors: Blasco Jose , Gómez‐Sanchís Juan , Gutierrez Abelardo , Chueca Patricia , Argilés Rafael , Moltó Enrique
Published: September 2008

BACKGROUND: The sterile insect technique (SIT) is acknowledged around the world as an effective method for biological pest control of Ceratitis capitata (Wiedemann). Sterile insects are produced in biofactories where one key issue is the selection of the progenitors that have to transmit specific genetic characteristics. Recombinant individuals must be removed as this colony is renewed. Nowadays, this task is performed manually, in a process that is extremely slow, painstaking and labour intensive, in which the sex of individuals must be identified. The paper explores the possibility of using vision sensors and pattern recognition algorithms for automated detection of recombinants.

RESULTS: An automatic system is proposed and tested to inspect individual specimens of C. capitata using machine vision. It includes a backlighting system and image processing algorithms for determining the sex of live flies in five high‐resolution images of each insect. The system is capable of identifying the sex of the flies by means of a program that analyses the contour of the abdomen, using fast Fourier transform features, to detect the presence of the ovipositor. Moreover, it can find the characteristic spatulate setae of males. Simulation tests with 1000 insects (5000 images) had 100% success in identifying male flies, with an error rate of 0.6% for female flies.

CONCLUSION: This work establishes the basis for building a machine for the automatic detection and removal of recombinant individuals in the selection of progenitors for biofactories, which would have huge benefits for SIT around the globe. Copyright © 2008 Society of Chemical Industry
Theory of excitons in carbon nanotubes
Authors: Ando Tsuneya , Uryu Seiji
Published: September 2008

A brief review is given on the electronic and optical properties of carbon nanotubes. The topics include an effective‐mass description of the electronic states, optical absorption and excitons, two‐photon absorption, excitons in metallic nanotubes, their fine structure and the Aharonov–Bohm effect, and exciton absorption for perpendicular polarization. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Narrowing of exciton linewidth of a quantum dot with increasing temperature
Authors: Bando Kazuki , Masumoto Yasuaki
Published: September 2008

Spectral narrowing of exciton luminescence at the elevated temperature was observed in a semiconductor quantum dot (QD). The Fourier spectroscopy was used for the study of decoherence processes of excitons in the single QD. High resolution spectra of the excitons were obtained from the Fourier transform of the decay profile of the exciton decoherence. We found that the exciton linewidth in the QD at low temperature was predominated by spectral diffusion due to carriers trapped at localized sites around the QD and the narrowing of the exciton line was induced by thermally activated escape processes of the carriers from the trap sites. The narrowing of the exciton line also indicates that the exciton decoherence in the semiconductor quantum dots is predominated by environmental fluctuation rather than the exciton‐phonon interaction at low temperature. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of non‐exponential decay of photogenerated carriers by recombination
Authors: Bando Takayoshi , Koshino Kazuki , Itoh Chihiro , Shinozuka Yuzo
Published: September 2008

Numerical simulation has been performed for the recombine dynamics of photogenerated carriers in a semiconductor surface. The simulation is based on the following three rules: (1) Just after photoexcitation, carriers (electrons and holes) are initially distributed at random on a two‐dimensional surface with equal densities. (2) Each carrier diffuses independently on the surface, obeying a random‐walk process with diffusion length σe and σh. (3) When the distance between an electron and a hole is smaller than the recombination radius r0, these carriers may disappear by recombination. Simulation on the survival probability P (t) has been performed for various values of parameters. Following results are obtained. P (t) at first decays exponentially with a shorter life time for larger σe and σh. But later, P (t) shows a longer tail for larger σe and σh. The longer tail can be fitted by a single stretched exponential function. All the qualitative results do not change if we use another model where the annihilation rate depends exponentially decaying function of the electron‐hole distance, assuming a tunnel recombination. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonuniform exciton localization in different GaAs quantum wells studied by spatially resolved cross‐sectional cathodoluminescence
Authors: Fujiwara K. , Jahn U. , Luna E. , Grahn H. T.
Published: September 2008

Excitonic radiative recombination in different GaAs quantum wells (QWs) is investigated by cross‐sectional cathodoluminescence (CL) spectroscopy with high spatial resolution. By measuring spectrally discriminated CL intensities originating from the various QWs as a function of excitation position, the exciton bands of the individual QWs can be mapped to see how the respective CL intensities are influenced by the excitation position along the growth direction. We find that nonuniform capture of nonequilibrium electron‐hole pairs by the QWs plays an important role for the exciton recombination, which strongly depends on the traversing pathway. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transient band‐bending in InP/InAs/InP core‐multishell nanowires
Authors: Goto Ken , Tomimoto Shinichi , Pal Bipul , Masumoto Yasuaki , Mohan Premila , Motohisa Junichi , Fukui Takashi
Published: September 2008

We report on the photoluminescence (PL) and time‐resolved PL (TR‐PL) spectroscopy of wurtzite InP/InAs/InP core‐multishell nanowires. Multiple peaks appeared in the PL spectra due to monolayer variation of InAs layers and each PL peak showed a blueshift with a cube‐root dependence on the excitation power. This blueshift results from the band‐bending in the type‐II band configuration. Fast decay caused by the relaxation of the band‐bending was observed at higher energy sides of the PL peaks in the TR‐PL measurement. The blueshift calculated by a triangular quantum well approximation in type‐II configuration was in good agreement with that observed in the experiment. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
4‐(dicyanomethylene)‐2‐methyl‐6‐(p‐dimethylaminostyryl)‐4H‐pyran (DCM)‐doping density dependence of luminescence spectra and white emission in polymer light‐emitting diodes
Authors: Inoue Akinori , Hosokawa Takeshi , Haishi Motoki , Ohtani Naoki
Published: September 2008

We fabricated white polymer light‐emitting diodes (PLEDs), in which the active region is doped with a low‐weight molecule. The host polymer material is Poly(9,9‐didodecyl‐fluorenyl‐2,7‐yleneethylnylene) (PFO), while the guest luminescent low‐weight‐molecule is 4‐(Dicyanomethylene)‐2‐methyl‐6‐(p‐dimethylaminostyryl)‐4H‐pyran (DCM). The photoluminescence (PL) and electroluminescence (EL) spectra strongly depend on DCM‐doping‐density. However, the most suitable DCM‐doping‐densities for white emissions in PL and EL are slightly different. This discrepancy is caused by the difference in excitation efficiencies. The photo‐excitation system for PL measurement is better than the current injection for generating carriers efficiently. Thus, the realization of the white EL signal requires the larger DCM‐doping‐density than that of the white PL signal. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanoscale organization of CD4 molecules of human T helper cell mapped by NSOM and quantum dots
Authors: Chen Jianan , Wu Yangzhe , Wang Chenxi , Cai Jiye
Published: September 2008

CD4 molecule, the surface marker of T helper cell, has been comfirmed to be the main cellular receptor for the human immunodeficiency viruses HIV‐1, HIV‐2 and SIV. Recent research demonstrated the importance of the spatial arrangement of CD4 on the cell membrane to its binding efficiency to virus. In this article, the combined near‐field scanning optical microscopy (NSOM) and quantum dots (QDs) fluorescent labeling technology were performed to investigate the nanoscale organization of CD4 molecules with a spatial resolution about 100 nm. Simultaneous topographic image of the T helper cell and fluorescent image of QDs have been directly gained by NSOM/QDs‐based system. Intensity‐ and size‐distribution histograms of the QDs fluorescent spots verify that approximately 80% of the CD4 molecules are organized in nanosized domains randomly distributed on the cell surface. Intensity‐size correlation analysis revealed heterogeneity in the molecular packing density of the domains. Our results also illustrated the combination of NSOM imaging and QDs labeling is an ultrasensitive, high‐resolution technique to probe nanoscale organization of molecules on the cell surface. SCANNING 30: 448–451, 2008. © 2008 Wiley Periodicals, Inc.
Next generation grids and wireless communication networks: towards a novel integrated approach
Authors: Fantacci Romano , Vanneschi Marco , Bertolli Carlo , Mencagli Gabriele , Tarchi Daniele
Published: September 2008

One of the most promising trends for next generation networks is to consider an integrated approach to the communication infrastructure and the processing layer. In particular, the introduction of broadband and reliable wireless networks allows the interaction of a huge number of devices all creating a single network. On the other hand, the grid paradigm is considered as one of the most promising approach for pervasive and dynamic applications. Aim of this paper is to present a novel integrated approach between grid paradigm and wireless networks by highlighting the main advantages of their cooperation. In particular, it will be shown here how a wireless heterogeneous network can be exploited for implementing a pervasive and dynamic grid (mobile grid) and, on the other hand, a mobile grid allows the optimization of the communication infrastructure. The integrated approach can be an effective method for solving applications, such as emergency management, where a huge amount of data derived from a wireless infrastructure needs to be processed efficiently and adaptively, and the traffic flow in the wide area wireless networks needs to be coordinated and optimized. Copyright © 2008 John Wiley & Sons, Ltd.
A power efficient solution to the large interference range problem in ad hoc networks
Authors: Lai Wei Kuang , Tsai Hsu‐Sheng , Li Chilin , Shieh Chin‐Shiuh
Published: September 2008

Due to the mismatch between the transmission range and interference‐vulnerable range, the reception at a receiving node in a wireless network could still be interfered by a sending node beyond the coverage of its clear‐to‐send (CTS). This is the so‐called large interference range problem. It is a common problem in real environments but overlooked by the standards and related studies. The large interference range problem could lead to transmission control protocol (TCP) instability and TCP unfairness, especially in case of multi‐hop transmission. There exist research works devoted to this issue. However, more power consumption was incurred at the same time. For a power‐efficient solution to this problem, a novel scheme, named power control interference avoidance (PCIA), is developed and presented in this article. The proposed scheme decouples control channel from data channel and use different power level in the transmission of control frames and data frames. By doing so, the large interference problem can be effectively avoided, while retaining a high level of power efficiency. The feasibility and effectiveness of the proposed scheme had been validated by an analytic study on a simplified model and a series of simulations. As revealed in the simulation results, the proposed PCIA scheme outperforms conservative CTS reply (CCR) and IEEE 802.11 in many aspects, including data corruption ratio and power efficiency. Copyright © 2008 John Wiley & Sons, Ltd.
FTIR and Raman Spectroscopy of Carbon Nanoparticles in SiO2, ZnO and NiO Matrices
Authors: Katumba G , Mwakikunga BW , Mothibinyane TR
Published: September 2008

Coatings of carbon nanoparticles dispersed in SiO2, ZnO and NiO matrices on aluminium substrates have been fabricated by a sol–gel technique. Spectrophotometry was used to determine the solar absorptance and the thermal emittance of the composite coatings with a view to apply these as selective solar absorber surfaces in solar thermal collectors. Cross-sectional high resolution transmission electron microscopy (X-HRTEM) was used to study the fine structure of the samples. Raman spectroscopy was used to estimate the grain size and crystallite size of the carbon clusters of the composite coatings. X-HRTEM studies revealed a nanometric grain size for all types of samples. The C–SiO2, C–ZnO and C–NiO coatings contained amorphous carbon nanoparticles embedded in nanocrystalline SiO2, ZnO and NiO matrices, respectively. Selected area electron diffraction (SAED) showed that a small amount of Ni grains of 30 nm diameter also existed in the NiO matrix. The thermal emittances of the samples were 10% for C–SiO2, 6% for the C–ZnO and 4% for the C–NiO samples. The solar absorptances were 95%, 71% and 84% for the C–SiO2, C–ZnO and C–NiO samples, respectively. Based on these results, C–NiO samples proved to have the best solar selectivity behaviour followed by the C–ZnO, and last were the C–SiO2samples. Raman spectroscopy studies revealed that both the C–ZnO and C–NiO samples have grain sizes for the carbon clusters in the range 55–62 nm and a crystallite size of 6 nm.
A short-term comparison of organicv. conventional agriculture in a silty loam soil using two organic amendments
Authors: HERENCIA J. F. , RUIZ J. C. , MELERO S. , GARCIA GALAVÍS P. A. , MAQUEDA C.
Published: September 2008

The transition from conventional to organic farming is accompanied by changes in soil chemical properties and processes that could affect soil fertility. The organic system is very complex and the present work carries out a short-term comparison of the effects of organic and conventional agriculture on the chemical properties of a silty loam soil (Xerofluvent) located in the Guadalquivir River Valley, Seville, Spain, through a succession of five crop cycles over a 3-year period. Crop rotation and varieties were compared in a conventional system using inorganic fertilizer and two organic systems using either plant compost or manure. At the end of the study, organic farming management resulted in higher soil organic carbon (OC), N and available P, K, Fe and Zn. The available Mn and especially Cu values did not show significant differences. In general, treatment with manure resulted in more rapid increases in soil nutrient values than did plant compost, which had an effect on several crop cycles later. The present study demonstrated that the use of organic composts results in an increase in OC and the storage of nutrients, which can provide long-term fertility benefits. Nevertheless, at least 2–3 years of organic management are necessary, depending on compost characteristics, to observe significant differences. Average crop yields were 23% lower in organic crops. Nevertheless, only two crops showed statistically significant differences.
The Science and Practice of Case Conceptualization
Authors: Kuyken Willem , Padesky Christine A. , Dudley Robert
Published: September 2008

Case conceptualization is a foundation of cognitive-behavioural therapy (CBT) because it describes and explains clients' presentations in ways that inform interventions. Yet the evidence base challenges the claimed benefits of case conceptualization. This paper reviews the rationale and evidence base for case conceptualization and outlines a new approach that uses the metaphor of a case conceptualization crucible in which a client's particular history, experience and strengths are synthesized with theory and research to produce an original and unique account of clients' presenting issues. The crucible metaphor illustrates three key defining principles of case conceptualization. First, heat drives chemical reactions in a crucible. In our model, collaborative empiricism between therapist and client provides the heat. Second, like the chemical reaction in a crucible, conceptualization develops over time. Typically, it begins at more descriptive levels, later a conceptualization incorporates explanatory elements and, if necessary, it develops further to include a longitudinal explanation of how pre-disposing and protective factors influence client issues. Finally, new substances formed in a crucible are dependent on the chemical characteristics of the materials put into it. Rather than simply look at client problems, our model incorporates client strengths at every stage of the conceptualization process to more effectively alleviate client distress and promote resilience.
What maternal factors influence the diet of 2-year-old children living in deprived areas? A cross-sectional survey
Authors: Crombie Iain K , Kiezebrink Kirsty , Irvine Linda , Wrieden Wendy L , Swanson Vivien , Power Kevin , Slane Peter W
Published: September 2008

Objective

To investigate the maternal factors associated with poor diet among disadvantaged children.

Design

Survey of 300 mothers of 2-year-old children from areas of high deprivation in Scotland (response rate 81 %). A diet quality score was derived from reported consumption of carbohydrates, protein, fruit and vegetables, dairy products and restriction of sugary fatty foods.

Results

Most children (85 %) were classified as having a poor quality diet (low diet quality score). Mothers’ general knowledge about healthy eating was high, but did not predict the quality of the children’s diet. Lower frequencies of food preparation and serving, such as cooking with raw ingredients, providing breakfast daily and the family eating together, were also associated with a poorer diet. Regression modelling identified five significant factors. An increased risk of a poor diet was associated with mothers being unlikely to restrict sweets (OR = 21·63, 95 % CI 2·70, 173·30) or finding it difficult to provide 2–3 portions of fruit daily (OR = 2·94, 95 % CI 1·09, 7·95). Concern that the child did not eat enough increased the risk of a poor diet (OR = 2·37, 95 % CI 1·09, 5·16). Believing a healthy diet would help the child eat more reduced the risk of having a poor diet (OR = 0·28, 95 % CI 0·11, 0·74), as did providing breakfast daily (OR = 0·22, 95 % CI 0·05, 0·99).

Conclusions

Interventions to improve children’s diet could promote more positive intentions about preparing and serving of foods, particularly of specific meals at which the family eats together. The benefits of these behaviours to the child (improved diet, weight control) should be emphasised.
Rupture process of four medium‐sized earthquakes that occurred in the Gulf of California
Authors: Rodríguez‐Lozoya Héctor E. , Quintanar Luis , Ortega Roberto , Rebollar Cecilio J. , Yagi Yuji
Published: September 2008

Four medium‐sized earthquakes (Mw Global CMT project 5.5, 5.6, 5.9, 6.3; hereinafter named Topolobampo, Angel de la Guarda, San Lorenzo, and Loreto earthquakes, respectively) located in the Gulf of California Extensional Province were studied to obtain their kinematic rupture processes. A network of broadband seismic stations located around the Gulf of California recorded the events (Network of Autonomously Recording Seismographs–Baja and Red Sísmica de Banda Ancha). Inversion of the seismic moment tensor and body waveform modeling were used to obtain the fault geometry and slip distribution on the fault plane, respectively. From these analyses, we obtained source depths of the order of 5.5 ± 0.5 km. We found also that the source rupture processes of the Topolobampo and Angel de la Guarda events have simple moment rate functions and source time durations of 5.0 ± 1.2 and 4.2 ± 1.2 s, respectively. The Topolobampo event was a right‐lateral strike‐slip event, and Angel de la Guarda was a normal event. The San Lorenzo and Loreto shocks show a rather complex rupture, with source time durations of 7.5 ± 1.2 and 9.0 ± 1.2 s, respectively. For these earthquakes, we tested the resolution of numerical results, performing an extra inversion with smoother waveforms. The new inversions do not show the separated patches of slip, as in the first analysis, but the slip distribution has an elongated shape not characteristic of simple events. We cannot therefore conclude rupture propagation for the San Lorenzo event, although the extent of the patch for the Loreto earthquake agrees with aftershock locations. Estimates of source time durations for these earthquakes are at the upper limit of the values found for earthquakes elsewhere. Directions of P axes are in the same order of magnitude as the maximum horizontal stress obtained for the so‐called Gulf of California stress province from borehole elongations, focal plane solutions, and fault slip data.
Global 3‐D model analysis of the seasonal cycle of atmospheric carbonyl sulfide: Implications for terrestrial vegetation uptake
Authors: Suntharalingam Parvadha , Kettle A. J. , Montzka S. M. , Jacob D. J.
Published: September 2008

We use a global 3‐D simulation of atmospheric carbonyl sulfide (COS) to interpret observations at a network of surface sites. We aim to identify the primary factors underlying observed seasonal variations and to constrain COS uptake by terrestrial vegetation. Model simulations are based on a recent estimate of global COS fluxes, with closure between sources and sinks. We find that the dominant influences on seasonal variation of COS are terrestrial vegetation uptake in the northern extratropics, and ocean fluxes in the southern extratropics. Simulations underestimate the amplitude of the observed seasonal cycle in the northern hemisphere, particularly at terrestrial sites, indicating that COS uptake by terrestrial vegetation has been underestimated in recent budgets. Fitting the observed seasonal variation at northern hemisphere sites in the model requires a doubling of the global vegetation sink to ∼490 Gg S y−1, while fitting the southern hemisphere data suggests a reduction of ∼50 Gg S y−1 in the southern extratropical ocean source. Balancing these changes in COS fluxes requires an additional source (∼235 Gg S y−1, equivalent to 40% of identified sources) missing from present budget estimates. Discrepancies between annual mean observations and simulated concentrations, derived from our best estimates of seasonal fluxes, are largest in the tropics, suggesting an underestimate of COS sources at these latitudes.
Unanticipated consequences of ocean acidification: A noisier ocean at lower pH
Authors: Hester Keith C. , Peltzer Edward T. , Kirkwood William J. , Brewer Peter G.
Published: September 2008

We show that ocean acidification from fossil fuel CO2 invasion and reduced ventilation will result in significant decreases in ocean sound absorption for frequencies lower than about 10 kHz. This effect is due to known pH‐dependent chemical relaxations in the B(OH)3/B(OH)4− and HCO3−/CO32− systems. The scale of surface ocean pH change today from the +105 ppmv change in atmospheric CO2 is about −0.12 pH units, resulting in frequency dependant decreases in sound absorption (α = dB/km) exceeding 12%. Under reasonable projections of future fossil fuel CO2 emissions and other sources a pH change of 0.3 units or more can be anticipated by mid‐century, resulting in a decrease in α by almost 40%. Ambient noise levels in the ocean within the auditory range critical for environmental, military, and economic interests are set to increase significantly due to the combined effects of decreased absorption and increasing sources from mankind's activities.
Evolution of the 2007–2008 Arctic sea ice cover and prospects for a new record in 2008
Authors: Drobot Sheldon , Stroeve Julienne , Maslanik James , Emery William , Fowler Charles , Kay Jennifer
Published: September 2008

The record Arctic sea ice minimum in 2007 has heightened debate on whether the Arctic Ocean has reached a tipping point, leading to a rapid transition towards a seasonal ice cover. Here, we review the 2007–2008 winter and spring ice and atmosphere conditions and assess how likely another record minimum is in summer 2008. At the end of June, 67% of the Arctic Ocean was covered by younger‐than‐average ice and only 5% was covered by older than‐average‐ice. Using a simple estimate based on ice survival rates, a new record low is reached in 2008 in 24 of 25 cases. With a more complex linear regression model, we suggest the September sea ice extent will be 4.40 million square kilometers, with a 40% chance that 2008 will set a new record low Arctic ice minimum.
Retrieval of air temperature profiles in the Venusian mesosphere from VIRTIS‐M data: Description and validation of algorithms
Authors: Grassi Davide , Drossart P. , Piccioni G. , Ignatiev N. I. , Zasova L. V. , Adriani A. , Moriconi M. L. , Irwin P. G. J. , Negrão A. , Migliorini A.
Published: September 2008

We present here methods developed for the retrieval of air temperature profiles in the Venusian mesosphere from the absolute radiances measured by the Visual and Infrared Thermal Imaging Spectrometer (VIRTIS) on board the Venus Express satellite. The infrared M channel of the instrument acquires multispectral images between 1000 and 5000 nm. In nighttime measurements, radiance in the range 3800–5000 nm is dominated by the thermal emission and absorption by the clouds and carbon dioxide. Since the latter is the main atmospheric component, it is possible to exploit the strong variability of its opacity in this spectral range, as resolved by the instrument, to reconstruct the vertical air temperature profile as a function of pressure. In this context we decided to adopt the Twomey et al. (1977) relaxation scheme. The resulting code was extensively tested on a set of simulated VIRTIS‐M data. Comparison of the known input conditions with the results of analysis code allowed us to evaluate the systematic and random errors affecting the retrievals procedures on a statistical basis. The code returns the vertical air temperature profile with an uncertainty of less than 1 K in the region between 70 and 7 mbar (66 and 77 km above the reference surface) and less than 4 K throughout the entire range 100–0.1 mbar (64–95 km). Finally, we present the first examples of the code applied to actual measured Venusian data, demonstrating its capability to achieve a satisfactory modeling of the observations and provide physically reasonable results.
Enhanced oscillator strength of interband transitions in coupled Ge∕Si quantum dots
Authors: Yakimov A. I. , Bloshsin A. A. , Dvurechenskii A. V.
Published: September 2008

We report a calculation of oscillator strength for the Δ1−Γ25′ interband transition in two vertically coupled pyramidal Ge quantum dots embedded in Si. A six-band k⋅p formalism was used to study the Γ25′ hole states, and a single-band approach was used to obtain the Δ1 electron state interacting with the hole. The elastic strain due to the lattice mismatch between Ge and Si was included into the problem via the Bir–Pikus Hamiltonian. We find that when two dots are brought closely together, the oscillator strength may enlarge by a factor of about 2 as compared to the single-dot system.
Hardening of the ferroelectric soft mode in SrTiO3 thin films
Authors: Katayama Ikufumi , Shimosato Hiroshi , Rana Dhanvir Singh , Kawayama Iwao , Tonouchi Masayoshi , Ashida Masaaki
Published: September 2008

We have studied the origin of soft-mode hardening in SrTiO3 thin films using broadband terahertz time-domain spectroscopy. We measured the dielectric dispersions in the terahertz region of as-deposited, O2 annealed, and high-temperature annealed SrTiO3 thin films deposited on MgO and La0.3Sr0.7Al0.65Ta0.35O3 substrates. The results show that the ferroelectric soft mode softens dramatically by the high-temperature annealing. We also measure x-ray diffractions and atomic force microscope images and conclude that the hardening of the ferroelectric soft mode in the thin films is determined by the grain size of each crystalline domain which is enlarged by the high-temperature annealing due to remelting.
Electron trapping in pentacene based p- and n-type organic field-effect transistors
Authors: Siol Christopher , Melzer Christian , von Seggern Heinz
Published: September 2008

We report on electron trapping in the channel of pentacene field-effect transistors due to electron injection over large energy barriers. Using scanning Kelvin-probe microscopy, one observes temporary and permanent electron trapping in the transistor channel for both n- and p-type organic field-effect transistors driven in ambipolar mode, proving the ability of electrons to be injected from Au contacts into pentacene despite a large energy barrier. The trapped negative charge carriers are determined to be the origin of hysteresis in n-type devices and appear to be the source of threshold voltage shifts for p-type transistors.
Al-based metallic glass composites containing fcc Pb-rich crystalline spheres
Authors: He Jie , Li Haiquan , Zhao Jiuzhou , Dai Chunli
Published: September 2008

Liquid immiscible systems present a unique opportunity in designing composites with sphere-dispersed microstructure. The authors report here phase formation of a multicomponent Al82.87Pb2.5Ni4.88Y7.8Co1.95 alloy upon melt spinning. The alloy undergoes liquid-liquid phase transformation in the liquid immiscibility gap and subsequently solidifies into Pb-rich crystalline phase and Al-rich amorphous phase. The Pb-rich phase with sphere shape is dispersed in the Al-based metallic glass matrix. The average diameter of the Pb-rich spheres is ∼0.62 μm near the free side and ∼0.03 μm near the wheel side of the ribbon.
Electrical properties of Ta-doped SnO2 thin films epitaxially grown on TiO2 substrate
Authors: Toyosaki H. , Kawasaki M. , Tokura Y.
Published: September 2008

We report electrical properties of Ta-doped SnO2 (Sn1−xTaxO2) films epitaxially grown on (110) surfaces of rutile TiO2 single crystalline substrates by a pulsed laser deposition method. Due to the large in-plane lattice mismatches (3.0% along [1¯10] and 7.7% along [001]), the films had almost relaxed crystalline structure. With increasing x, electron density was systematically enhanced to undergo the insulator-metal transition between x=0.0004 and 0.004. Sn0.95Ta0.05O2 films exhibited the resistivity as low as 1.1×10−4 Ω cm that is comparable to the lowest value for an epitaxial In2O3 film doped with Sn.
High quality GaN-based Schottky barrier diodes
Authors: Lee K. H. , Chang S. J. , Chang P. C. , Wang Y. C. , Kuo C. H.
Published: September 2008

We report the fabrication of GaN-based Schottky barrier diodes with multi-MgxNy/GaN buffer. Compared to conventional devices with a low-temperature GaN buffer, we achieved a six orders of magnitude smaller leakage current. It was also found that effective Schottky barrier height is larger for the proposed device due to the reduction in surface defect density by using the multi-MgxNy/GaN buffer.
Thickness and the Koffka Ring Effect
Authors: Huang Abigail E , Hon Alice J , Altschuler Eric Lewin
Published: September 2008

Over seven decades ago Gestalt psychologist Kurt Koffka described a remarkable effect: when a contiguous gray ring is placed on a background half of one shade of gray, half of another, the ring appears homogeneous. However, if the ring is slightly divided, the two halves of the ring appear different shades of gray, the half of the ring on the darker background appearing lighter than the half of the ring on the lighter background. The Gestalt principle of continuity is used to explain this effect. We show that when the ring is made thinner it appears heterogeneous even when contiguous. We also illustrate this in the additional material with a colored background with more than two regions.
Kinetic regulation of coated vesicle secretion
Authors: Foret Lionel , Sens Pierre
Published: September 2008

The secretion of vesicles for intracellular transport often relies on the aggregation of specialized membrane-bound proteins into a coat able to curve cell membranes. The nucleation and growth of a protein coat is a kinetic process that competes with the energy-consuming turnover of coat components between the membrane and the cytosol. We propose a generic kinetic description of coat assembly and the formation of coated vesicles and discuss its implication to the dynamics of COP vesicles that traffic within the Golgi and with the endoplasmic reticulum. We show that stationary coats of fixed area emerge from the competition between coat growth and the recycling of coat components, in a fashion resembling the treadmilling of cytoskeletal filaments. We further show that the turnover of coat components allows for a highly sensitive switching mechanism between a quiescent and a vesicle producing membrane, upon a slowing down of the exchange kinetics. We claim that the existence of this switching behavior, also triggered by factors, such as the presence of cargo and variation of the membrane mechanical tension, allows for efficient regulation of vesicle secretion. We propose a model, supported by different experimental observations, in which vesiculation of secretory membranes is impaired by the energy-consuming desorption of coat proteins, until the presence of cargo or other factors triggers a dynamical switch into a vesicle producing state.
Distinct memories of odor intensity and quality in
Drosophila
Authors: Masek Pavel , Heisenberg Martin
Published: September 2008

Even in a simple Pavlovian memory task an animal may form several associations that can be independently assessed by the appropriate tests. Studying conditioned odor discrimination of the fruit fly
Drosophila melanogaster
we found that animals store quality and intensity of an odor as separate memory traces. The trace of odor intensity is short-lived, decaying in <3 h. Only the last intensity value is stored. In contrast to odor-quality memory, odor-intensity memory does not require the
rutabaga
-dependent cAMP signaling pathway. Flies rely on their memory of intensity in a narrow concentration range in which they can generalize intensity. Larger concentration differences they treat like different qualities. This study shows that the perceptual identity of an odor is based on at least three lines of processing in the brain: (
i
) a memory of odor quality, (
ii
) a memory of odor intensity, and (
iii
) a range of intensities (and qualities), in which the odor is generalized.
Positioning of autoimmune TCR-Ob.2F3 and TCR-Ob.3D1 on the MBP85–99/HLA-DR2 complex
Authors: Kato Zenichiro , Stern Joel N. H. , Nakamura Hironori K. , Kuwata Kazuo , Kondo Naomi , Strominger Jack L.
Published: September 2008

Since the first determination of structure of the HLA-A2 complex, >200 MHC/peptide structures have been recorded, whereas the available T cell receptor (TCR)/peptide/MHC complex structures now are <20. Among these structures, only six are TCR/peptide/MHC Class II (MHCII) structures. The most recent of these structures, obtained by using TCR-Ob.1A12 from a multiple sclerosis patient and the MBP85–99/HLA-DR2 complex, was very unusual in that the TCR was located near the N-terminal end of the peptide-binding cleft of the MHCII protein and had an orthogonal angle on the peptide/MHC complex. The unusual structure suggested the possibility of a disturbance of its signaling capability that could be related to autoimmunity. Here, homology modeling and a new simulation method developed for TCR/peptide/MHC docking have been used to examine the positioning of the complex of two additional TCRs obtained from the same patient (TCR-Ob.2F3 or TCR-Ob.3D1 with MBP85–99/HLA-DR2). The structures obtained by this simulation are compatible with available data on peptide specificity of the TCR epitope. All three TCRs from patient Ob including that from the previously determined crystal structure show a counterclockwise rotation. Two of them are located near the N terminus of the peptide-binding cleft, whereas the third is near the center. These data are compatible with the hypothesis that the rotation of the TCRs may alter the downstream signaling.
Yu-Rock in the 1980s: Between Urban and Rural
Authors: Pogačar Martin
Published: September 2008

Trivial though they may seem, popular culture and mass media actually present an important part of our quotidian and play significant roles in defining dimensions of our environments—past and present, internal as well as external. Mediatized images of bygone times and faraway places invade and transfix the physical geographies of the living environment; invade and transfix, extremely subtly, symbolic geographies of every single human being. Despite the fictitious nature and perceived triviality of cinema, literature and music, they feature as modes of representation and communication for a wide array of topics and issues that present an important part of human existence. Therefore, archaeology of popular culture might be a useful complement to other past-reconstructing practices.
Conceptions of assessment: trainee teachers' practice and values
Authors: Winterbottom Mark , Brindley Sue , Taber Keith S. , Fisher Linda G. , Finney John , Riga Fran
Published: September 2008

This study examines the values and practice in relation to assessment of a sample of 220 trainee teachers studying for a Postgraduate Certificate in Education, an initial teacher training and education (ITET) course, at the University of Cambridge, UK. The survey instrument was drawn from James and Pedder (2006), and was composed of questionnaire items that sought to elicit how trainees valued different classroom assessment practices, and the extent to which their own teaching complied with such values. The study draws additionally on the findings of James and Pedder (2006) to compare and contrast results with those for qualified teachers. Item and factor analyses revealed three dimensions that underpin trainees' classroom practice and values (promoting learning autonomy, performance orientation, making learning explicit). Values‐practice gaps were greatest on promoting learning autonomy and performance orientation. Trainees valued practices associated with the former more than they implemented them in their teaching, while they implemented practices associated with the latter more than predicted by their values. Values‐practice gaps suggested that trainees were constrained from implementing their values to a greater extent than qualified teachers, particularly with respect to these two factors.
Injecting risk behaviour and related harm among men who use performance‐ and image‐enhancing drugs
Authors: LARANCE BRIONY , DEGENHARDT LOUISA , COPELAND JAN , DILLON PAUL
Published: September 2008

Introduction and Aims. Performance‐ and image‐enhancing drugs have the potential to be a significant public health issue. Detailed data on PIEDs injection are difficult to obtain because of the illicit and unsupervised way in which many PIEDs are used, and the hidden nature of the group. Our study examines the patterns of use, risk behaviours and related harm associated with PIEDs injection. We also report the ways in which PIEDs users currently seek injecting equipment and harm‐reduction advice. Design and Method. Data were obtained via a structured questionnaire administered in face‐to‐face interviews with 60 men who used PIEDs (primarily anabolic androgenic steroids) for non‐medical purposes. Results. Although the rates of needle sharing were low (5%), the men more frequently reported re‐use of needles/equipment, injecting from a shared container (bladders, vials, etc.), injecting other illicit drugs, injecting insulin and targeting small muscle groups. Self‐reports of being hepatitis C antibody positive were associated with lifetime use of heroin and injection of other illicit drugs. All HIV positive participants were gay/bisexual men. Participants reported a range of other injection‐related injuries and diseases such as fevers, scarring and abscesses. ‘Risky’ injectors (38% of participants) were more likely to initiate PIEDs use at a younger age, use PIEDs in a larger number of cycles per year and report involvement in a violent/aggressive incident than ‘low risk’ injectors and report involvement in a violent/aggressive incident than ‘low risk’ injectors. Participants mainly reported seeking information about PIEDs from internet sites (62%) and friends (55%). Conclusions. An over‐reliance on personal networks and internet forums limits this groups' access to objective harm reduction advice and primary care services. Targeted, PIEDs‐specific interventions are needed.