bluuebunny/crossref_metadata_2025 huggingface dataset:
On design of air-core Ethernet transformers
Authors: Bowen D. , Mayergoyz I. , Krafft C. , Kroop D. , Beyaz M.
Published: February 2009

The air-core designs of Ethernet transformers in which the reduction of winding magnetic coupling is compensated by increasing the cross-winding capacitance coupling are discussed. The theoretical analysis that accounts for the distributed nature of the cross-winding capacitance is presented. It is demonstrated that the capacitive cross-winding coupling may result in desirable transfer characteristics of air-core transformers that are similar to those of ferrite core Ethernet transformers.
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Mössbauer study of first-order phase transition in LaVO3
Authors: Yoon Sunghyun
Published: February 2009

Nature of phase transition in polycrystalline LaVO3 has been studied using Mössbauer spectroscopy with 1% F57e doped sample. Magnetic susceptibility of sample taken upon both field cooled and zero-field cooled exhibited a peak at TN∼137 K, indicative of antiferromagnetic-paramagnetic phase transition. Up to 110 K, Mössbauer spectra were well-resolved sextets. However, abrupt first-order collapse in the hyperfine pattern took place in the narrow temperature range of 110–115 K, which is much below the transition temperature TN deduced from the magnetic measurement. Spectral lines became broader with increasing temperature until a pronounced central singlet appeared near 115 K, suggesting the appearance of relaxation effect. The first-order-like collapse in hyperfine magnetic spectra was found to originate from the fast relaxation due to dynamic magnetostrictive deformation setting in much below TN.
Soft spin modes and magnetic transitions in trilayered nanodisks in the vortex state
Authors: Montoncello F. , Giovannini L. , Nizzoli F.
Published: February 2009

We present calculations of spin dynamics of a trilayered cylindrical nanodot with circular cross section, which is made of two permalloy disks with the same diameter (200 nm) and different thicknesses (20 and 10 nm), separated by a nonmagetic 10 nm thick spacer. The calculations are performed within the framework of the dynamical matrix method. Due to the different layer thicknesses, the ground state of this system at zero applied field is the vortex configuration in both layers. This system is the ideal one to investigate the dynamics of vortex modes in multilayered dots: we calculate doublets of gyrotropic, radial, and azimuthal modes, which are in phase and out-of-phase in the two layers. The dependence of these modes on vortex polarity and node number is investigated. The modes are studied as a function of a tangential magnetic field. The transition to the saturated state occurs at different critical fields for the two layers. In the proximity of these critical points, the magnetization discontinuities are related to the occurrence of soft modes.
Collective magnetic behaviors of Fe–Ag nanostructured thin films above the percolation limit
Authors: Alonso J. , Fdez-Gubieda M. L. , Fernández Barquín L. , de Pedro I. , Barandiarán J. M. , Orue I. , Svalov A. , Sarmiento G.
Published: February 2009

The magnetic behavior of sputtered and pulsed laser deposited (PLD) FexAg100−x thin films with 27≤x≤55 has been studied by means of ac and dc magnetic measurements. Sputtered samples present a continuous decrease in the magnetization, down to 310 K for x=30, where a magnetic transition into a superparamagnetic state with the presence of dipolar interactions is observed. The ac susceptibility measurements indicate that this transition resembles that of three dimensional glassy systems. Sputtered samples with higher concentration of Fe present a similar but slower thermal evolution of magnetization. PLD samples with x≥50 show a Curie–Weiss-type transition above ∼200 K triggered by direct exchange interactions. As the temperature decreases, the system behaves like a ferromagnet and below ∼75 K, a transition into a cluster-glass state appears. As the composition decreases, these phenomena vanish.
Effects of hydrogen impurities on MnxSi1−x semiconductors
Authors: Wang X. L. , Ni M. Y. , Zeng Z. , Lin H. Q.
Published: February 2009

In the present work, we have chosen different configurations to perform relaxations to determine the ground states of hydrogen doping in MnxSi1−x, respectively. Our results show that hydrogen impurity intends to bond strongly to Mn ion in MnxSi1−x. After introducing hydrogen, the phase transfer occurs from a half metallic one to a metallic case, and the magnetic moment of Mn ion is reduced. In MnxSi1−x, Mn ions exhibit a strong short-range antiferromagnetic and long-range ferromagnetic interaction. However, with the hydrogen doping, the exchange interactions of Mn ions oscillate between antiferromagnetic coupling and ferromagnetic coupling as a function of the distances between Mn ions. Hydrogen significantly influences the properties of MnxSi1−x.
CCSD(T) study of the far-infrared spectrum of ethyl methyl ether
Authors: Senent M. L. , Ruiz R. , Villa M. , Domínguez-Gómez R.
Published: February 2009

Band positions and intensities for the far-infrared bands of ethyl methyl ether are variationally determined from a three-dimensional (3D) potential energy surface calculated with CCSD(T)/cc-pVTZ theory. For this purpose, the energies of 181 selected geometries computed optimizing 3n−9 parameters are fitted to a 3D Fourier series depending on three torsional coordinates. The zero point vibrational energy correction and the search of a correct definition of the methyl torsional coordinate are taken into consideration for obtaining very accurate frequencies. In addition, second order perturbation theory is applied on the two molecular conformers, trans and cis-gauche, in order to test the validity of the 3D model. Consequently, a new assignment of previous experimental bands, congruent with the new ab initio results, is proposed. For the most stable trans-conformer, the ν30, ν29, and ν28 fundamental transitions, computed at 115.3, 206.5, and 255.2 cm−1, are correlated with the observed bands at 115.4, 202, and 248 cm−1. For the cis-gauche the three band positions are computed at 91.0, 192.5, and 243.8 cm−1. Calculations on the −d3 isotopomer confirm our assignment. Intensities are determined at room temperature and at 10 K. Structural parameters, potential energy barriers, anharmonic frequencies for the 3n−9 neglected modes, and rotational parameters (rotational and centrifugal distortion constants), are also provided.
Growth and photoluminescence characteristics of ZnO tripods
Authors: Mandal S. , Dhar A. , Ray S. K.
Published: February 2009

Hexagonal and preferentially oriented three-dimensional ZnO tripods have been grown on p-Si [100] substrates by a simple vapor-solid technique without using any catalysts. The tripodal-core growth route involves the formation of a hexagonal disk with [0002] larger surfaces. The tripods show irreversible shape transformation to tetrapods at higher temperature and prolonged growth time. Temperature-dependent photoluminescence characteristics of ZnO tripods have been investigated in the range from 10 to 300 K. Multiple LO phonon-assisted emissions associated with both bound and free excitons are observed for tripods, the origin of which have been explained by Permogorov’s theory for II–VI semiconductors.
Comment on “Particle concentration and tube size dependence of viscosities of Al2O3—water nanofluids flowing through micro- and minitubes” [Appl. Phys. Lett. 91, 243112 (2007)]
Authors: Ayela F. , Chevalier J.
Published: February 2009

In a recent letter, Jang et al. [Appl. Phys. Lett. 91, 243112 (2007)] reported an anomalous viscosity enhancement for very dilute nanofluids (0.02–0.3 vol %). They claim that the size of nanoparticles relative to the tube size has a profound influence on the viscosity of the nanofluids flowing through micro- and minichannels in a fully developed laminar flow. The authors used Al2O3 nanoparticles with a mean diameter of 30±5 nm dispersed in water. We believe that their interpretation of these experiments is questionable because they have underestimated the importance of experimental uncertainties. A conventional explanation of their results can be drawn from simple hypothesis.
Supercurrent decay in nano-superconducting quantum interference devices for intrinsic magnetic flux resolution
Authors: Granata C. , Vettoliere A. , Russo R. , Esposito E. , Russo M. , Ruggiero B.
Published: February 2009

Supercurrent decay measurements of nano-superconducting quantum interference devices (SQUIDs) based on niobium constrictions (Dayem bridges) are reported. Such measurements provide useful information for applications that employ the SQUID as a trigger where the sensor works on the zero voltage state. The nanodevice consists of a niobium thin film (30 nm thick) ring with a hole side length of 200 nm including two Dayem bridges of 120×200 nm2. The measurements of the switching current distribution from the zero voltage state and the related escape rate, as function of the bias current, have been performed by a low noise fly time technique. The experimental data have shown an intrinsic current fluctuation less than 0.2% of the critical current at liquid helium temperature, corresponding to an intrinsic sensor magnetic flux resolution of a few mΦ0. The theoretical predictions based on the thermal escape process theory in the moderately damping limit are in a reasonable agreement with the experimental data.
Strain measured in a silicon-on-insulator, complementary metal-oxide-semiconductor device channel induced by embedded silicon-carbon source/drain regions
Authors: Murray Conal E. , Ren Z. , Ying A. , Polvino S. M. , Noyan I. C. , Cai Z.
Published: February 2009

The strain imparted to 60 nm wide, silicon-on-insulator (SOI) channel regions by heteroepitaxially deposited, embedded silicon-carbon (e-SiC) features was measured using x-ray microbeam diffraction, representing one of the first direct measurements of the lattice parameter conducted in situ in an SOI device channel. Comparisons of closed-form, analytical modeling to the measured, depth-averaged strain distributions show close correspondence for the e-SiC features but 95% of the predicted strain in the SOI channel. Mechanical constraint due to the overlying gate and the contribution of SOI underneath the e-SiC in the diffracting volume to the measurements can explain this difference.
Local stress engineering of magnetic anisotropy in soft magnetic thin films
Authors: Martin Norbert , McCord Jeffrey , Gerber Andreas , Strache Thomas , Gemming Thomas , Mönch Ingolf , Farag Nayel , Schäfer Rudolf , Fassbender Jürgen , Quandt Eckhard , Schultz Ludwig
Published: February 2009

The magnetic anisotropy of amorphous thin films was modified laterally by masked ion irradiation without alteration of the intrinsic magnetic properties. The changes were introduced by local ion implantation in a protection layer, causing additional stress-induced magnetic anisotropy in the magnetostrictive layer. The underlying local variation in magnetic anisotropy was modeled and confirmed experimentally. The described method, relying purely on magnetoelastics, introduces a new path to the alteration of magnetic properties subsequent to magnetic film preparation. With the use of the resulting artificial magnetization patterns, it is possible to tailor the ferromagnetic thin film structure used in magnetoelectronic applications.
Smith–Purcell frequency multiplier with synchronization of radiation from a wide electron beam
Authors: Bratman V. L. , Fedotov A. E. , Makhalov P. B. , Rusin F. S.
Published: February 2009

An orotronlike feedback can provide a significant increase in the selectivity and power of frequency-multiplied Smith–Purcell radiation of the electron bunches formed in the course of self-excitation of a grating surface eigenmode. This method looks promising for efficient terahertz generation from both weakly and mildly relativistic electron beams.
Structural tuning of color chromaticity through nonradiative energy transfer by interspacing CdTe nanocrystal monolayers
Authors: Cicek Neslihan , Nizamoglu Sedat , Ozel Tuncay , Mutlugun Evren , Karatay Durmus Ugur , Lesnyak Vladimir , Otto Tobias , Gaponik Nikolai , Eychmüller Alexander , Demir Hilmi Volkan
Published: February 2009

We proposed and demonstrated architectural tuning of color chromaticity by controlling photoluminescence decay kinetics through nonradiative Förster resonance energy transfer in the heterostructure of layer-by-layer spaced CdTe nanocrystal (NC) solids. We achieved highly sensitive tuning by precisely adjusting the energy transfer efficiency from donor NCs to acceptor NCs via controlling interspacing between them at the nanoscale. By modifying decay lifetimes of donors from 12.05 to 2.96 ns and acceptors from 3.68 to 14.57 ns, we fine-tuned chromaticity coordinates from (x,y)=(0.575,0.424) to (0.632, 0.367). This structural adjustment enabled a postsynthesis color tuning capability, alternative or additive to using the size, shape, and composition of NCs.
Different Atmospheres: Of Sloterdijk, China, and Site
Authors: Thrift Nigel
Published: February 2009

This paper begins with an appreciation and critique of the remarkable work of Peter Sloterdijk which makes it possible to open up a number of issues concerning philosophy and its relation to the social sciences and humanities, most particularly concerning the role of evidence and the pervasiveness of Eurocentrism. In particular, the paper argues that it is possible to think of different ways of raising the spectre of space which are as plausible as the account provided by Sloterdijk's spatial philosophy/philosophy of space. Navigating by the compass of classical Chinese civilisation, I proceed to sketch out a different diagnosis from that of Sloterdijk of how space is being materialised in contemporary Euro-American cultures. Drawing on logographic traditions of writing the world, I argue that, rather than describing what is now being produced by capitalism and other actors as a warehoused world full of lost souls, it is possible to think of different means of describing how the future is being scripted.
Uncatalyzed Knoevenagel Condensation in PEG-600 at Room Temperature
Authors: Bandgar Babasaheb P. , Korbad Balaji L. , Patil Sachin A. , Bandgar Sunita B. , Chavan Hemant V. , Hote Baliram S.
Published: February 2009

A rapid, efficient, and ecofriendly protocol has been developed for the Knoevenagel condensation of active methylene compounds with aromatic, aliphatic, conjugated and heteroaromatic aldehydes in polyethylene glycol-600 (PEG-600) with good to excellent yields.
Synthesis and Characterization of Rutile and Anatase in Air- and Water-Stable Ionic Liquids with and without Isopropanol as a Cosolvent
Authors: Al Zoubi Mohammad , Farag Hala K. , Endres Frank
Published: February 2009

Nanocrystalline TiO2 with pure rutile and pure anatase phases was prepared at moderate reaction temperatures by hydrolysis of TiCl4 in different air- and water-stable ionic liquids with the same anion ([Py1,4]Tf2N, [EMIM]Tf2N, and [P14,6,6,6]Tf2N), in isopropanol and in cosolvent of ionic liquid/isopropanol under different reaction conditions. The type of cation in the ionic liquid influences the morphology of the rutile phase: cone-like morphology was obtained in the case of [Py1,4]+ and [P14,6,6,6]+ ions and wormhole-like in the case of [EMIM]+. In the case of anatase, no significant effect was found. The influence of various reaction conditions like acidity of solution, solvent type, precursor type, and precursor concentration on the phase formation and morphology of titania were investigated.
A High Relaxivity Magnetic Resonance Imaging Contrast Agent Targeted to Serum Albumin
Authors: Dumas Stéphane , Troughton Jeffrey S. , Cloutier Normand J. , Chasse Jaclyn M. , McMurry Thomas J. , Caravan Peter
Published: February 2009

EP-647 is a serum albumin-targeted magnetic resonance imaging contrast agent comprising a GdDTPA (DTPA, diethylenetriaminepentaacetate) chelate for magnetic resonance signal generation linked via a phosphodiester to a substituted biphenyl for albumin targeting. Albumin binding and relaxivity are higher than the benchmark magnetic resonance angiographic agent MS-325. EP-647 binds primarily to a unique site on serum albumin that is different from the MS-325 site and the binding sites of other drugs.
The Design of Gold-Based, Mitochondria-Targeted Chemotherapeutics
Authors: Berners-Price Susan J. , Filipovska Aleksandra
Published: February 2009

Recent developments in understanding the central place of mitochondria as regulators of programmed cell death have stimulated enormous interest in using them as targets for cancer chemotherapy. To overcome drug resistance and the lack of selectivity of cancer drugs in differentiating between normal and tumour cells, many strategies have been described in recent literature, including the use of delocalized lipophilic cations that selectively accumulate in tumour-cell mitochondria. Thioredoxin reductase, an enzyme involved in redox regulation and cell growth, has also emerged recently as an attractive drug target. Here we discuss the rationale for the design of lipophilic, cationic Au(i) phosphine complexes that are targeted to mitochondria of tumour cells and have potent and selective anticancer activity for cancer cells but not for normal cells. Our discovery that the thioredoxin system may be a critical target responsible for the selective toxicity provides a new strategy in the development of mitochondria-targeted chemotherapeutics.
'Clean' or 'Dirty' – Just How Selective Do Drugs Need To Be?
Authors: Abbenante Giovanni , Reid Robert C. , Fairlie David P.
Published: February 2009

Chemotherapy has developed largely on the basis of searching for chemicals with selective toxicity, targeting a specific step or receptor in a disease process without negatively impacting on normal physiology. The desire for ‘clean’ drugs that act on a single target and thus avoid side effects has led to ever-increasing timeframes for introducing new drugs to humans. This has led to reappraisal of how selective drugs need to be. Examples here of compounds from common drug classes (kinase inhibitors, protease inhibitors, G protein coupled receptors ligands, non-steroidal anti-inflammatory drugs, statins, antibodies) highlight current debate on the merits of target selectivity versus target promiscuity in the development of drugs for inflammation, cancer, cardiovascular, central nervous system and infectious diseases.
Shoot δ15N gives a better indication than ion concentration or Δ13C of genotypic differences in the response of durum wheat to salinity
Authors: Yousfi Salima , Serret Maria Dolores , Araus José Luis
Published: February 2009

We compared the performance of different physiological traits that reveal genotypic variations in tolerance to salinity in durum wheat. A set of 114 genotypes was grown in hydroponics for over 3 months. Three conditions: control, moderate (12 dS m−1) and severe (17 dS m−1) salinity, were maintained for nearly 8 weeks before harvest. The genotype biomass in control conditions correlated with the biomass at the two salinity levels. Subsequently, two subsets of 10 genotypes each were selected on the basis of extreme differences in biomass at the two salinity levels while showing relatively similar biomass in control conditions. Carbon isotope discrimination (Δ13C), nitrogen isotope composition (δ15N), and the concentration of nitrogen, phosphorus and several ions (K+, Na+, Ca2+, Mg2+) were analysed in the two subsets for the three treatments. At 12 dS m−1, K+ concentration, K+/Na+ ratio, Δ13C and δ15N correlated positively and Na+ correlated negatively with shoot biomass. Under control conditions and at 17 dS m−1 no correlation was observed. However, the trait that correlated best with genotypic differences in biomass was δ15N at 12 dS m−1. This trait was the first variable chosen at each of the two salinity levels in a stepwise analysis. We consider the possible mechanisms relating δ15N to biomass and the use of this isotopic signature as a selection trait.
Frost tolerance and ice formation in Pinus radiata needles: ice management by the endodermis and transfusion tissues
Authors: Roden John S. , Canny Martin J. , Huang Chen X. , Ball Marilyn C.
Published: February 2009

Conifers are among the most frost tolerant tree species. Cryo-scanning electron microscopy (cryo-SEM) was used to visualise ice formation in pine needles to better understand how conifer leaves manage extracellular ice. Acclimated and unacclimated needles of Pinus radiata (D.Don) were subjected to freezing treatments (at a rate of 2°C h−1), tested for electrolyte leakage and sampled for cryo-SEM analysis. Half maximal electrolyte leakage occurred at –4 and −12°C for unacclimated and acclimated needles, respectively. Ice nucleation occurred at similar temperatures (−3°C) in both acclimated and unacclimated pine needles, indicating that frost tolerance did not increase supercooling. During freezing and thawing, the tissues outside and inside the endodermis shrank and swelled independently, with little or no transfer of water between the two regions. During freezing, mesophyll cells shrank, exhibiting cytorrhysis, and extracellular ice accumulated in gas spaces of the mesophyll tissue. Mesophyll cells from acclimated needles recovered their structure after thawing, and unacclimated mesophyll showed significant damage. In the vascular cylinder, ice accumulated in transfusion tracheids which expanded to occupy areas made vacant by shrinkage of transfusion parenchyma, Strasburger cells and the endodermis. This behaviour was reversible in acclimated tissue, and may play an important role in the management of ice during freeze/thaw events.
Challenges of expansion of voluntary counselling and testing in India
Authors: Solomon Suniti , Venkatesh Kartik K. , Srikrishnan A. K. , Mayer Kenneth H.
Published: February 2009

Voluntary counselling and testing (VCT) has been recognised as an integral element of any effective HIV public health primary prevention and care program. In India, it is currently estimated that 2.0–3.1 million individuals are living with HIV. As low-cost antiretroviral therapy has increasingly become available in India, VCT could be an important link connecting individuals to treatment and care. Major barriers remain for scaling-up of VCT services, including location of VCT centres, HIV-associated stigma, and lack of perception of HIV risk. Future national expansions of VCT services must engage the Indian private sector, which is likely to remain the largest provider of healthcare for the foreseeable future, through scaling-up personnel in these facilities to provide accurate testing and culturally-relevant counselling.
Effects of sexual arousal on vibrotactile detection thresholds in aged men with and without erectile dysfunction
Authors: Jiao Chuanshu , Knight Peter K. , Weerakoon Patricia , McCann Brett D. , Turman A. Bulent
Published: February 2009

Background: Erectile dysfunction (ED) is a common problem in ageing men. Abnormalities in sexual arousal may contribute to its development, and to the failure of pharmacological therapies. However, there are few objective ways of assessing arousal. Sexual arousal has been shown to affect vibrotactile detection thresholds (VDT) in young, healthy men. The present study assessed the effects of sexual arousal on VDT in middle-aged men with and without ED in order to determine whether differences exist between the groups and if such differences may be useful in the evaluation of ED. Methods: VDT in the right index finger of 15 heterosexual men (mean age 74.3 ± 6.0 years) who had been formally diagnosed with ED (ED group) and 16 men (mean age 68.0 ± 6.6 years) who reported no sexual dysfunction in the past 6 months (erectile function (EF) group) were measured before and after watching erotic and control videos using a forced-choice, staircase method at frequencies of 30, 60 and 100 Hz. A mechanical stimulator was used to produce the vibratory stimulus. Results were analysed using repeated-measures analysis of variance. Results: There was no significant effect of watching the erotic video on VDT in subjects in the ED group. In the EF group, VDT was significantly lower at 60 and 100 Hz after watching the erotic video. There was no change in VDT after watching the control video in either group. Conclusion: In response to sexual arousal, VDT in ageing men with normal erectile function decrease, whereas VDT in ageing men with ED remain unchanged.
Attitudes to chlamydia screening in general practice among Australian university students: a pilot study
Authors: Zakher Bernadette , Kang Melissa
Published: February 2009

Background: Chlamydia screening of sexually active young people in general practice is key to the Australian National Sexually Transmissible Infections Strategy 2005–2008. Overseas research indicates that young people have positive attitudes towards opportunistic screening by a general practitioner (GP). This pilot study aims to investigate the attitudes of Australian university students towards chlamydia screening in primary care. Methods: Students (16–25 years) attending a class in one of three faculties at the University of Sydney participated by completing a questionnaire, which collected information about demographics, sexual history, chlamydia knowledge, attitudes towards and preferences for chlamydia screening. Results: One hundred and eighty-five students (78% female) returned questionnaires (participation rate 92%). Arts students were younger, more likely to be sexually active and to report having little or no knowledge of chlamydia. Males in the study were less likely to have had sex as a group compared to the group of females in the sample. Science students were also less likely to have had sex compared to their counterparts in other faculties. Seventy-six percent of students were comfortable with opportunistic testing for chlamydia by their GP. Reasons for not being comfortable included ‘don’t think I’m at risk’ (65%) and ‘not comfortable discussing sexual matters with my GP’ (38%). Although comfortable with GP-based testing, the likelihood of being tested in the upcoming year for most students was low, as was personal concern about chlamydia infection. Conclusions: Findings suggest that the most at risk group for chlamydia infection is not well educated about their risk of infection. The limited numbers of tests among sexually active individuals in this sample indicate that health practitioners are not screening this high-risk group for chlamydia infection.
Patterns of sexual behaviour of male patients before testing HIV-positive in a Cambodian hospital, Phnom Penh
Authors: Sok Phan , Harwell Joseph I. , Dansereau Lynne , McGarvey Stephen , Lurie Mark , Mayer Kenneth H.
Published: February 2009

Background: Sexual behaviours among HIV-positive male patients in Cambodia have not been fully evaluated. Objectives: The patterns of sexual behaviours and social factors were compared between married and single men. Methods: A retrospective cross-sectional survey of 174 male HIV patients was undertaken during March 1999–June 2000 in Phnom Penh. Results: Many participants (61%) reported that they were unaware that their sexual behaviours may have put them at risk of HIV infection. Sexual behaviours included having sex with a sex worker (90%), multiple sexual partners (41%), and both of these behaviours (37%). Two-thirds (69%) reported using a condom when having sex with a sex worker. Condom use with multiple sexual partners was low (24%). A history of condom use with a sex worker was less likely to be reported among married men than single men (P = 0.008). Always using condoms with a sex worker did not differ between married men and single men. Social factors that influenced visiting a sex worker included invitation by a friend (88%), alcohol consumption (74%), and having extra spending money (72%). Multivariate analysis suggests that alcohol consumption (P = 0.008) and having extra spending money (P = 0.02) were strongly associated with visiting a sex worker. Conclusions: In Cambodia, HIV-infected men frequently reported a history of using sex workers. Having multiple sex partners or using a sex worker and multiple sexual partners were not rare. Interventions should target men in settings where alcohol is consumed and to encourage married men to use condoms.
Sexuality, HIV risk and potential acceptability of involving adolescent girls in microbicide research in Kisumu, Kenya
Authors: Montandon Michele , Sahin-Hodoglugil Nuriye Nalan , Bukusi Elizabeth , Agot Kawango , Boland Brigid , Cohen Craig R.
Published: February 2009

Background: Current microbicide clinical trials primarily enroll adult participants; however, females under the age of 18, because of their high rates of HIV acquisition, represent an important population for future microbicide clinical research. We sought to understand the individual, family and community-level factors that may influence the acceptability of microbicide use and research involving adolescent girls. Methods: We conducted 30 interviews with adolescent girls aged 14–17 and nine focus group discussions with adolescent girls, parents and community leaders in Kisumu, Kenya. Participants discussed adolescent sexuality, HIV prevention methods, perceptions about microbicide use and views about microbicide research involving adolescent girls. Results: Adolescent sexual activity is stigmatised yet acknowledged to be a natural part of the ‘adolescent stage.’ Desperation to stop the spread of HIV among youth and support for female-initiated HIV prevention methods led to enthusiasm about microbicides and future microbicide research. Yet concerns about microbicides were numerous and included: difficulty using it in a timely manner due to the rushed, unplanned nature of adolescent sex; a fear of trying experimental products; concerns about microbicide efficacy; and parental worry that supporting microbicide use in youth would defy societal pressures that denounce adolescent sexual activity. Conclusions: Microbicide acceptability for youth in sub-Saharan Africa may be bolstered by desperation for new methods to stop the spread of HIV, yet hindered by misgivings about experimental HIV prevention methods for youth. Understanding and addressing the microbicide’s perceived benefits and shortcomings, as well as the broader context of adolescent sexuality and HIV prevention, may facilitate future research and promotion of microbicides in this high-risk group.
MicroRNA-155 modulates the interleukin-1 signaling pathway in activated human monocyte-derived dendritic cells
Authors: Ceppi Maurizio , Pereira Patricia M. , Dunand-Sauthier Isabelle , Barras Emmanuèle , Reith Walter , Santos Manuel A. , Pierre Philippe
Published: February 2009

In response to inflammatory stimulation, dendritic cells (DCs) have a remarkable pattern of differentiation (maturation) that exhibits specific mechanisms to control immunity. Here, we show that in response to Lipopolysaccharides (LPS), several microRNAs (miRNAs) are regulated in human monocyte-derived dendritic cells. Among these miRNAs, miR-155 is highly up-regulated during maturation. Using LNA silencing combined to microarray technology, we have identified the Toll-like receptor/interleukin-1 (TLR/IL-1) inflammatory pathway as a general target of miR-155. We further demonstrate that miR-155 directly controls the level of TAB2, an important signal transduction molecule. Our observations suggest, therefore, that in mature human DCs, miR-155 is part of a negative feedback loop, which down-modulates inflammatory cytokine production in response to microbial stimuli.
Measurement Properties of Simple Biomechanical Measures of Walking Effort
Authors: Pierrynowski Michael Raymond
Published: February 2009

A simple measure of overall walking effort would be valuable to patients and clinicians to select suitable treatment interventions and to monitor progress. In this paper, the reproducibility and responsiveness of seven potentially useful clinical measures of walking effort are presented. These walking effort outcomes were derived from a compass gait model and space curve displacement, acceleration and differential geometry theory. The walking effort outcomes were primarily calculated from the motion of a point on or in the rigid body pelvis as a patient walked cyclically. These motion data were collected from eight healthy volunteers who each walked on a treadmill for 4 min, at four different speeds, repeated twice. Four of the seven walking effort outcomes clearly had better measurement properties. The path length ratio, acceleration ratio, Frenet–Serret torsion and Frenet–Serret energy had excellent reproducibility (ICC>0.8) and responded to a small change in walking speed (< 0.03 m/s) compared to two versions of the biomechanical efficiency quotient and the Frenet–Serret curvature. The measurement properties of most outcomes were not consistently improved using a point in versus on the pelvis. This study presents four biomechanical walking effort outcomes that have good theoretical underpinnings, excellent reproducibility and responsiveness, are simple and easy to administer with relatively inexpensive equipment, and can be used in real world environments. However, future work must investigate the minimal clinically important change of these outcome measures before they can be used in clinical practice.
Different Strategies for Cancer Treatment: Mathematical Modelling
Authors: Isaeva O. G. , Osipov V. A.
Published: February 2009

We formulate and analyse a mathematical model describing immune response to avascular tumour under the influence of immunotherapy and chemotherapy and their combinations as well as vaccine treatments. The effect of vaccine therapy is considered as a parametric perturbation of the model. In the case of a weak immune response, neither immunotherapy nor chemotherapy is found to cause tumour regression to a small size, which would be below the clinically detectable threshold. Numerical simulations show that the efficiency of vaccine therapy depends on both the tumour size and the condition of immune system as well as on the response of the organism to vaccination. In particular, we found that vaccine therapy becomes more effective when used without time delay from a prescribed date of vaccination after surgery and is ineffective without preliminary treatment. For a strong immune response, our model predicts the tumour remission under vaccine therapy. Our study of successive chemo/immuno, immuno/chemo and concurrent chemoimmunotherapy shows that the chemo/immuno sequence is more effective while concurrent chemoimmunotherapy is more sparing.
Loss of E-Cadherin–mediated Cell–Cell Contacts Activates a Novel Mechanism for Up-Regulation of the Proto-Oncogene c-Jun
Authors: Knirsh Revital , Ben-Dror Iris , Spangler Barbara , Matthews Gideon D. , Kuphal Silke , Bosserhoff Anja K. , Vardimon Lily
Published: February 2009

Loss of E-cadherin–mediated cell–cell contacts can elicit a signaling pathway that leads to acquisition of an invasive phenotype. Here, we show that at the receiving end of this pathway is the proto-oncogene c-Jun, a member of the activator protein-1 family of transcription factors that play a key role in stimulation of cell proliferation and tumor promotion. Cell separation or abrogation of E-cadherin–mediated cell–cell contacts both cause a dramatic increase in accumulation of the c-Jun protein. Unlike growth factors that enhance the expression of c-Jun by activating the transcription of the c-jun gene, the cell contact-dependent increase in c-Jun accumulation is not accompanied by a corresponding increase in c-Jun mRNA or c-Jun protein stability but rather in the translatability of the c-Jun transcript. Consistently, the increase in c-Jun accumulation is not dependent on activation of the mitogen-activated protein kinase or β-catenin pathways but is mediated by signals triggered by the restructured cytoskeleton. Depolymerization of the cytoskeleton can mimic the effect of cell separation and cause a dramatic increase in c-Jun accumulation, whereas Taxol inhibits the cell contact-dependent increase. This novel mechanism of c-Jun regulation seems to underlie the robust overexpression of c-Jun in tumor cells of patients with colon carcinoma.
Statistical methods of background correction for Illumina BeadArray data
Authors: Xie Yang , Wang Xinlei , Story Michael
Published: February 2009

Motivation: Advances in technology have made different microarray platforms available. Among the many, Illumina BeadArrays are relatively new and have captured significant market share. With BeadArray technology, high data quality is generated from low sample input at reduced cost. However, the analysis methods for Illumina BeadArrays are far behind those for Affymetrix oligonucleotide arrays, and so need to be improved.

Results: In this article, we consider the problem of background correction for BeadArray data. One distinct feature of BeadArrays is that for each array, the noise is controlled by over 1000 bead types conjugated with non-specific oligonucleotide sequences. We extend the robust multi-array analysis (RMA) background correction model to incorporate the information from negative control beads, and consider three commonly used approaches for parameter estimation, namely, non-parametric, maximum likelihood estimation (MLE) and Bayesian estimation. The proposed approaches, as well as the existing background correction methods, are compared through simulation studies and a data example. We find that the maximum likelihood and Bayes methods seem to be the most promising.

Contact:  yang.xie@utsouthwestern.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
TOO MUCH LOVE, a Root Regulator Associated with the Long-Distance Control of Nodulation in Lotus japonicus
Authors: Magori Shimpei , Oka-Kira Erika , Shibata Satoshi , Umehara Yosuke , Kouchi Hiroshi , Hase Yoshihiro , Tanaka Atsushi , Sato Shusei , Tabata Satoshi , Kawaguchi Masayoshi
Published: February 2009

Legume plants tightly control the development and number of symbiotic root nodules. In Lotus japonicus, this regulation requires HAR1 (a CLAVATA1-like receptor kinase) in the shoots, suggesting that a long-distance communication between the shoots and the roots may exist. To better understand its molecular basis, we isolated and characterized a novel hypernodulating mutant of L. japonicus named too much love (tml). Compared with the wild type, tml mutants produced much more nodules which densely covered a wider range of the roots. Reciprocal grafting showed that tml hypernodulation is determined by the root genotype. Moreover, grafting a har1 shoot onto a tml rootstock did not exhibit any obvious additive effects on the nodule number, which was further supported by double mutational analysis. These observations indicate that a shoot factor HAR1 and a root factor TML participate in the same genetic pathway which governs the long-distance signaling of nodule number control. We also showed that the inhibitory effect of TML on nodulation is likely to be local. Therefore, TML may function downstream of HAR1 and the gene product TML might serve as a receptor or mediator of unknown mobile signal molecules that are transported from the shoots to the roots.
Functional Contribution of Chorismate Synthase, Anthranilate Synthase, and Chorismate Mutase to Penetration Resistance in Barley–Powdery Mildew Interactions
Authors: Hu Pingsha , Meng Yan , Wise Roger P.
Published: February 2009

Plant processes resulting from primary or secondary metabolism have been hypothesized to contribute to defense against microbial attack. Barley chorismate synthase (HvCS), anthranilate synthase α subunit 2 (HvASa2), and chorismate mutase 1 (HvCM1) occupy pivotal branch points downstream of the shikimate pathway leading to the synthesis of aromatic amino acids. Here, we provide functional evidence that these genes contribute to penetration resistance to Blumeria graminis f. sp. hordei, the causal agent of powdery mildew disease. Single-cell transient-induced gene silencing of HvCS and HvCM1 in mildew resistance locus a (Mla) compromised cells resulted in increased susceptibility. Correspondingly, overexpression of HvCS, HvASa2, and HvCM1 in lines carrying mildew resistance locus o (Mlo), a negative regulator of penetration resistance, significantly decreased susceptibility. Barley stripe mosaic virus–induced gene silencing of HvCS, HvASa2, and HvCM1 significantly increased B. graminis f. sp. hordei penetration into epidermal cells, followed by formation of haustoria and secondary hyphae. However, sporulation of B. graminis f. sp. hordei was not detected on the silenced host plants up to 3 weeks after inoculation. Taken together, these results establish a previously unrecognized role for the influence of HvCS, HvASa2, and HvCM1 on penetration resistance and on the rate of B. graminis f. sp. hordei development in Mla-mediated, barley–powdery mildew interactions.
Site-Specific Risk Factors for Ray Blight in Tasmanian Pyrethrum Fields
Authors: Pethybridge Sarah J. , Gent David H. , Esker Paul D. , Turechek William W. , Hay Frank S. , Nutter Forrest W.
Published: February 2009

Ray blight of pyrethrum (Tanacetum cinerariifolium), caused by Phoma ligulicola var. inoxydablis, can cause defoliation and reductions of crop growth and pyrethrin yield. Logistic regression was used to model relationships among edaphic factors and interpolated weather variables associated with severe disease outbreaks (i.e., defoliation severity ≥40%). A model for September defoliation severity included a variable for the product of number of days with rain of at least 0.1 mm and a moving average of maximum temperatures in the last 14 days, which correctly classified (accuracy) the disease severity class for 64.8% of data sets. The percentage of data sets where disease severity was correctly classified as at least 40% defoliation severity (sensitivity) or below 40% defoliation severity (specificity) were 55.8 and 71%, respectively. A model for October defoliation severity included the number of days with at least 1 mm of rain in the past 14 days, stem height in September, and the product of the number of days with at least 10 mm of rain in the last 30 days and September defoliation severity. Accuracy, sensitivity, and specificity were 72.6, 73.6, and 71.4%, respectively. Youden's index identified predictive thresholds of 0.25 and 0.57 for the September and October models, respectively. When economic considerations of the costs of false positive and false negative decisions and disease prevalence were integrated into receiver operating characteristic (ROC) curves for the October model, the optimal predictive threshold to minimize average management costs was 0 for values of disease prevalence greater than 0.2 due to the high cost of false negative predictions. ROC curve analysis indicated that management of the disease should be routine when disease prevalence is greater than 0.2. The models developed in this research are the first steps toward identifying and weighting site and weather disease risk variables to develop a decision-support aid for the management of ray blight of pyrethrum.
Susceptibility to Phytophthora ramorum and Inoculum Production Potential of Some Common Eastern Forest Understory Plant Species
Authors: Tooley Paul W. , Browning Marsha
Published: February 2009

Twenty-five plant species (21 genera, 14 families), which comprise a portion of the understory in forests of the Eastern United States, were evaluated for susceptibility to infection by Phytophthora ramorum. The degree to which P. ramorum is able to form sporangia and chlamydospores was also assessed on these hosts. Seedlings were spray-inoculated with a mixture (4,000 sporangia/ml) of four P. ramorum isolates followed by incubation in a dew chamber at 20°C in darkness for 5 days. Percent infection on individual leaves/leaflets was assessed visually. Mean percent leaf area infected ranged from 0.7% for Smilax rotundifolia to 93.8% for Kalmia latifolia. Eight plant species tested developed significantly larger lesion areas than those found on susceptible control Rhododendron ‘Cunningham's White’. Fourteen species in addition to the susceptible control exhibited infection of over 90% of their leaves. Sporangia production by P. ramorum varied considerably among plant species, ranging from 36 per cm2 lesion area on Myrica pennsylvannica to 2,001 per cm2 lesion area on Robinia pseudoacacia. Numbers of chlamydospores produced per 6-mm-diameter leaf disk incubated in a P. ramorum sporangia suspension ranged from 25 on Ilex verticillata to 493 on Rhus typhina. The results indicate that many common understory species in Eastern U.S. forests are susceptible to P. ramorum and capable of providing ample sources of inoculum (sporangia and chlamydospores) for forest epidemics should the pathogen be introduced and should temperature and moisture conditions exist that are conducive to disease development.
Pratylenchus neglectusReduces Yield of Winter Wheat in Dryland Cropping Systems
Authors: Smiley Richard W. , Machado Stephen
Published: February 2009

Wheat (Triticum aestivum) in low-precipitation regions of eastern Oregon and Washington is grown mostly as rainfed biennial winter wheat (10-month growing season) planted into cultivated fallow (14-month crop-free period). There are increasing trends for cultivated fallow to be replaced by chemical fallow and for spring cereals to be planted annually without tillage. Most fields are infested by the root-lesion nematodes Pratylenchus neglectus or P. thornei. A replicated multiyear experiment was conducted to compare cropping systems on soil infested by P. neglectus. Populations became greater with increasing frequency of the host crops mustard, pea, and wheat. Annual winter wheat had the highest P. neglectus populations, the lowest capacity to extract soil water, and a lower grain yield compared with wheat grown biennially or rotated with other crops. Populations of P. neglectus did not differ for cultivated versus chemical fallow. Lowest populations occurred in annual spring barley. Winter wheat yield was inversely correlated with the population of P. neglectus. Measures to monitor and to reduce the population of P. neglectus in Pacific Northwest wheat fields are recommended.