bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vivo Immunomodulatory Effect of Tilia x viridis Extracts on Normal Lymphocyte Proliferation: A Direct and an Indirect Action
Authors: Davicino Roberto , Zettler Gabriela , Brizi Margarita Rodriguez , Marrassini Carla , Ferraro Graciela , Filip Rosana , Anesini Claudia
Published: February 2011

The flowers of Tilia species have been used in Europe for many years to treat colds, bronchitis, fever, inflammations and influenza. It is well known that lymphocytes play a role in acquired immunity related to pathogens and tumor cells attachment. The aim of this study was to determine the effect of an aqueous (AE) and a dichloromethane extract (DM) from Tilia x viridis which is widely used and distributed in Argentina, on normal murine lymphocyte proliferation after being administered to mice. Both extracts presented a stimulatory effect on normal murine lymphocyte proliferation. The effect exerted by DM was principally related to macrophage activation, meanwhile AE exerted an important direct effect on lymphocytes related to the rutin presence. The stimulating effect, exerted on normal lymphocytes was due to a protective effect of apoptosis and also to cell IL2 production. Copyright © 2011 John Wiley & Sons, Ltd.
Evaluating traditional Chinese medicine using modern clinical trial design and statistical methodology: application to a randomized controlled acupuncture trial
Authors: Lao Lixing , Huang Yi , Feng Chiguang , Berman Brian M. , Tan Ming T.
Published: February 2011

Traditional Chinese medicine (TCM), used in China and other Asian counties for thousands of years, is increasingly utilized in Western countries. However, due to inherent differences in how Western medicine and this ancient modality are practiced, employing the so‐called Western medicine‐based gold standard research methods to evaluate TCM is challenging. This paper is a discussion of the obstacles inherent in the design and statistical analysis of clinical trials of TCM. It is based on our experience in designing and conducting a randomized controlled clinical trial of acupuncture for post‐operative dental pain control in which acupuncture was shown to be statistically and significantly better than placebo in lengthening the median survival time to rescue drug. We demonstrate here that PH assumptions in the common Cox model did not hold in that trial and that TCM trials warrant more thoughtful modeling and more sophisticated models of statistical analysis. TCM study design entails all the challenges encountered in trials of drugs, devices, and surgical procedures in the Western medicine. We present possible solutions to some but leave many issues unresolved. Copyright © 2011 John Wiley & Sons, Ltd.
Feline Cryptococcosis
Authors: Trivedi Sameer R , Malik Richard , Meyer Wieland , Sykes Jane E
Published: February 2011

Disease summary Cryptococcosis, principally caused by Cryptococcus neoformans and Cryptococcus gattii, is the most common systemic mycosis of cats worldwide. Cats may be infected following inhalation of spores from the environment, with the nasal cavity suspected as being the initial site of colonization and subsequent infection. Other sites of infection in cats are the skin, lungs, lymph nodes, central nervous system (CNS), eyes and, occasionally, periarticular connective tissue. Cryptococcosis can be diagnosed using serology (antigen testing), cytologic examination of smears, histopathology or culture. Treatment of localized disease is generally successful using azole antifungal drugs; however, cats with CNS involvement or disseminated disease require additional treatment with amphotericin B, with or without flucytosine. The prognosis is variable, depending on host and pathogen factors. Some cats require long-term (>1 year) treatment or indefinite therapy.

Patient group Cats of any breed, gender and age may be affected. Retroviral status does not appear to be a risk factor for developing cryptococcosis and indoor cats are not protected from disease.

Global importance Feline cryptococcosis occurs worldwide, but is most frequently reported in Australia, western Canada and the western United States. Species and molecular type vary in different geographical regions and may affect clinical presentation and antifungal susceptibility patterns.

Clinical challenges Serologic tests that detect cryptococcal antigen in serum are sensitive and specific, but false negatives can occur in cats with localized disease. Long-term drug therapy can be expensive and has the potential for toxicity. The extent to which the pathogenicity and antifungal susceptibility is affected by molecular type is currently under study.

Evidence base This review draws on recent literature relating to epidemiology, CNS involvement and advanced diagnostic imaging to update clinicians regarding research findings relevant to clinical practice.
Congenital Portosystemic Shunts in Cats
Authors: Tivers Michael , Lipscomb Victoria
Published: February 2011

Practical relevance Although a relatively uncommon condition, the investigation, diagnosis and initial medical management of feline congenital portosystemic shunts is often undertaken within general practice. Early recognition and appropriate treatment are important to ensure a good outcome.

Clinical challenges Clinical signs associated with CPSSs in cats are extremely variable and can be intermittent. Signs can affect a variety of organ systems including the nervous system, and gastrointestinal and urinary tracts. Thus, the differential diagnosis list may be very long and a CPSS may not be suspected initially. More specific diagnostic tests and diagnostic imaging are indicated but may not be 100% accurate and may not be readily available to the general practitioner.

Audience This review highlights challenging aspects of the investigation and management of CPSSs for the practising veterinarian, but is also relevant to postgraduate students and provides a practical summary for specialists.

Patient group In practice, domestic shorthairs make up the majority of cats with CPSSs. However, Siamese, Persian and Himalayan cats may be more commonly affected than other purebreeds. While cats with CPSSs are typically under 6 months old, the condition is seen in mature animals, which may not have exhibited clinical signs for months or years.

Evidence base Despite several retrospective studies of cats with CPSSs, the evidence base for management of the condition remains limited.
High-glycaemic index and -glycaemic load meals increase the availability of tryptophan in healthy volunteers
Authors: Herrera Christopher P. , Smith Keir , Atkinson Fiona , Ruell Patricia , Chow Chin Moi , O'Connor Helen , Brand-Miller Jennie
Published: February 2011

The purpose of the present study was to determine the influence of the glycaemic index (GI) and glycaemic load (GL) on the ratio of tryptophan (TRP) relative to other large neutral amino acids (LNAA). Ten healthy men (age 22·9 (sd3·4) years; BMI 23·5 (sd1·6) kg/m2) underwent standard GI testing, and later consumed each of a mixed-macronutrient (1915 kJ; 66·5 % carbohydrate (CHO), 17 % protein and 16·5 % fat) high-GI (MHGI), an isoenergetic, mixed-macronutrient low-GI (MLGI) and a CHO-only (3212 kJ; 90 % CHO, 8 % protein, 2 % fat) high-GI (CHGI) meal on separate days. The GI, GL and insulin index values (e.g. area under the curve) were largest after the CHGI meal (117, 200, 158), followed by the MHGI (79, 59, 82) and MLGI (51, 38, 56) meals, respectively (all values were significantly different,P < 0·05). After the MHGI and MLGI meals but not after the CHGI meal, TRP was elevated at 120 and 180 min (P < 0·05). After the CHGI, LNAA was lower compared with the MLGI (P < 0·05); also the rate of decline in LNAA was higher after CHGI compared with MHGI and MLGI (both comparisonsP < 0·05). The percentage increase from baseline in TRP:LNAA after CHGI (23 %) was only marginally higher than after the MHGI meal (17 %;P = 0·38), but it was threefold and nearly significantly greater than MLGI (8 %;P = 0·05). The present study demonstrates that the postprandial rise in TRP:LNAA was increased by additional CHO ingestion and higher GI. Therefore, the meal GL appears to be an important factor influencing the postprandial TRP:LNAA concentration.
The evolution of host specificity in dove body lice
Authors: JOHNSON KEVIN P. , WECKSTEIN JASON D. , BUSH SARAH E. , CLAYTON DALE H.
Published: February 2011

Objective:Conventional wisdom suggests that parasites evolve increased host specialization over time. Host specificity, which describes the number of host species parasitized, is one aspect of host specialization. Recent studies of vertebrate parasites indicate that highly host-specific parasite lineages are not, in fact, evolutionary dead ends; host generalists can evolve from host specialists.

Methods:Using phylogenetic reconstruction methods, we evaluate these patterns in the body lice (Insecta: Phthiraptera) of pigeons and doves, which are permanent ectoparasites that complete their entire life cycle on the body of the host.

Results:We find that species of body lice that parasitize more than one species of host (generalists) are invariably derived from lice parasitizing only one species of host (specialists). A previous study of the wing lice of pigeons and doves also found that generalists were derived from specialists, and that these changes were correlated with the presence of a potentially competing species of wing louse on the same host. For body lice we did not find such a correlation with competition. Instead, the evolution of host generalists in body lice was correlated with host ecology. When we compared body lice that parasitize terrestrial versus arboreal hosts, we found that the evolution of host generalists was associated with terrestrial hosts. In contrast, wing lice showed no correlation between the evolution of generalists and host ecology.

Conclusion:The correlation in body lice suggests that dispersal between host species may occur via the ground. This, in turn, suggests that body lice may fall to the ground more often than wing lice. To test this hypothesis, we conducted an experiment to compare the rate at which body and wing lice are dislodged from the bodies of preening pigeons. Interestingly, our results showed that body lice are dislodged four times more often than wing lice. Therefore, species of terrestrial doves are far more likely to encounter body lice than wing lice on the ground.
Antiparasitic drugs for paediatrics: systematic review, formulations, pharmacokinetics, safety, efficacy and implications for control
Authors: KEISER JENNIFER , INGRAM KATRIN , UTZINGER JÜRG
Published: February 2011

Drug development for paediatric applications entails a number of challenges, such as the wide age spectrum covered – from birth to adolescence – and developmental changes in physiology during biological maturation that influence the efficacy and toxicity of drugs. Safe and efficacious antiparasitic drugs for children are of pivotal importance given the large proportion of burden attributable to parasitic diseases in this age group, and growing efforts to administer, as widely as possible, antiparasitic drugs to at-risk populations, such as infants and school-aged children, often without prior diagnosis. The purpose of this review is to investigate whether antiparasitic drugs have been adequately studied for use in paediatrics. We approached this issue through a systematic review using PubMed and the Cochrane Central Register of Trials covering a period of 10 years and 8 months until the end of August 2010 to identify trials that investigated efficacy, safety and pharmacokinetic (PK) parameters of antiparasitic drugs for paediatrics. Overall, 269 clinical drug trials and 17 PK studies met our inclusion criteria. Antimalarial drugs were the most commonly studied medicines (82·6%). Most trials were carried out in Africa and children aged 2–11 years were the age group most often investigated. Additionally, we critically examined available drug formulations for anthelminthics and identified a number of shortcomings that are discussed. Finally, we shed new light on current proposals to expand ‘preventive chemotherapy’ to preschool-aged children and emphasise that new research, including risk-benefit analyses, are needed before such a strategy can be adopted more widely.
General relativistic plasmas around rotating black holes
Authors: Koide Shinji
Published: February 2011

We show one of possible directions of general relativistic MHD (GRMHD) calculations of astrophysical relativistic jet formation. This was motivated by observations of radio knot ejections associated with high energy flares of an AGN in M87 and micro-quasars. We introduce a modified version of a solar flare model for the phenomenon. In the model, we have to consider a process beyond the ideal GRMHD. Especially, we focus on the special features of general relativistic plasmas around rotating black holes.
Variability studies in blazar jets with SF analysis: caveats and problems
Authors: Emmanoulopoulos Dimitrios , McHardy Ian M. , Uttley Phil
Published: February 2011

Blazars are radio-loud active galactic nuclei (AGN) dominated by relativistic jets seen at small angles to the line-of-sight. They exhibit dramatic flux variations across the electromagnetic spectrum. The fastest variations are observed in the X-ray and γ-ray bands on time-scales of hours or even minutes. Currently, a substantial part of the blazar literature has been based on the study of these temporal variations through the use of structure function (SF) analysis, the results of which are believed to put great constrains on the jet-physics.

The SF is often invoked in the framework of shot-noise models to determine the temporal properties of individual shots within the jet as well as their geometrical sizes. We argue, that for blazar variability studies, the SF-results are sometimes erroneously interpreted leading to misconceptions about the actual source properties. Based on extensive simulations we caution that spurious breaks will appear in the SFs of almost all light-curves, even though these light-curves may contain no intrinsic characteristic time-scale.

Finally, it is also commonly thought that SFs are immune to the sampling problems, such as data-gaps, which affects the estimators of the underlying power spectra density function such as the periodogram. However, we show that SFs are also troubled by gaps which can induce artefacts.
The jet in M87 from e-EVN observations
Authors: Giovannini G. , Casadio C. , Giroletti M. , Beilicke M. , Cesarini A. , Krawczynski H.
Published: February 2011

One of the most intriguing open questions of today's astrophysics is the jet physical properties and the location and the mechanisms for the production of MeV, GeV, and TeV gamma-rays in AGN jets. M87 is a privileged laboratory for a detailed study of the properties of jets, owing to its proximity, its massive black hole, and its conspicuous emission at radio wavelengths and above. We started on November 2009 a monitoring program with the e-EVN at 5 GHz. We present here results of these multi-epoch observations and discuss the two episodes of activity at energy E>100 GeV that occured in this period. One of these observations was obtained at the same day of the first high energy flare. We added to our results literature data obtained with the VLBI and VLA. A clear change in the proper motion velocity of HST-1 is present at the epoch ~2005.5. In the time range 1998 – 2005.5 the apparent velocity is subluminal, and superluminal (~2.7c) after 2005.5.
Intermittent activity of radio sources. Accretion instabilities and jet precession.
Authors: Kunert-Bajraszewska M. , Janiuk A. , Siemiginowska A. , Gawroński M.
Published: February 2011

We consider the radiation pressure instability operating on short timescales (103 - 106 years) in the accretion disk around a supermassive black hole as the origin of the intermittent activity of radio sources. We test whether this instability can be responsible for short ages (<104 years) of Compact Steep Spectrum sources measured by hot spots propagation velocities in VLBI observations and statistical overabundance of Gigahertz Peaked Spectrum sources. The implied timescales are consistent with the observed ages of the sources. We aslo discuss possible implications of the intermittent activity on the complex morphology of radio sources, such as the quasar 1045+352, dominated by a knotty jet showing several bends. It is possible that we are whitnessing an ongoing jet precession in this source due to internal instabilities within the jet flow.
Suzaku observations of the radio galaxy Fornax A west lobe
Authors: Seta Hiromi , Tashiro Makoto S. , Isobe Naoki
Published: February 2011

We performed mapping observations of the Fornax A west lobe with Suzaku in order to measure X-ray brightness distribution. Thanks to the low and stable background of Suzaku, we succeeded in detecting the faint diffuse X-ray emission from the west lobe. Performing careful corrections to the obtained images, we finally measured the X-ray brightness profile extending over the lobe. By comparing the X-ray and radio profiles, the magnetic field found to be fairly constant at ~1 μG over the lobe, while the electron energy distribution is suggested to concentrate on the lobe center.
Radio Loud AGN in the 2XMMi catalogue
Authors: Labiano Alvaro , Guainazzi Matteo , Bianchi Stefano
Published: February 2011

We are carrying out a search for all radio loud Active Galactic Nuclei observed with XMM-Newton, including targeted and field sources to perform a multi-wavelength study of these objects. We have cross-correlated the Verón-Cetty & Verón (2010) catalogue with the XMM-Newton Serendipitous Source Catalogue (2XMMi) and found around 4000 sources. A literature search provided radio, optical, and X-ray data for 403 sources. This poster summarizes the first results of our study.
X-ray radiation of the jets and the supercritical accretion disk in SS 433
Authors: Fabrika Sergei , Medvedev Alexei
Published: February 2011

The observed X-ray luminosity of SS 433 is ~1036 erg/s, it is known that all the radiation is formed in the famous SS 433 jets. The bolometric luminosity of SS 433 is ~1040 erg/s, and originally the luminosity must be realized in X-rays. The original radiation is probably thermalized in the supercritical accretion disk wind, however the missing more than four orders of magnitude is surprising. We have analysed the XMM-Newton spectra of SS 433 using a model of adiabatically and radiatively cooling X-ray jets. The multi-temperature thermal jet model reproduces very well the strongest observed emission lines, but it can not reproduce the continuum radiation and some spectral features. We have found a notable contribution of ionized reflection to the spectrum in the energy range from ~3 to 12 keV. The reflected spectrum is an evidence of the supercritical disk funnel, where the illuminating radiation comes from deeper funnel regions, to be further reflected in the outer visible funnel walls (r ≥ 2 ⋅ 1011 cm). The illuminating spectrum is similar to that observed in ULXs, its luminosity has to be no less than ~1039 erg/s. A soft excess has been detected, that does not depend on the thermal jet model details. It may be represented as a BB with a temperature of Tbb ≈ 0.1 keV and luminosity of Lbb~3 ⋅ 1037 erg/s. The soft spectral component has about the same parameters as those found in ULXs.
The disk/jet connection in the enigmatic microquasar Cygnus X-3
Authors: Koljonen Karri I. I. , Hannikainen Diana C. , McCollough Michael L. , Pooley Guy G. , Trushkin Sergei A. , Tavani Marco , Droulans Robert
Published: February 2011

Simultaneous multi-wavelength observations are crucial for understanding the physics of microquasars, especially the accretion disk/jet connection. The enigmatic microquasar Cygnus X-3 exhibits strong, relativistic jet ejection events producing radio flares up to 20 Jy. These events are preceded by a very soft X-ray state with quenched emission in the radio and hard X-ray bands. Recently, GeV flux was observed by the AGILE and Fermi γ-ray observatories during the newly-identified hypersoft state. By using an extensive database of simultaneous multi-wavelength observations gathered from Cygnus X-3 we can form a more unified picture of the nature of the source and show how the recent γ-ray observations fit into it.
Is there a mildly relativistic jet in SN2007gr?
Authors: Paragi Z. , van der Horst A. J. , Tanaka M. , Taylor G. B. , Kouveliotou C. , Granot J. , Ramirez-Ruiz E. , Pidopryhora Y. , Bourke S. , Campbell R. M. , Garrett M. A. , van Langevelde H. J.
Published: February 2011

SN2007gr was an ordinary type Ic supernova, with a hint of asymmetric explosion seen in the optical polarization spectrum. This type of SNe is occasionally associated with long duration gamma-ray bursts which generate ultra-relativistic jets; no relativistic outflows have yet been found by direct imaging in SNe Ib/c explosions. High resolution very long baseline interferometry (VLBI) data and simultaneous total radio flux density measurements indicated that SN2007gr has expanded mildly relativistically. We performed late time Westerbork Synthesis Radio Telescope (WSRT) observations to measure the level of the underlying extended emission. Comparison of the VLBI and the background-subtracted WSRT and independent VLA data indicate an at least partially resolved source with an average expansion velocity of ≥0.4c, although the VLBI data could be consistent with a fainter source with an expansion velocity of ~0.2c as well.
Afterglow light curves from magnetized GRB flows
Authors: Mimica Petar , Giannios Dimitrios , Aloy Miguel Ángel
Published: February 2011

Using the RMHD code MRGENESIS and the radiative transfer code SPEV we compute multiwavelength afterglow light curves of magnetized ejecta of gamma-ray bursts interacting with a uniform circumburst medium. We are interested in the emission from the reverse shock when ejecta magnetization varies from σ0 = 0 to σ0 = 1. For typical parameters of the ejecta, the emission from the reverse shock peaks for magnetization σ0 ~ 0.01 − 0.1, and is suppressed for higher σ0. We fit the early afterglow light curves of GRB 990123 and 090102 and discuss the possible magnetization of the outflows of these bursts. Finally we discuss the amount energy left in the magnetic field which is available for dissipation at later afterglow stages.
Cosmology and the subclasses of the gamma-ray bursts
Authors: Mészáros Attila , Horváth István , Řípa Jakub , Bagoly Zsolt , Balázs Lajos G. , Veres Péter
Published: February 2011

Several statistical studies - done also by the authors of this contribution - show that there are three subclasses of gamma-ray bursts. They can be called as short, intermediate and long ones, because they can be separated with respect to their durations. The short and intermediate bursts are distributed anisotropically on the sky. This behavior is highly remarkable, and can have a cardinal impact on the cosmology. The subject of this contribution is a survey of this topic.
VLT/NACO detection of a proplyd/jet candidate in the core of Trumpler 14
Authors: Vicente Sílvia , Alves João , Matsuyama Isamu , Bouy Hervé , Spezzi Loredana , Ascenso Joana , Santos Filipe D. , Prusti Timo
Published: February 2011

This paper reports the discovery and presents the results of a first analysis of the observed morphology of a candidate external irradiated circumstellar disk/jet system found in the deep core of Trumpler 14, a cluster an order of magnitude more massive than the only cluster where bona-fide proplyds have been found, the Trapezium cluster in the Orion Nebula.
High-Q microcavities in low-index one-dimensional photonic crystal slabs based on modal gap confinement
Authors: Meng Zi-Ming , Qin Fei , Liu Ye , Li Zhi-Yuan
Published: February 2011

Recently, various high quality factor photonic crystal microcavities have been demonstrated theoretically and experimentally with only one-dimensional periodicity. However, in most cases high-index materials such as silicon were chosen for easily achievable large photonic bandgap and elaborate refractive index modulation or taper structure is required for reducing radiation loss. Here, we present a design of high-Q microcavities in one-dimensional multilayer polystyrene photonic crystal slab structures with a low-index contrast of 1.59:1. Microcavities are introduced by simply decreasing the thickness of layers at the center region to form a double-heterostructure. A resonant mode with a quality factor up to 20 000 is obtained and found to originate from the modal gap confinement by comparing with a Fabry–Perot cavity. The dependence of the maximal quality factor on the cavity length further reveals that the small group velocity of light within the heterostructure cavity contributes significantly to the high-Q. In terms of the high quality factor, ease of fabrication, and large Kerr nonlinearity of polystyrene, our double-heterostructure microcavities will find potential application in realizing all-optical modulation devices.
New equipment and new technique for measuring activity coefficients and Henry's constants at infinite dilution
Authors: Richon Dominique
Published: February 2011

New equipment is presented along with various experimental procedures and setups to cover a large range of applications. It represents a considerable improvement in terms of speed, accuracy, and simplicity with respect to classical gas stripping methods known as “dilutor techniques.” Furthermore, range of conditions of its use is larger in terms of: temperatures (from 90 to 600 K), corrosive power, and toxicity of handled compounds. Solutes that could adsorb inside sampling valves or on the walls of transfer lines between sampling valve and GC detector are now studied easily; thanks to new design and procedure. Activity coefficients of one solute into one solvent at five temperatures, several repeatability tests included, are obtained in worst cases in less than 3 h. One accurate activity coefficient measurement (toluene in water) at one temperature can be realized in less than 2 min, after loading of the dilutor cell, instead of more than half an hour for unreliable results with previous equipment. It must be pointed out that the slope determination (slope of the logarithm of the exponential decay of solute composition in vapor phase which is in equilibrium with liquid phase) is the highest source of errors (flow rate, temperature, number of moles of solute are known with high accuracy with respect to slopes); they are now determined within few ‰ instead of up to tens of % in the most difficult cases leading to higher accuracies of measured activity coefficients, Henry's constants at infinite dilutions or solubility data. Successful comparisons with literature data and reproducibility tests are presented herein.
Spectroscopic measurements of the surface stoichiometry of chemical vapor deposited GaN
Authors: Craft H. S. , Rice A. L. , Collazo R. , Sitar Z. , Maria J.-P.
Published: February 2011

We report on the surface stoichiometry of Ga-polar GaN films grown by metalorganic chemical vapor deposition as studied by x-ray photoelectron spectroscopy. GaN film surfaces are found to be Ga-rich, with Ga:N ratios ranging from 1.3:1 to 3.2:1. In vacuo ion-beam sputter/annealing studies show that these treatments drive the apparent Ga:N surface composition farther from unity, either through a decrease in surface contamination, oxidation of the surface, or both. Simple annealing experiments decrease the Ga:N ratio. The measured GaN ratio is correlated with the GaN growth time, suggesting that residual Ga precursor after growth interacts with the GaN surface as it cools.
Retreat behavior of a charged droplet for electrohydrodynamic inkjet printing
Authors: Yudistira Hadi Teguh , Nguyen Vu Dat , Tran Si Bui Quang , Kang Tae Sam , Park Jung Keun , Byun Doyoung
Published: February 2011

The charged droplet retreat phenomenon in electrohydrodynamic inkjet printing is experimentally observed and theoretically explained. If the charge concentration of a droplet generated from a nozzle is high enough, Coulomb fission is generated a second time and the main droplet retreats to the meniscus on the nozzle. The retreat phenomenon is due to interactions between the charged droplet, the meniscus, and charges on the substrate. The Rayleigh limit is used to give a theoretical estimate of the amount of charge on the droplet and the meniscus during the retreat.
Feedback control of noise in spin valves by the spin-transfer torque
Authors: Bandopadhyay Swarnali , Brataas Arne , Bauer Gerrit E. W.
Published: February 2011

The miniaturization of magnetic read heads and random access memory elements makes them vulnerable to thermal fluctuations. We demonstrate how current-induced spin-transfer torques can be used to suppress the effects of thermal fluctuations. This enhances the fidelity of perpendicular magnetic spin valves. The simplest realization is a dc to stabilize the free magnetic layers. The power can be significantly reduced without losing fidelity by simple control schemes, in which the stabilizing current-induced spin-transfer torque is controlled by the instantaneous resistance.
Influence of surface energy on the stiffness of nanosprings
Authors: Wang Dong-Hui , Wang Gang-Feng
Published: February 2011

When the cross-sectional size of structural elements reduces to nanometers, surface effects become quite important in their mechanical behaviors. In this letter, a theoretical model is proposed to account for surface effects through both surface energy and core-shell model. Through the principle of minimum potential energy, a refined analytical solution is derived for the stiffness of nanosprings. It is shown that surface energy evidently affects the stiffness of nanosprings. The present model provides an efficient tool to analyze the mechanical performance of various nanosized helixes and is also helpful to design nanospring-based devices.
UV-blue photoluminescence from close-packed SiC nanocrystal film
Authors: Fan J. Y. , Li H. X. , Wang Q. J. , Dai D. J. , Chu P. K.
Published: February 2011

We observed stable photoluminescence from close-packed cubic SiC nanocrystals that are self-assembled into thin solid film. The peak wavelength shifts from blue to near UV with increasing excitation energy and follows well the quantum-confinement effect. The photoluminescence excitation spectrum indicates a 3.47 eV bandgap corresponding to a particle size of 2.3 nm. The nanocrystal film shows triple-exponential photoluminescence decay with lifetimes of 2.3, 8.5, and 36.9 ns. The results open the possibility of the solid state UV-blue light emitting by use of the SiC nanocrystals in photonics and photonics/electronics integration.
Huge binding energy of localized biexcitons in Al-rich AlxGa1−xN ternary alloys
Authors: Kittaka Ryo , Muto Hirotaka , Murotani Hideaki , Yamada Yoichi , Miyake Hideto , Hiramatsu Kazumasa
Published: February 2011

Excitonic optical properties of Al-rich AlxGa1−xN ternary alloy epitaxial layers have been studied by means of photoluminescence excitation spectroscopy. On the basis of the energy separation between exciton resonance and two-photon biexciton resonance, the binding energy of biexcitons was estimated to be 56±5 and 48±5 meV for the sample with x=0.81 and 0.89, respectively. The biexciton binding energy of 56 meV was approximately three times as large as the biexciton binding energy of 19 meV in AlN. The large enhancement of the biexciton binding energy resulted from the strong localization of biexcitons due to alloy disorder.
Pulsed laser induced switching of birefringence in nematic phase of photochromic molecules
Authors: Mysliwiec J. , Czajkowski M. , Bartkiewicz S. , Zygadlo K. , Galewski Z. , Sahraoui B.
Published: February 2011

Fast and dynamic switching of liquid-crystalline photochromic system birefringence induced by pulsed laser has been observed. The system consisted of photochromic molecules of 4-heptyl-4′-methoxyazobenzene showing liquid-crystalline nematic state close to the room temperature. Experiment of dynamic birefringence switching was done in optical Kerr effect (OKE) set-up, where for the sample excitation picosecond pulsed laser was used. Simultaneously, HeNe laser was served as a probe beam source. Measurements were done for different voltages applied to the sample. Rise time constant was in the range of microseconds. Full reversibility of the OKE signal was observed.
Ultrasharp ministop-band edge for subnanometer tuning resolution
Authors: Shahid N. , Speijcken N. , Naureen S. , Li M. Y. , Swillo M. , Anand S.
Published: February 2011

We propose and demonstrate a method that enables spectral tuning with subnanometer accuracy, and is based on the transmission ministop-band (MSB) in line-defect multimode photonic crystal (PhC) waveguides. The fabricated MSB filter has ultrasharp edges which show a 30 dB drop in transmission in a 4 nm wavelength span. The use of the ultrasharp MSB edge to (optically) determine PhC fabrication accuracy is demonstrated. The wavelength position of the MSB could be tuned by temperature, with a coefficient of 0.1 nm/°C. The spectral characteristics of the MSB realized in this work are promising for sensing, tuning, and modulation applications.
Distinct neural signatures of threat learning in adolescents and adults
Authors: Lau Jennifer Y. , Britton Jennifer C. , Nelson Eric E. , Angold Adrian , Ernst Monique , Goldwin Michelle , Grillon Christian , Leibenluft Ellen , Lissek Shmuel , Norcross Maxine , Shiffrin Nina , Pine Daniel S.
Published: February 2011

Most teenage fears subside with age, a change that may reflect brain maturation in the service of refined fear learning. Whereas adults clearly demarcate safe situations from real dangers, attenuating fear to the former but not the latter, adolescents’ immaturity in prefrontal cortex function may limit their ability to form clear-cut threat categories, allowing pervasive fears to manifest. Here we developed a discrimination learning paradigm that assesses the ability to categorize threat from safety cues to test these hypotheses on age differences in neurodevelopment. In experiment 1, we first demonstrated the capacity of this paradigm to generate threat/safety discrimination learning in both adolescents and adults. Next, in experiment 2, we used this paradigm to compare the behavioral and neural correlates of threat/safety discrimination learning in adolescents and adults using functional MRI. This second experiment yielded three sets of findings. First, when labeling threats online, adolescents reported less discrimination between threat and safety cues than adults. Second, adolescents were more likely than adults to engage early-maturing subcortical structures during threat/safety discrimination learning. Third, adults’ but not adolescents’ engagement of late-maturing prefrontal cortex regions correlated positively with fear ratings during threat/safety discrimination learning. These data are consistent with the role of dorsolateral regions during category learning, particularly when differences between stimuli are subtle [Miller EK, Cohen JD (2001)Annu Rev Neurosci24:167–202]. These findings suggest that maturational differences in subcortical and prefrontal regions between adolescent and adult brains may relate to age-related differences in threat/safety discrimination.
The Role of Stigma in Understanding Ethnicity Differences in Authoritarianism
Authors: Henry P. J.
Published: February 2011

Ethnic minorities often have shown higher mean levels of authoritarianism compared to Whites. However, no theoretical mechanism has been directly tested to explain these ethnicity differences. Using the stigma literature as a framework, two studies are presented that test a novel explanation for this difference, rooted in the devaluing that accompanies being a member of a stigmatized group in society. The results show that, in Study 1, ethnic minorities reported higher levels of authoritarianism in ways that could not be explained by traditional explanations of authoritarianism, including lower income, lower education, or lack of cognitive complexity. However, in Study 2, when participants were given the opportunity to affirm their sense of worth, ethnic minorities did not differ in their mean levels of authoritarianism compared to Whites. These findings are discussed in the context of understanding ethnic minority endorsement of authoritarianism in terms of self‐regulatory processes that may be related to their stigmatized condition in society.
Effects of coupled vibrations on the parameters of tangentially polarized stripe-electroded piezoelectric cylinders (L)
Authors: Aronov Boris , Bachand Corey , Brown David A.
Published: February 2011

The effects of coupled vibrations on the piezoelectric properties and electroacoustic transducer performance of radially polarized hollow cylindrical elements as a function of the choice of height-to-diameter ratio have been well documented [J. Acoust. Soc. Am. 120(3), 1374–1380 (2006); J. Acoust. Soc. Am. 122(6), 3419–3427 (2007)]. This letter presents experimental work on the effects of coupled (circumferential, axial, and flexural) vibrations on the resonance frequencies, effective electromechanical coupling coefficient, and acoustical performance of tangentially polarized piezoceramic cylindrical elements. Comparisons are made with analytical predictions of the properties of uniformly circumferentially polarized cylinders.
Effects of aspirin on distortion product fine structure: Interpreted by the two-source model for distortion product otoacoustic emissions generation
Authors: Rao Aparna , Long Glenis R.
Published: February 2011

Distortion product otoacoustic emission (DPOAE) fine structure is due to the interaction of two major components coming from different places in the cochlea. One component is generated from the region of maximal overlap of the traveling waves generated by the two primaries and is attributed to nonlinear distortion (nonlinear component). The other component arises predominantly from the tonotopic region of the distortion product and is attributed to linear coherent reflection (reflection component). Aspirin (salicylate) ototoxicity can cause reversible hearing loss and reduces otoacoustic emission generation in the cochlea. The two components are expected to be affected differentially by cochlear health. Changes in DPOAE fine structure were recorded longitudinally in three subjects before, during, and after aspirin consumption. Full data sets were analyzed for two subjects, but only partial data could be analyzed from the third subject. Resulting changes in the two components of DPOAE fine structure revealed variability among subjects and differential effects on the two components. For low-intensity primaries, both components were reduced with the reflection component being more vulnerable. For high-intensity primaries, the nonlinear component showed little or no change, but the reflection component was always reduced.
Second Thoughts About CT Imaging
Authors: Schenkman Lauren
Published: February 2011

Concern that CT scan radiation is causing cancer has focused public scrutiny on radiologists and medical physicists—and riled up controversy among them. Can they find a solution?
Decision-Making
Authors: Schenkman Lauren
Published: February 2011

In 2005, Massachusetts General Hospital (MGH) created and implemented a program that scores the appropriateness of a CT scan every time a doctor orders one and compares its worth to that of other imaging techniques given the patient's symptoms. As a result, the quarterly growth rate in MGH's use of CT scans has dropped from 3% to 0.25%.
Using DNA to Reveal a Mosquito's History
Authors: Pennisi Elizabeth
Published: February 2011

Evolutionary geneticists are applying next-generation DNA sequencing tools to probe further details of the evolutionary history of the mosquito
Wyeomyia smithii
, which became a poster child for climate change when it was found to have migrated north in response to global warming.
Post-Mubarak Era Seen as Opening for Science
Authors: Lawler Andrew
Published: February 2011

As the country's universities prepare to reopen on 26 February after a youth-powered revolution toppled the government, Egyptian and foreign researchers see an opportunity to elevate science, if decades of neglect and corruption can be overcome.
Role of Endosomes in Simian Virus 40 Entry and Infection
Authors: Engel Sabrina , Heger Thomas , Mancini Roberta , Herzog Fabian , Kartenbeck Jürgen , Hayer Arnold , Helenius Ari
Published: February 2011

After binding to its cell surface receptor ganglioside GM1, simian virus 40 (SV40) is endocytosed by lipid raft-mediated endocytosis and slowly transported to the endoplasmic reticulum, where partial uncoating occurs. We analyzed the intracellular pathway taken by the virus in HeLa and CV-1 cells by using a targeted small interfering RNA (siRNA) silencing screen, electron microscopy, and live-cell imaging as well as by testing a variety of cellular inhibitors and other perturbants. We found that the virus entered early endosomes, late endosomes, and probably endolysosomes before reaching the endoplasmic reticulum and that this pathway was part of the infectious route. The virus was especially sensitive to a variety of perturbations that inhibited endosome acidification and maturation. Contrary to our previous models, which postulated the passage of the virus through caveolin-rich organelles that we called caveosomes, we conclude that SV40 depends on the classical endocytic pathway for infectious entry.
The Gut Mucosal Viral Reservoir in HIV-Infected Patients Is Not the Major Source of Rebound Plasma Viremia following Interruption of Highly Active Antiretroviral Therapy
Authors: Lerner Paula , Guadalupe Moraima , Donovan Richard , Hung Jason , Flamm Jason , Prindiville Thomas , Sankaran-Walters Sumathi , Syvanen Michael , Wong Joseph K. , George Michael D. , Dandekar Satya
Published: February 2011

Interruption of suppressive highly active antiretroviral therapy (HAART) in HIV-infected patients leads to increased HIV replication and viral rebound in peripheral blood. Effects of therapy interruption on gut-associated lymphoid tissue (GALT) have not been well investigated. We evaluated longitudinal changes in viral replication and emergence of viral variants in the context of T cell homeostasis and gene expression in GALT of three HIV-positive patients who initiated HAART during primary HIV infection but opted to interrupt therapy thereafter. Longitudinal viral sequence analysis revealed that a stable proviral reservoir was established in GALT during primary HIV infection that persisted through early HAART and post-therapy interruption. Proviral variants in GALT and peripheral blood mononuclear cells (PBMCs) displayed low levels of genomic diversity at all times. A rapid increase in viral loads with a modest decline of CD4
+
T cells in peripheral blood was observed, while gut mucosal CD4
+
T cell loss was severe following HAART interruption. This was accompanied by increased mucosal gene expression regulating interferon (IFN)-mediated antiviral responses and immune activation, a profile similar to those found in HAART-naive HIV-infected patients. Sequence analysis of rebound virus suggested that GALT was not the major contributor to the postinterruption plasma viremia nor were GALT HIV reservoirs rapidly replaced by HIV rebound variants. Our data suggest an early establishment and persistence of viral reservoirs in GALT with minimal diversity. Early detection of and therapy for HIV infection may be beneficial in controlling viral evolution and limiting establishment of diverse viral reservoirs in the mucosal compartment.
Emergency research in children: options for ethical recruitment
Authors: Brierley Joe , Larcher Vic
Published: February 2011

The paucity of research data to guide current paediatric practice has led to children being termed therapeutic orphans. This difficulty is especially pertinent to research in emergency situations, such as acute resuscitation or critical care, where accepted ethical standards for overall research, have historically created practical difficulties for researchers. The welcome establishment of organisations to support UK paediatric research is helping to ensure safer and more effective medications for children, however as the balance between protection and access at the heart of the paediatric research ethical debate shifts to ever increasing access for researchers to children, it remains crucial to ensure the protection for these vulnerable participants. The fundamental protection for research subjects, namely their full informed consent before any recruitment, is not tenable in true emergency situations and so other approaches are warranted if standards are to be improved by human subjects research in such areas. Proxy, deferred and retrospective consent have all been advocated as solutions to this difficulty and this paper explores the ethical justification for these approaches and their utility in safeguarding children and families in emergency situations when traditional informed consent, as currently defined, cannot be obtained in the necessary time frame to enable research.
THERMODYNAMICAL PROPERTIES OF DARK ENERGY IN LOOP QUANTUM COSMOLOGY
Authors: XIAO KUI , ZHU JIAN-YANG
Published: February 2011

Considering an arbitrary, varying equation of state parameter, the thermodynamical properties of dark energy fluid in the semiclassical loop quantum cosmology scenario, where we consider the inverse volume modification, are studied. The equation of state parameters are corrected when we consider the effective behavior. Assuming that the apparent horizon has Hawking temperature, the modified entropy–area relation is obtained, and we find that this relation is different from the one which is obtained by considering the holonomy correction. Considering that the dark energy is in thermal equilibrium with the Hawking radiation of the apparent horizon, we get the expression for the entropy of the dark energy fluid.
SPACE–TIME STRUCTURE IN THE ULTIMATE THEORY
Authors: NAKANISHI NOBORU
Published: February 2011

After criticizing the various existing attempts at extending the concept of the Minkowski space, the following problem is considered: If there is the ultimate theory at all, how should the space–time in it be formulated? The principle of "quantum priority" is proposed, and under this principle, it is argued that the ultimate theory should have the affine symmetry in the framework of quantum gravity. It is shown that the Poincaré symmetry of particle physics is realized as a result of spontaneous breakdown of the affine symmetry.
NEW APPORTIONMENT METHODS USING SIMPLE GAMES
Authors: SHELLSHEAR EVAN
Published: February 2011

This paper investigates the suitability of new apportionment methods based on the idea of preserving the coalition function of the simple game generated by the populations of the states of some country. The new methods fill a gap in the literature concerning apportionment methods based on winning coalitions. The main results in this paper show that the new apportionment methods do not satisfy desirable properties such as house monotonicity, quota, etc.
PURSUIT AND EVASION DIFFERENTIAL GAMES IN HILBERT SPACE
Authors: IBRAGIMOV GAFURJAN I. , HASIM RISMAN MAT
Published: February 2011

We consider pursuit and evasion differential game problems described by an infinite system of differential equations with countably many Pursuers in Hilbert space. Integral constraints are imposed on the controls of players. In this paper an attempt has been made to solve an evasion problem under the condition that the total resource of the Pursuers is less then that of the Evader and a pursuit problem when the total resource of the Pursuers greater than that of the Evader. The strategy of the Evader is constructed.