bluuebunny/crossref_metadata_2025 huggingface dataset:
Fast and efficient manufacturing method of one‐ and two‐dimensional polyethylene terephthalate transmission diffraction gratings by direct laser interference patterning
Authors: Perez‐Hernandez Heidi , Lasagni Andrés F.
Published: March 2012

One‐ and two‐dimensional diffraction gratings were fabricated on commercial polyethylene terephthalate (PET) film by two beam direct laser interference patterning (DLIP) method using a pulse laser (10 ns) with a wavelength of 266 nm. The relative diffraction efficiency of the structured specimens (at 633 nm) in transmission mode was measured and correlated with the topological characteristics of the structured PET substrates. The obtained diffraction gratings made by DLIP show better or similar diffraction efficiencies when compared with the reported efficiency of gratings made by other methods (up to 42.5% for 1 μm arrays), and can be fabricated on large areas in very short processing times (up to 18 cm2/s). POLYM. ENG. SCI., 52:1903–1908, 2012. © 2012 Society of Plastics Engineers
Rubber modification of unsaturated polyester resin with core–shell rubber particles: Effect of shell composition
Authors: Ahmadi M. , Moghbeli M. R. , Shokrieh M. M.
Published: March 2012

Poly(butyl acrylate)/poly(vinyl acetate‐co‐methyl methacrylate) PBA/P(VAc‐co‐MMA) core–shell rubber particles with various shell compositions, i.e., VAc/MMA weight ratios, were used to toughen unsaturated polyester. The morphology and surface‐free energy of the rubber particles were determined by transmission electron microscopy (TEM) and contact angle measurements, respectively. The effect of shell structure on the dispersion state of rubber particles inside the unsaturated polyester resin was studied by scanning electron microscopy and TEM. Increasing MMA units in the shell changed the particle dispersion state from small agglomerates or globally well‐dispersed particles to large aggregates in the cured‐resin matrix. For the blends that contain 5 wt% rubber, the highest un‐notched impact toughness, stress‐intensity factor (KIC), and fracture energy (GIC) were observed for the blend containing PVAc shell particles. The results showed that by increasing the particle level from 5 to 10 wt%, the highest KIC and GIC values were obtained for the blend containing rubber particles with VAc/MMA (80/20 wt/wt) copolymer shell. The crack‐tip damage zone in the neat and rubber‐modified unsaturated polyester resins was observed by means of transmission optical microscopy. In addition, using PVAc shell particles exhibited a minimum reduction in the volume shrinkage and tensile properties of the rubber‐modified resin. POLYM. ENG. SCI., 52:1928–1937, 2012. © 2012 Society of Plastics Engineers
Distinct work‐related, clinical and psychological factors predict return to work following treatment in four different cancer types
Authors: Cooper Alethea F. , Hankins Matthew , Rixon Lorna , Eaton Emma , Grunfeld Elizabeth A.
Published: March 2012

Objective

Many factors influence return to work (RTW) following cancer treatment. However specific factors affecting RTW across different cancer types are unclear. This study examined the role of clinical, sociodemographic, work and psychological factors in RTW following treatment for breast, gynaecological, head and neck, and urological cancer.

Methods

A 12‐month prospective questionnaire study was conducted with 290 patients. Cox regression analyses were conducted to calculate hazard ratios (HR) for time to RTW.

Results

Between 89–94% of cancer survivors returned to work. Breast cancer survivors took the longest to return (median 30 weeks), and urology cancer survivors returned the soonest (median 5 weeks). Earlier return among breast cancer survivors was predicted by a greater sense of control over their cancer at work (HR 1.2; 95% CI: 1.09–1.37) and by full‐time work (HR 2.1; CI: 1.24–3.4). Predictive of a longer return among gynaecological cancer survivors was a belief that cancer treatment may impair ability to work (HR 0.75; CI: 0.62–0.91). Among urological cancer survivors constipation was predictive of longer RTW (HR 0.99; CI: 0.97–1.00), whereas undertaking flexible working was predictive of returning sooner (HR 1.70; CI: 1.07–2.7). Head and neck cancer survivors who perceived greater negative consequences of their cancer took longer to return (HR 0.27; CI: 0.11–0.68). Those reporting better physical functioning returned sooner (HR1.04; CI: 1.01–1.08).

Conclusion

A different profile of predictive factors emerged for the four cancer types. In addition to optimal symptom management and workplace adaptations, the findings suggest that eliciting and challenging specific cancer and treatment‐related perceptions may facilitate RTW. Copyright © 2012 John Wiley & Sons, Ltd.
Effects of point mutations on protein structure are nonexponentially distributed
Authors: Arodź Tomasz , Płonka Przemysław M.
Published: March 2012

Inspection of structure changes in proteins borne by altering their sequences brings understanding of physics, functioning and evolution of existing proteins, and helps engineer modified ones. On single amino acid substitutions, the most frequent mutation type, shifts in backbone conformation are typically small, raising doubts if and how such minor modifications could drive evolutionary divergence. Here, we report that the distribution of magnitudes of structure change on such substitutions is heavy‐tailed — whereas protein structures are robust to most substitutions, changes much larger than average occur with raised odds compared to what would be expected for exponential distribution with the same mean. This nonexponential behavior allows for reconciling the apparent contradiction between the observed conservation of protein structures and the substantial evolutionary plasticity implied in their diversity. The presence of the heavy tail in the distribution promotes structure divergence, facilitating exploration of new functionality, and conformations within folds, as well as exploration of structure space for new folds. Proteins 2012; © 2012 Wiley Periodicals, Inc.
Sann: Solvent accessibility prediction of proteins by nearest neighbor method
Authors: Joo Keehyoung , Lee Sung Jong , Lee Jooyoung
Published: March 2012

We present a method to predict the solvent accessibility of proteins which is based on a nearest neighbor method applied to the sequence profiles. Using the method, continuous real‐value prediction as well as two‐state and three‐state discrete predictions can be obtained. The method utilizes the z‐score value of the distance measure in the feature vector space to estimate the relative contribution among the k‐nearest neighbors for prediction of the discrete and continuous solvent accessibility. The Solvent accessibility database is constructed from 5717 proteins extracted from PISCES culling server with the cutoff of 25% sequence identities. Using optimal parameters, the prediction accuracies (for discrete predictions) of 78.38% (two‐state prediction with the threshold of 25%), 65.1% (three‐state prediction with the thresholds of 9 and 36%), and the Pearson correlation coefficient (between the predicted and true RSA's for continuous prediction) of 0.676 are achieved An independent benchmark test was performed with the CASP8 targets where we find that the proposed method outperforms existing methods. The prediction accuracies are 80.89% (for two state prediction with the threshold of 25%), 67.58% (three‐state prediction), and the Pearson correlation coefficient of 0.727 (for continuous prediction) with mean absolute error of 0.148. We have also investigated the effect of increasing database sizes on the prediction accuracy, where additional improvement in the accuracy is observed as the database size increases. The SANN web server is available at http://lee.kias.re.kr/∼newton/sann/.Proteins 2012; © 2012 Wiley Periodicals, Inc.
Idealized numerical simulations of quasi‐stationary convective systems over the Northwestern Mediterranean complex terrain
Authors: Bresson E. , Ducrocq V. , Nuissier O. , Ricard D. , de Saint‐Aubin C.
Published: March 2012

Northwestern Mediterranean coastal regions are frequently affected by torrential rainfall associated with quasi‐stationary mesoscale convective systems (MCSs). The present work examines how the characteristics of a conditionally unstable flow impinging on the coastal complex terrain of the Northwestern Mediterranean can affect the location and intensity of quasi‐stationary MCSs. The study is based on idealized simulations, but including the major ingredients of Northwestern Mediterranean heavy precipitation events: a moist conditionally unstable marine flow of about 100 km width facing the true terrain, composed of the Massif Central surrounded by the Alps and the Pyrenees.

We find that MCSs are located upstream of the mountain range with a slow flow, whereas with a rapid flow the heaviest precipitation is over the Massif Central slopes. In a similar way, when the lateral environment is drier the heaviest precipitation is located upstream whereas a humid environment favours precipitation over the slopes. The dominant lifting mechanism is strongly related to the location of the system: (1) direct orographic triggering for systems over mountain slopes and (2) cold‐pool triggering for upstream systems. In addition, the neighbouring mountains interplay through deflection of the flow and induced low‐level convergence favoured by slow or dry lateral environments and through cold‐pool blocking within valleys. Copyright © 2012 Royal Meteorological Society
Formation of Lipid Sheaths around Nanoparticle‐Supported Lipid Bilayers
Authors: Ahmed Selver , Savarala Sushma , Chen Yanjing , Bothun Geoffrey , Wunder Stephanie L.
Published: March 2012

High‐surface‐area nanoparticles often cluster, with unknown effects on their cellular uptake and environmental impact. In the presence of vesicles or cell membranes, lipid adsorption can occur on the nanoparticles, resulting in the formation of supported lipid bilayers (SLBs), which tend to resist cellular uptake. When the amount of lipid available is in excess compared with that required to form a single‐SLB, large aggregates of SLBs enclosed by a close‐fitting lipid bilayer sheath are shown to form. The proposed mechanism for this process is one where small unilamellar vesicles (SUVs) adsorb to aggregates of SLBs just above the gel‐to‐liquid phase transition temperature, Tm, of the lipids (as observed by dynamic light scattering), and then fuse with each other (rather than to the underlying SLBs) upon cooling below Tm. The sacks of SLB nanoparticles that are formed are encapsulated by the contiguous close‐fitting lipid sheath, and precipitate below Tm, due to reduced hydration repulsion and the absence of undulation/protrusion forces for the lipids attached to the solid support. The single‐SLBs can be released above Tm, where these forces are restored by the free lipid vesicles. This mechanism may be useful for encapsulation/release of drugs/DNA, and has implications for the toxic effects of nanoparticles, which may be mitigated by lipid sequestration.
The Importance of Dehydration in Determining Ion Transport in Narrow Pores
Authors: Richards Laura A. , Schäfer Andrea I. , Richards Bryce S. , Corry Ben
Published: March 2012

The transport of hydrated ions through narrow pores is important for a number of processes such as the desalination and filtration of water and the conductance of ions through biological channels. Here, molecular dynamics simulations are used to systematically examine the transport of anionic drinking water contaminants (fluoride, chloride, nitrate, and nitrite) through pores ranging in effective radius from 2.8 to 6.5 Å to elucidate the role of hydration in excluding these species during nanofiltration. Bulk hydration properties (hydrated size and coordination number) are determined for comparison with the situations inside the pores. Free energy profiles for ion transport through the pores show energy barriers depend on pore size, ion type, and membrane surface charge and that the selectivity sequence can change depending on the pore size. Ion coordination numbers along the trajectory showed that partial dehydration of the transported ion is the main contribution to the energy barriers. Ion transport is greatly hindered when the effective pore radius is smaller than the hydrated radius, as the ion has to lose some associated water molecules to enter the pore. Small energy barriers are still observed when pore sizes are larger than the hydrated radius due to re‐orientation of the hydration shell or the loss of more distant water. These results demonstrate the importance of ion dehydration in transport through narrow pores, which increases the current level of mechanistic understanding of membrane‐based desalination and transport in biological channels.
Excessive Sodium Ions Delivered into Cells by Nanodiamonds: Implications for Tumor Therapy
Authors: Zhu Ying , Li Wenxin , Zhang Yu , Li Jing , Liang Le , Zhang Xiangzhi , Chen Nan , Sun Yanhong , Chen Wen , Tai Renzhong , Fan Chunhai , Huang Qing
Published: March 2012

Nanodiamonds (NDs) possess many excellent physical and chemical properties that make them attractive materials for applications in biomedicine. In this paper, the adsorption and delivery of a large amount of sodium ions into the cell interior by NDs in serum‐free medium is demonstrated. The excess sodium ions inside the cells induce osmotic stresses followed by cell swelling and an increase in the intracellular levels of calcium and reactive oxygen species (ROS), which leads to severe cellular damage. In complete culture medium, however, serum proteins wrapped around the NDs effectively prevent the sodium ions from adsorbing onto the NDs, and thus the NDs show no cytotoxicity. This work is the first to elaborate on the correlation between the sodium ions adsorbed on the nanomaterials and their bio‐effects. Excessive ions delivered into cells by NDs might have potential applications in tumor therapy.
Strength reduction factor demands for building structures under different seismic levels
Authors: Thuat Dinh Van
Published: March 2012

Damage levels of building structures under a design earthquake are closely related to the assigned values of strength reduction factors. This paper is to investigate the strength reduction factor demands of building structures that were designed considering various earthquake ground intensity levels, soil ground types, and strength reduction factors. In the investigation, a huge number of rigorous nonlinear inelastic dynamic response analyses of various analytical models of five‐story and nine‐story frame structures were conducted under various generated ground motions with variations in phrase angles but identical response spectral acceleration amplitudes. Various scaled earthquake records were also considered for evidence of the investigation. The obtained results showed that when the same values of the strength reduction factors were used for determination of the design lateral seismic forces, the damage and reliability level demands of the structures designed for moderate seismic areas were much less than those for severe seismic ones. As a result, it is proposed that the strength reduction factor demands given in design codes can additionally be expressed in a linear relation of the maximum ground acceleration. Copyright © 2012 John Wiley & Sons, Ltd.
Monochromatic waves in saturated porous materials with anisotropic permeability
Authors: Wilmanski K.
Published: March 2012

In the paper we investigate the propagation conditions of monochromatic waves in a saturated poroelastic material described by a generalization of Biot's equations. This generalization concerns anisotropic properties of the permeability. Mechanical properties of the system are assumed to be described by isotropic constitutive relations but the permeability is given in terms of a tensor of tortuosity. In particular we analyze the propagation in one of the principal directions of this tensor. For this particular monochromatic wave we show the existence of the purely transversal wave. We prove the existence of two modes of such waves and investigate their behavior as functions of the frequency. A practical application in nondestructive testing of anisotropic materials is indicated.
Bending of a bi‐material cantilever beam, with consideration of the role of the interfacial shearing stress
Authors: Suhir E. , Nicolics J.
Published: March 2012

A simple, easy‐to‐use and physically meaningful analytical (“mathematical”) model for the prediction of the interfacial shearing stress in, and the maximum bow of, a bi‐material cantilever beam is developed. The beam experiences bending under the action of a lateral concentrated force applied to its free end. It is shown that the effect of the longitudinal interfacial compliance of the beam should be considered for short beams with not‐very‐stiff interfaces.
Incidence of cervical intraepithelial neoplasia in a cohort of HIV‐infected women
Authors: Araújo Angela C.L. , Carvalho Nara O. , Teixeira Nara C. , Souza Tatiana T. , Murta Érica D. , Faria Iwens M. , Corrêa Christine M. , Lima Maria I.M. , del Castillo Dora M. , Melo Victor H.
Published: March 2012

Objective

To assess cervical intraepithelial neoplasia (CIN) incidence in HIV‐positive women and the risk factors for these lesions.

Methods

A retrospective and longitudinal cohort study was conducted from June 13, 1997, to December 18, 2009. At the first visit, the 348 participants had a normal cytologic finding but a negative Schiller test result, or an abnormal cytologic finding but no histologic diagnosis of CIN. Infection with HPV was detected by polymerase chain reaction. The main outcome measure was CIN incidence.

Results

During a mean follow‐up of 40 months, 47 women (13.5%) developed CIN, for an incidence of 4.1 cases per 100 person‐years of follow‐up. The HPV prevalence was 68.1%, 42 women (89.4%) developed CIN 1, and no invasive cervical cancers were identified. On multivariate analysis, women younger than 19 years at first sexual intercourse (RR, 2.6; 95% CI, 1.24–5.35) and women who had never used antiretrovirals or used them only during pregnancy (RR, 2.3; 95% CI, 1.31–4.19) were at higher risk for CIN.

Conclusion

The CIN incidence was low despite the high HPV prevalence. Being younger than 19 years at first sexual intercourse and not using antiretroviral medications were found to be the main risk factors for CIN.
The effects of retail channel integration through the use of information technologies on firm performance
Authors: Oh Lih‐Bin , Teo Hock‐Hai , Sambamurthy Vallabh
Published: March 2012

The ability of information technologies (ITs) to integrate activities and offerings across multiple channels offers a promising opportunity for retail firms to enhance their relationship with their customers and firm performance. Consumers value the flexibility to learn about the available offerings, complete their orders and obtain customer service across different channels in a convenient and integrated manner. Therefore, the retail industry has begun to use IT extensively to automate and integrate business processes across their traditional and online channels. This study examines the impacts of the use of IT by retail firms in integrating channel activities for selling to customers. Our research model argues that retail channel integration through IT should enhance the efficiency and innovation of a retail firm. In turn, these improvements should enhance their overall performance. We also propose that the environmental dynamism would moderate the effects of improvements in efficiency and innovation on firm performance. We draw upon recent theories in organizational resource integration and organizational learning to develop our research model and hypotheses. Based on survey data from 125 multichannel retailers in Singapore, we find that retail channel integration through the use of IT allows firms to not only be efficient in delivering the current offerings, but also be innovative in creating future offerings. Further, we find that environmental dynamism does positively moderate the effects of innovation ability on performance. Our results provide managerial insights for firms involved in digital integration not only in the retail sector but also in other service industries. These findings could also serve as a foundation for further research on service operations management for firms with both physical and online operations.
Nazareno Strampelli, the ‘Prophet’ of the green revolution
Authors: SALVI S. , PORFIRI O. , CECCARELLI S.
Published: March 2012

23 January 2012 marked 70 years since the death of the Italian plant breeder Nazareno Strampelli (1866–1942), one of the most important plant geneticists of the 20th century. During the first 30 years of what is known as the ‘short century’, Strampelli was among the first, in Europe and in the world, to systematically apply Mendel's laws to plant breeding, particularly to wheat breeding which resulted in varieties characterized by rust resistance, early flowering and maturity and short straw. Due to Strampelli's varieties Italian wheat production doubled, an achievement that during the fascist regime was referred to as the ‘Wheat Battle’.

Some of Strampelli's wheats, such as Mentana, Ardito and San Pastore, were used as parents in the breeding programmes of several countries after the Second World War; they also had a key role in the first phase of Norman Borlaug's Green Revolution, being instrumental in the development of the high-yielding varieties of the future Nobel Peace Laureate.

A century after the key cross in which Strampelli, 30 years before Borlaug, used the genes for short straw and earliness in wheat breeding, his name and his work are not known and appreciated as they deserve, despite the recent evidence that the resistance to the new rust races could derive from the very same resistance genes identified by the Italian breeder at the beginning of the 20th century.
Secure Property as a Bottom-Up Process: Firms, Stakeholders, and Predators in Weak States
Authors: Markus Stanislav
Published: March 2012

How do property rights become secure? How does rule of law take hold in an economy? The author uses an original survey of 516 firms in Russia and Ukraine, as well as interview-based case studies, to reexamine these fundamental issues of political economy. Most states in the developing world lack the requisite time horizons and institutional capacity to make the credible commitments emphasized in the literature. In this context, the author argues that firms can enforce their property rights without resort to mafias by forming alliances with stakeholders such as foreign actors, community residents, and labor. These stakeholders can impose costs on the potential aggressors through diverse political strategies, allowing firms to defend their property rights not only from private predators but also from the state. The article evaluates this “bottomup” theory of secure property rights against existing state-based theorizing.
The dual orexin receptor antagonist almorexant, alone and in combination with morphine, cocaine and amphetamine, on conditioned place preference and locomotor sensitization in the rat
Authors: Steiner Michel Alexander , Lecourt Hugues , Jenck François
Published: March 2012

Dual orexin receptor (OXR) antagonists emerge as a novel therapeutic class to treat insomnia that, based on anti-addictive effects of selective OXR type 1 antagonists in rats, might be associated with less abuse liability than commonly used γ-aminobutyric acid (GABA) receptor modulators. Here, we studied the effects of the sleep-enabling dual OXR antagonist almorexant on conditioned place preference (CPP) and locomotor sensitization in rats. First, we compared almorexant to the GABA metabolite γ-hydroxybutyrate (GHB), which is clinically used as a sleep-inducing drug and which is associated with mild abuse liability. Whereas conditioning with GHB induced significant place preference, conditioning with almorexant did not. Second, we tested the potential of almorexant to interfere with the conditioned rewarding or locomotor sensitizing effects related to psychostimulants or opiates. Almorexant attenuated the expression of CPP to high doses of cocaine (15 mg/kg) and d.l-amphetamine (2 mg/kg), but not to high dose of morphine (10 mg/kg). Conversely, almorexant interfered with the expression of locomotor sensitization to morphine, but not with that to cocaine and d.l-amphetamine. Third, we observed that chronic almorexant (12 d) treatment in morphine, cocaine or amphetamine pre-conditioned and locomotor-sensitized rats had no influence on the maintenance of CPP and locomotor sensitization when tested after almorexant washout. Our findings suggest that almorexant itself does not exert conditioned rewarding effects in the rat and that it may acutely interfere with the expression of CPP or locomotor sensitization in a drug-dependent manner (monoaminergic psychostimulants vs. opiates).
Control of pore fluid pressure diffusion on fault failure mode: Insights from the 2009 L'Aquila seismic sequence
Authors: Malagnini Luca , Lucente Francesco Pio , De Gori Pasquale , Akinci Aybige , Munafo' Irene
Published: March 2012

The MW 6.13 L'Aquila earthquake ruptured the Paganica fault on 2009/04/06 at 01:32 UTC, and started a strong sequence of aftershocks. For the first four days, the region north of the hypocenter of the main quake was shaken by three large events (MW ∼ 5.0) that ruptured different patches of the Monti della Laga fault (hereafter “Campotosto”). In our hypothesis, these aftershocks were induced by a dramatic reduction in the fault's shear strength due to a pulse of pore fluid pressure released after the L'Aquila main earthquake. Here we model the time evolution of the pore fluid pressure northward from the main hypocenter. We show that, during the sequence, the Campotosto fault failed in multiple episodes, when the specific patches/asperities underwent fluid pressure‐related strength reductions of 7–10 MPa. Although such drops in strength are very large in amplitude, the contribution of other weakening mechanisms (perturbations of the Coulomb shear stress, and/or dynamic stresses induced by passing seismic waves) cannot be ruled out by our observations. However, the Coulomb shear stress variations either had negative amplitudes down to −0.2 MPa (i.e., tended to inhibit further seismic activity), or had very small positive amplitudes (<0.05 MPa). Paleoseismological evidence supports the hypothesis that larger events (MW 6.5–7) have occurred on the Paganica fault [EMERGEO Working Group, 2009], whereas Lucente et al. [2010] concluded that an important migration of pore fluids characterized the preparatory phase of the L'Aquila main shock. Consequently, the MW 6.13 L'Aquila earthquake may be analogous, at a larger scale, to one of the three Campotosto largest aftershocks. The complex behavior observed for the L'Aquila‐Campotosto fault system seems to be common to other seismogenic structures in the Central Apennines (e.g., the Umbria‐Marche fault system), and need to be taken into consideration for the assessment of seismic hazard.
Can we use ice sheet reconstructions to constrain meltwater for deglacial simulations?
Authors: Bethke Ingo , Li Camille , Nisancioglu Kerim H.
Published: March 2012

Freshwater pulses from melting ice sheets are thought to be important for driving deglacial climate variability. This study investigates challenges in simulating and understanding deglacial climate evolution within this framework, with emphasis on uncertainties in the ocean overturning sensitivity to meltwater inputs. The response of an intermediate complexity model to a single Northern Hemisphere meltwater pulse is familiar: a weakening of the ocean overturning circulation in conjunction with an expansion of sea ice cover and a meridional temperature seesaw. Nonlinear processes are vital in shaping this response and are found to have a decisive influence when more complex scenarios with a history of pulses are involved. A meltwater history for the last deglaciation (21–9 ka) was computed from the ICE‐5G ice sheet reconstruction, and the meltwater was routed into the ocean through idealized ice sheet drainages. Forced with this meltwater history, model configurations with altered freshwater sensitivity produce a range of outcomes for the deglaciation, from those in which there is a complete collapse of the overturning circulation to those in which the overturning circulation weakens slightly. The different outcomes are interpreted in terms of the changing hysteresis behavior of the overturning circulation (i.e., non‐stationary freshwater sensitivity) as the background climate warms through the course of the deglaciation. The study illustrates that current uncertainties in model sensitivity are limiting in efforts to forward‐model deglacial climate variability. Furthermore, ice sheet reconstructions are shown to provide poor constraints on meltwater forcing for simulating the deglaciation.
Investigating the Metabolic Changes due to Visual Stimulation using Functional Proton Magnetic Resonance Spectroscopy at 7 T
Authors: Lin Yan , Stephenson Mary C , Xin Lijing , Napolitano Antonio , Morris Peter G
Published: March 2012

Proton magnetic resonance spectroscopy (1H-MRS) has been used to demonstrate metabolic changes in the visual cortex on visual stimulation. Small (2% to 11%) but significant stimulation induced increases in lactate, glutamate, and glutathione were observed along with decreases in aspartate, glutamine, and glycine, using 1H-MRS at 7 T during single and repeated visual stimulation. In addition, decreases in glucose and increases in γ-aminobutyric acid (GABA) were seen but did not reach significance. Changes in glutamate and aspartate are indicative of increased activity of the malate–aspartate shuttle, which taken together with the opposite changes in glucose and lactate, reflect the expected increase in brain energy metabolism. These results are in agreement with those of Mangia et al. In addition, increases in glutamate and GABA coupled with the decrease in glutamine can be interpreted in terms of increased activity of the neurotransmitter cycles. An entirely new observation is the increase of glutathione during prolonged visual stimuli. The similarity of its time course to that of glutamate suggests that it may be a response to the increased release of glutamate or to the increased production of reactive oxygen species. Together, these observations constitute the most detailed analysis to date of functional changes in human brain metabolites.
Direct observation of ferroelectric polarization-modulated band bending at oxide interfaces
Authors: Huang B. C. , Chen Y. T. , Chiu Y. P. , Huang Y. C. , Yang J. C. , Chen Y. C. , Chu Y. H.
Published: March 2012

This study presents a direct visualization of the influences of ferroelectric polarization on the electronic properties of the Schottky contact at the Nb-SrTiO3/BiFeO3 hetero-interface using scanning tunneling microscopy and spectroscopy (STM/S). The evolution of the local density of states across the Nb-SrTiO3/BiFeO3 interface reveals the interfacial band alignment and the characteristic quantities of the metal/ferroelectric contact. The unique combination of STM and STS in this study delivers an approach to obtain critical information on the interfacial electronic configurations of ferroelectric oxide interfaces and also their variation with ferroelectric polarization switching.
Reflectivity of very low energy electrons (< 10 eV) from solid surfaces: Physical and instrumental aspects
Authors: Cazaux Jacques
Published: March 2012

The impact of very low energy electrons (VLEE) on solid surfaces plays an important role in various fields of modern technology. Plasma physics, space research and particle-accelerators and progress in these fields are based partly on investigation of VLEE emission and reflection properties as obtained from laboratory measurements. Here the influence of the material composition and of the angle of incidence on the reflectivity, R, of VLEE is derived by the use of simple quantum mechanical arguments showing a rapid decrease of R from 100% when the incident energy of electrons increases from 0 eV while the surface sensitivity increases. The measurements depend significantly on the potential referencing between the electron source, the sample, and the detector, as well as of the energy spread of the incident electrons. VLEE thin film transmission is briefly considered and various practical consequences of the contrasts (crystalline, topographic, doping) as reported in scanning low energy electron microscopy (SLEEM) are discussed. The present developments may be transposed easily to any kind of solid sample and the possibility of imaging the local vacuum level (or work function) change with a minimum of radiation damage is suggested.
Magnetic superlens-enhanced inductive coupling for wireless power transfer
Authors: Huang Da , Urzhumov Yaroslav , Smith David R. , Hoo Teo Koon , Zhang Jinyun
Published: March 2012

We investigate numerically the use of a negative-permeability “perfect lens” for enhancing wireless power transfer between two current carrying coils. The negative permeability slab serves to focus the flux generated in the source coil to the receiver coil, thereby increasing the mutual inductive coupling between the coils. The numerical model is compared with an analytical theory that treats the coils as point dipoles separated by an infinite planar layer of magnetic material [Urzhumov et al., Phys. Rev. B 19, 8312 (2011)]. In the limit of vanishingly small radius of the coils, and large width of the metamaterial slab, the numerical simulations are in excellent agreement with the analytical model. Both the idealized analytical and realistic numerical models predict similar trends with respect to metamaterial loss and anisotropy. Applying the numerical models, we further analyze the impact of finite coil size and finite width of the slab. We find that, even for these less idealized geometries, the presence of the magnetic slab greatly enhances the coupling between the two coils, including cases where significant loss is present in the slab. We therefore conclude that the integration of a metamaterial slab into a wireless power transfer system holds promise for increasing the overall system performance.
Surface charge density model for predicting the permittivity of liquid mixtures and composites materials
Authors: Iglesias T. P. , Reis João Carlos R.
Published: March 2012

The case “cube inside cube” for the recent predictive equivalent capacitance model (ECM) is resolved into three different analytic equations expressing the relative permittivity of a composite in terms of constituent relative permittivities and inclusion volume fraction, and they are averaged analytically (ECM-average). Although ECM represents an advance, it requires a specific calculation for each inclusion shape. Sharing the same assumptions and basic physics with ECM an alternative numerical model, named surface charge density model (SCDM), is developed. Using this model it is shown that ECM is an approximation in any of the three solutions mentioned above. Since the approach “cube inside cube” leads to isotropic systems where the volume fraction of the inclusion can be varied from zero to one, an attempt is made to apply SCDM and ECM to binary liquid mixtures. Literature values for relative permittivities of some organic–organic liquid systems are used to test values predicted by SCDM and ECM, as well as by four classic predictive mixing equations. It is concluded that ECM-average and SCDM can be applied to binary liquid mixtures with dissimilar molar volumes, when the component of bigger molar volume is considered as inclusion, and that ECM-average is generally an acceptable approximation to the numerical SCDM. Present results suggest that the SCDM performs better when bigger molar volume is associated with higher permittivity. Finally, using an example in 2D for an anisotropic inclusion it is shown that the assumption of non-reflecting boundary potential, which has been used by different authors, is satisfied only for highly symmetric inclusion distributions.
An evaluation of anti-oxidative protection for cells against atmospheric pressure cold plasma treatment
Authors: Ma Ruonan , Feng Hongqing , Li Fangting , Liang Yongdong , Zhang Qian , Zhu Weidong , Zhang Jue , Becker Kurt H. , Fang Jing
Published: March 2012

With the development of plasma medicine, safety issues are emerging as a serious concern. In this study, both intracellular (genetic engineering) and extracellular (scavengers) measures were tested in an effort to determine the best protection for cells against plasma-induced oxidative stress. All results of immediate reactive species detection, short term survival and long term proliferation, suggest that intracellular pathways are superior in reducing oxidative stress and cell death. This work provides a potential mechanism to enhance safety and identifies precautionary measures that should be taken in future clinical applications of plasmas.
Impedance model of trap states for characterization of organic semiconductor devices
Authors: Burtone L. , Ray D. , Leo K. , Riede M.
Published: March 2012

An equivalent circuit to characterize energy distribution of trap states present in organic semiconductors by impedance spectroscopy is proposed. We analyze the impedance spectra of a small-molecule organic solar cell and observe the contribution of trap states at low frequencies. Starting from previously reported equivalent circuits and a theoretical model based on the integration of a general traps distribution, we develop an equivalent circuit, which is able to describe the energetic distribution of trap states typically observed in organic semiconductors. The experimental data can be reproduced by our equivalent circuit, and we estimate a density of trap states in a Zn-phthalocyanine:C60 bulk heterojunction to be about 1.9 ± 0.6 × 1016 cm–3 eV–1.
Conditional vorticity budget of coherent and incoherent flow contributions in fully developed homogeneous isotropic turbulence
Authors: Wilczek Michael , Kadoch Benjamin , Schneider Kai , Friedrich Rudolf , Farge Marie
Published: March 2012

We investigate the conditional vorticity budget of fully developed three-dimensional homogeneous isotropic turbulence with respect to coherent and incoherent flow contributions. The coherent vorticity extraction based on orthogonal wavelets allows to decompose the vorticity field into coherent and incoherent contributions, of which the latter are noise-like. The impact of the vortex structures observed in fully developed turbulence on statistical balance equations is quantified considering the conditional vorticity budget. The connection between the basic structures present in the flow and their statistical implications is thereby assessed. The results are compared to those obtained for large- and small-scale contributions using a Fourier decomposition, which reveals pronounced differences.
Free-space carpet-cloak based on gradient index photonic crystals in metamaterial regime
Authors: Yin Ming , Yong Tian Xiao , Xue Han Hao , Chen Li Di
Published: March 2012

A free-space broadband carpet-cloak, designed based on transformations optics and quasi-conformal mapping, was realized with all-dielectric gradient index rod-connected diamond-structured photonic crystals (PCs) in metamaterial regime. Complex three-dimensional sample with smooth continuous changing unit cells was fabricated precisely by stereolithography (SL) using photo-curable resin. Thus, by gradually varying the unit cell constitutive parameters of the diamond-based PCs with nearly isotropic properties, the required complex spatial distribution of the refractive index profile was ideally achieved to reduce the scattering of the electromagnetic wave. The non-resonant property of the sub-wavelength PCs unit cell resulted in broad bandwidth and relatively low loss.
Oxygen-vacancy and depth-dependent violet double-peak photoluminescence from ultrathin cuboid SnO2 nanocrystals
Authors: Liu L. Z. , Wu X. L. , Xu J. Q. , Li T. H. , Shen J. C. , Chu Paul K.
Published: March 2012

A double peak in the violet region between 360 and 400 nm is observed from the photoluminescence spectra acquired from cuboid SnO2 nanocrystals and the energy separation between the two subpeaks increases with nanocrystal size. The phenomenon arises from band edge recombination caused by different in-depth distributions of oxygen vacancies (OVs). Density functional theory calculations disclose that variations in the oxygen vacancies with depth introduce valence-band peak splitting leading to the observed splitting and shift of the double peak.
X-Ray Spectroscopy and Structure Elucidation of Reactive Electrogenerated Tri-iron Carbonyl Sulfide Clusters
Authors: Yeo Joey , Cheah Mun Hon , Bondin Mark I. , Best Stephen P.
Published: March 2012

The design and operation of electrosynthesis cells for generation of samples for X-ray absorption spectroscopy are described. Optimization of continuous-flow methods allows the generation of highly reducing species, which may be combined with spectroscopic validation of the composition of the electrogenerated solution. It is shown that the large sample volume (10 mL) of the 1–10 mM (in the absorbing element) solution required for such experiments can be reduced to ~100 μL using a strategy in which the in situ electrosynthesis cell is amenable to freeze-quenching and transfer to a beamline cryostat. The working electrode in this case doubles as the X-ray absorption spectroscopy sample cell. The application of these techniques is illustrated by the reduction chemistry of Fe3S2(CO)9, 3Fe2S. Spectra recorded in the near-edge region confirm that quantitative preparation of samples of 3Fe2S, 3Fe2S1– and 3Fe2S2– can be prepared by either approach, but samples of a more reduced form, identified as [Fe3S(CO)9]2–, could only be generated using continuous-flow electrosynthesis techniques. Differences in the structural chemistry of the 3Fe2S0/1–/2– redox series were examined from the perspective of their near-edge spectra and the structures of 3Fe2S1– and 3Fe2S2– forms were deduced by a combination of computational (density functional theory), spectroscopic and X-ray absorption fine-structure analyses. These show that addition of the first electron is predominantly localized in one of the Fe–Fe bonds; cleavage of the Fe–Fe bond by addition of a second electron to the Fe–Fe antibonding orbital is associated with a more substantial rearrangement of the molecule. The reduced compounds have structural similarities to the reduced dithiolate-bridged di-iron hexacarbonyl compounds and this is related to the weak electrocatalytic proton reduction exhibited by Fe3S2(CO)9. The methods described provide a strategy for the collection and analysis of experimental data directed towards structure elucidation of redox-activated solution-state complexes.
Lifestyle Advice for Urinary Stone Disease
Authors: Walsh Alexandra , Hotston Matthew Richard , Keeley Francis Xavier
Published: March 2012

Urinary stone disease is an increasingly prevalent condition for many patients under the care of GPs. Recognizing the importance of lifestyle factors on stone development will enable GPs to manage their ‘at-risk’ patients more effectively. The aim of this article is to describe the important lifestyle factors that when modified will reduce both patients' risk of stone development and recurrence. Furthermore, the significance of stone disease as a marker of more systemic diseases, such as metabolic syndrome, is highlighted.
Vasomotor Rhinitis
Authors: Smith Helen , Glew Simon
Published: March 2012

Rhinitis is characterized by nasal discharge, congestion, blockage and sneezing. These symptoms can have a variety of aetiologies, including allergic, non-allergic or infective causes. This article focuses on the diagnosis and management of patients with non-allergic non-infective rhinitis, but clearly, there are overlaps with the management of rhinitis due to other causes. Non-allergic rhinitis is very common; it is estimated to affect almost one in four adults, particularly elderly patients.
Severity Scores in Children With Acute Pancreatitis
Authors: Fabre Alexandre , Petit Philippe , Gaudart Jean , Mas Emmanuel , Vial Julie , Olives Jean‐Pierre , Sarles Jacques
Published: March 2012

Severity scores are used to predict the outcome of acute pancreatitis (AP). Several scores are used in adult patients, but none has been thoroughly validated for specific use in paediatric patients. We retrospectively collected data from 48 children with AP (13 severe and 35 mild). The main causes were trauma (23%), idiopathic (23%), lithiasis (12.5%), and virus (10.5%). We evaluated 3 clinical scores (Ranson, Glasgow modified, and DeBanto) and Balthazar computed tomography severity index. The clinical scores had a good specificity (approximately 85%) but a low sensitivity (approximately 55%) in predicting the severity of paediatric AP. The radiological score is better (sensitivity 80%, specificity 86%). The area under the receiver operator characteristic curve was 0.699 (95% CI 0.508%–0.891%, P = 0.054) for the DeBanto score, 0.846 (95% CI 0.69%–1%, P = 0.001) for the Ranson score, and 0.774 (95% CI 0.584%–0.964%, P = 0.008) for the Glasgow and 0.898 (95% CI 0.73%–1%, P = 0.011) for the Balthazar computed tomography severity index score. In our paediatric cohort, the severity of AP was best predicted by Balthazar computed tomography–based scoring scale. Our results confirm previously reported low sensitivity of adult‐based clinical scoring scales.
Social learning of a communicative signal in captive chimpanzees
Authors: Taglialatela Jared P. , Reamer Lisa , Schapiro Steven J. , Hopkins William D.
Published: March 2012

The acquisition of linguistic competency from more experienced social partners is a fundamental aspect of human language. However, there is little evidence that non-human primates learn to use their vocalizations from social partners. Captive chimpanzees (
Pan troglodytes
) produce idiosyncratic vocal signals that are used intentionally to capture the attention of a human experimenter. Interestingly, not all apes produce these sounds, and it is unclear what factors explain this difference. We tested the hypothesis that these attention-getting (AG) sounds are socially learned via transmission between mothers and their offspring. We assessed 158 chimpanzees to determine if they produced AG sounds. A significant association was found between mother and offspring sound production. This association was attributable to individuals who were raised by their biological mother—as opposed to those raised by humans in a nursery environment. These data support the hypothesis that social learning plays a role in the acquisition and use of communicative vocal signals in chimpanzees.