bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy constraint beaconing control in delay tolerant networks with multiple destinations
Authors: Wu Yahui , Deng Su , Huang Hongbin
Published: June 2014

Message dissemination in delay tolerant networks (DTN) closely depends on the opportunistic contact between nodes. However, the contact is related to the beaconing rate of nodes. In particular, the node has more chances to contact with others if it has bigger beaconing rate, but this will need more energy. In this paper, we study the optimal beaconing policy in DTN with limited energy. In particular, we focus on the case with multiple destinations. According to whether the destinations forward the message to others, we explore the non‐replicative and replicative cases, respectively. First, we introduce a theoretical model for each case, which can be used to evaluate the performance under different beaconing rates. Then, based on these models, we present the corresponding optimization problems. Through Pontryagin's Maximal Principle, we obtain the optimal beaconing rate and prove that the optimal policies conform to the threshold form in both cases. Simulations show the accuracy of our theoretical models. Extensive numerical results show that the performance of the replicative case is better when the energy is limited. Copyright © 2014 John Wiley & Sons, Ltd.
CSMA/CA‐based medium access control for indoor millimeter wave networks
Authors: Qiao Jian , Shen Xuemin (Sherman) , Mark Jon W. , Cao Bin , Shi Zhiguo , Zhang Kuan
Published: June 2014

Millimeter wave (mmWave) communication is a promising technology to support high‐rate (e.g., multi‐Gbps) multimedia applications because of its large available bandwidth. Multipacket reception is one of the important capabilities of mmWave networks to capture a few packets simultaneously. This capability has the potential to improve medium access control layer performance. Because of the severe propagation loss in mmWave band, traditional backoff mechanisms in carrier sensing multiple access/collision avoidance (CSMA/CA) designed for narrowband systems can result not only in unfairness but also in significant throughput reduction. This paper proposes a novel backoff mechanism in CSMA/CA by giving a higher transmission probability to the node with a transmission failure than that with a transmission success, aiming to improve the system throughput. The transmission probability is adjusted by changing the contention window size according to the congestion status of each node and the whole network. The analysis demonstrates the effectiveness of the proposed backoff mechanism on reducing transmission collisions and increasing network throughput. Extensive simulations show that the proposed backoff mechanism can efficiently utilize network resources and significantly improve the network performance on system throughput and fairness. Copyright © 2014 John Wiley & Sons, Ltd.
Investigations of the superlubricity of sapphire against ruby under phosphoric acid lubrication
Authors: Li Jinjin , Zhang Chenhui , Deng Mingming , Luo Jianbin
Published: June 2014

In this study, we address the superlubricity behavior of sapphire against ruby (or sapphire against itself) under phosphoric acid solution lubrication. An ultra-low friction coefficient of 0.004 was obtained under a very high contact pressure, with a virgin contact pressure up to 2.57 GPa. Related experiments have indicated that the load, sliding speed, and humidity of the test environment can affect superlubricity to some degree, so we tested variations in these conditions. When superlubricity appears in this study a thin film is present, consisting of a hydrogen bond network of phosphoric acid and water molecules adsorbed on the two friction surfaces, which accounts for the ultra-low friction. Most significantly, the wear rate of the sapphire and ruby in the friction process is very slow and the superlubricity state is very stable, providing favorable conditions for future technological applications.
High-elevation paleoenvironmental change during MIS 6–4 in the central Rockies of Colorado as determined from pollen analysis
Authors: Anderson R. Scott , Jiménez-Moreno Gonzalo , Ager Thomas , Porinchu David F.
Published: June 2014

Paleoecological studies from Rocky Mountain (USA) high elevations encompassing the previous interglacial (MIS 5e) are rare. The ~10-m composite profile from the Ziegler Reservoir fossil site (2705 m asl) of central Colorado allows us to determine paleoenvironments from Marine Oxygen Isotope Stages (MIS) 6– 4 using pollen zones that are approximately equivalent to marine oxygen isotope stages. During Pollen Zone (PZ) 6 time, pollen assemblages dominated by Artemisia (sagebrush) suggest that alpine tundra or steppe occurred nearby. The transition to PZ 5e was characterized by a rapid increase in tree pollen, initially Picea (spruce) and Pinus (pine) but also Quercus (oak) and Pseudotsuga menziesii (Douglas-fir). Non-arboreal pollen (NAP) types increased during PZ 5d, while Abies (fir) and Juniperus (juniper) increased during PZ 5c. Pollen evidence suggests that temperatures during PZ 5b were as cold as during PZ 6, with the site again surrounded by alpine tundra. Picea dominated during PZ 5a before the onset of cooler conditions during PZ 4. The MIS 6–MIS 5e transition here was similar to the MIS 2–MIS 1 transition at other Rocky Mountain sites. However, the Ziegler Reservoir pollen record contains evidence suggesting unexpected climatic trends at this site, including a warmer-than-expected MIS 5d and cooler-than-expected MIS 5b.
When the smoke clears: expertise, learning and policy diffusion
Authors: Shipan Charles R. , Volden Craig
Published: June 2014

In federal systems, governments have the opportunity to learn from the policy experiments – and the potential successes – of other governments. Whether they seize such opportunities, however, may depend on the expertise or past experiences of policymakers. Based on an analysis of state-level adoptions of antismoking restrictions targeted towards youths, we find that US states are more likely to emulate other states that have demonstrated the ability to successfully limit youth smoking. In addition, we find that political expertise (as captured by legislative professionalism) and policy expertise (as captured by previous youth access policy experiments at the local level) enhance the likelihood of emulating policy successes found in other states. As such, we establish that internal expertise and external learning are complements, rather than substitutes.
Replication research in comparative genre analysis in English for Academic Purposes
Authors: Basturkmen Helen
Published: June 2014

In recent years a number of comparative studies based on an established approach to genre analysis have been published in the English for Academic Purposes (EAP) literature. Studies in this emerging strand of research typically aim to identify how the rhetorical structure of a particular genre (a text type) or part of a genre may vary across different disciplines or groups of writers. The first part of this article makes a case for replication in this strand of research, arguing that replication would be timely and suggesting the advantages that it could offer to the field of EAP. The second part focuses on three key studies, and suggests how each one might be replicated and the potential benefits of doing so.
Research in the School of Languages and Linguistics at Griffith University
Authors: Fenton-Smith Ben , Walkinshaw Ian
Published: June 2014

Griffith University is set across five campuses in south-east Queensland, Australia, and has a student population of 43,000. The School of Languages and Linguistics (LAL) offers programs in linguistics, international English, Chinese, Italian, Japanese and Spanish, as well as English language enhancement courses. Research strands reflect the staff's varied scholarly interests, which include academic language and learning, sociolinguistics, second language learning/acquisition and teaching, computer assisted language learning (CALL) and language corpora. This report offers a summary of research recently published or currently underway within LAL.
Dynamic modeling and parameter estimation for traction, rolling, and lateral wheel forces to enhance mobile robot trajectory tracking
Authors: Bayar Gokhan , Koku A. Bugra , Konukseven E. Ilhan
Published: June 2014

Studying wheel and ground interaction during motion has the potential to increase the performance of localization, navigation, and trajectory tracking control of a mobile robot. In this paper, a differential mobile robot is modeled in a way that (traction, rolling, and lateral) wheel forces are included in the overall system dynamics. Lateral wheel forces are included in the mathematical model together with traction and rolling forces. A least square parameter estimation process is proposed to estimate the parameters of the wheel forces. In order to implement the proposed methodologies, an experimental setup is used. The setup contains a differentially driven mobile robot, a specially constructed test surface, and a camera system attached at the top of surface for obtaining ground truth. Models having one or more wheel forces are simulated to find the most realistic model. Simulation results are verified by experiments.
General practitioners’ beliefs about the clinical utility of complementary and alternative medicine
Authors: Jarvis Aron , Perry Rachel , Smith Debbie , Terry Rohini , Peters Sarah
Published: June 2014

Aim

To investigate GPs’ beliefs about complementary and alternative medicine (CAM) and its role in clinical practice.

Background

Despite the prevalence of CAM in the United Kingdom, little is known about GPs beliefs regarding these alternative approaches to patient management and how they view it in relation to their clinical conduct and practice.

Method

A qualitative study conducted on 19 GPs recruited from the North West of England. Semi-structured telephone interviews were analysed using an inductive thematic analysis.

Results

Three themes emerged from the data: limited evidence base, patient demand and concerns over regulation.

Conclusion

Despite recognising the limited evidence base of CAM, GPs continue to see a role for it within clinical practice. This is not necessarily led by patient demand that is highly related to affluence. However, GPs raised concerns over the regulation of CAM practitioners and CAM therapies.
MMIC-based asymmetric Doherty power amplifier for small cells applications
Authors: Moronval Xavier , Abdoelgafoer Reza , Déchansiaud Adeline
Published: June 2014

We present the results obtained on a multi-mode multi-band 20 W Monolithic Microwave Integrated Circuit (MMIC) power amplifier. The proposed two-stage circuit is based on the silicon Laterally Diffused Metal Oxide Semiconductor (LDMOS) technology. Thanks to dedicated design techniques, it can cover the Digital Cellular Service (DCS), Personal Communications Service (PCS), and UMTS bands (ranging from 1.805 to 2.17 GHz) and deliver more than 20 W of output power, 30 dB of gain and 50% of power added efficiency. When combined in a Doherty configuration with an incremental 40 W MMIC in a dual-path package, the resulted asymmetric MMIC (an industry first) can deliver an unprecedented LDMOS MMIC efficiency of up to 44% at 8 dB back-off in the UMTS band. Then, the DPA has been optimized in conjunction with a novel RF pre-distortion technique, leading to 33–80% energy saving at the system level.
Identification of in vivo components in rats after oral administration of lotus leaf flavonoids using ultra fast liquid chromatography with tandem mass spectrometry
Authors: Ye Lin-Hu , He Xiao-Xi , Yan Ming-Zhu , Chang Qi
Published: June 2014

The herb of lotus (Nelumbo nucifera) leaves is the traditional Chinese medicine He Ye, which is commonly used to treat sunstroke, assuage thirst, and cure both diarrhea and fever in China.
Analysis of six bioactive components in Semen Ziziphi Spinosae by UPLC-ELSD and UPLC-Q/TOF-MS
Authors: Zhao Xiangsheng , Xie Liwei , Wu Haifeng , Kong Weijun , Yang Meihua
Published: June 2014

A fast and validated multicomponent analytical method was developed based on ultrasonic extraction, detection by UPLC-ELSD and confirmation by UPLC-Q/TOF-MS.
13C NMR investigations and the molecular order of 4-(trans-4′-hexylcyclohexyl)-isothiocyanatobenzene (6CHBT)
Authors: Lobo Nitin P. , Phani Kumar B. V. N. , Narasimhaswamy T. , Mandal Asit Baran
Published: June 2014

13C NMR and 2D SLF investigations provide atomistic level information on the nematogen 6CHBT, utilized for probing the molecular order.
ZnO–Ag hybrids for ultrasensitive detection of trinitrotoluene by surface-enhanced Raman spectroscopy
Authors: He Xuan , Wang Hui , Li Zhongbo , Chen Dong , Zhang Qi
Published: June 2014

Low-cost SERS sensors were fabricated by 4-ATP-functionalized ZnO–Ag hybrid substrates for TNT detection with high sensitivity, selectivity and reproducibility.
NMR-based metabolomics approach to study the chronic toxicity of crude ricin from castor bean kernels on rats
Authors: Guo Pingping , Wang Junsong , Dong Ge , Wei Dandan , Li Minghui , Yang Minghua , Kong Lingyi
Published: June 2014

NMR based metabolomics approach combined with OSC-PLSDA was applied to investigate the chronic toxicity of crude ricin from castor bean kernels on rats for the first time.
Synthesis of polymeric lubricating films directly at the sliding interface via mechanochemical reactions of allyl alcohols adsorbed from the vapor phase
Authors: Barthel Anthony J. , Combs Daniel R. , Kim Seong. H.
Published: June 2014

Friction initially occurs in a vapor environment, during which a triboproduct is formed. This triboproduct lubricates in absence of the vapor for over 30 000 reciprocating cycles.
Relaxation is the key to longer life: suppressed degradation of P3HT films on conductive substrates
Authors: Zhao Yichen , Sugunan Abhilash , Schmidt Torsten , Fornara Andrea , Toprak Muhammet S. , Muhammed Mamoun
Published: June 2014

P3HT degradation is shown to be suppressed when it is on conductive substrates. This ‘substrate effect’ is more significant than maintaining an inert environment.
Coordination-resolved local bond relaxation and electron binding-energy shift of Pb solid skins and atomic clusters
Authors: Bo Maolin , Wang Yan , Huang Yongli , Zhou Wei , Li Can , Sun Chang Q.
Published: June 2014

Lead (Pb) demonstrates pronounced energy states pertaining to undercoordinated skin and edge atoms.
Recombinant form of mammalian gp91phox is active in the absence of p22phox
Authors: Ezzine Aymen , Souabni Hager , Bizouarn Tania , Baciou Laura
Published: June 2014

The flavocytochrome b558 of the phagocyte NADPH oxidase complex comprises two membrane proteins, a glycosylated gp91phox and a non-glycosylated p22phox. Gp91phox contains all of the redox carriers necessary to reduce molecular oxygen to superoxide using NADPH. The capacity of gp91phox to produce superoxide in the absence of its membrane partner p22phox has been little studied. In the present study, we have generated in Pichia pastoris for the first time an active form of bovine gp91phox able to carry out the entire NADPH oxidase activity in the absence of p22phox. Collected information on the maturation and the activity of the recombinant gp91phox and the participation of individual cytosolic subunits in the active complex allowed us to propose, in the absence of p22phox, an unconventional stabilized complex compared with the heterodimer.
Physical ischaemia induced by isometric exercise facilitated collateral development in the remote ischaemic myocardium of humans
Authors: Lin Song , Chen Yan , Li Yongxue , Li Jianan , Lu Xiao
Published: June 2014

The aim of the present study was to investigate the effects of isometric-handgrip-induced PIT (physical ischaemia training) on remote coronary recruitment and growth. A total of 74 CAD (coronary artery disease) patients were randomly assigned to either the IHG (isometric handgrip group) or NEG (non-exercise group). Patients in the IHG performed isometric handgrip exercises during 1 min of coronary balloon occlusion, whereas patients in the NEG remained sedentary. CFI (collateral flow index), HR (heart rate), SBP (systolic blood pressure) and DBP (diastolic blood pressure) were evaluated before and at the end of occlusion. In a second study, 21 CAD patients were randomly divided into the IHT (isometric handgrip training) group or the NTG (non-training group). Patients in the IHT group performed 3 months of IHT, whereas patients in the control group remained sedentary. SPECT (single-photon emission computed tomography) was used to evaluate myocardial perfusion, and VEGF (vascular endothelial growth factor) levels were determined using ELISA. In the IHG, CFI was significantly higher than in the control group (P<0.01). HR, SBP and DBP in the IHG were significantly higher than in the NEG (P<0.01) at the end of occlusion. In the second study, myocardial perfusion (P<0.05) and left ventricular ejection fraction (P<0.01) were significantly improved in the IHT group. VEGF levels in the IHT group were significantly increased (P<0.01). Levels of VEGF were negatively correlated with the summed rest score of SPECT (r=−0.60, P<0.01). In conclusion, isometric handgrip exercise-induced PIT may promote remote collateral recruitment and growth in CAD patients.
Study on an interleaved buck power factor corrector with gallium nitride field effect transistor and integrated inductor
Authors: Lin Chien‐Yu , Liu Yu‐Chen , Chiu Huang‐Jen , Lo Yu‐Kang , Lin Chung‐Yi , Tseng Po‐Jung , Cheng Shih‐Jen
Published: June 2014

In this study, a buck power factor corrector (PFC) with gallium nitride field effect transistor (GaN FET) and integrated inductor is studied. An interleaved constant‐frequency clamped‐current control method is adopted to achieve high power factor, low input and output current ripples as well as high efficiency. Two inductors in the studied interleaved buck PFC are integrated to reduce the core loss. A 300 W/80 V laboratory prototype with 300 kHz switching frequency was built and tested under universal input voltage conditions. Experimental results are shown to verify the performance of the studied converter. According to the experimental verifications, the efficiency can reach higher than 95% from 10 to 100% load variations at 115 V input. The measured input current harmonic can meet with the IEC 61000‐3‐2 Class D standard.
METAMORPHOSE VI – the Virtual Institute for artificial electromagnetic materials and metamaterials: origin, mission, and activities
Authors: Bilotti Filiberto , Rockstuhl Carsten , Schuchinsky Alex , Tretyakov Sergei
Published: June 2014

In this paper, we outline the background, mission, and activities of the Virtual Institute for Artificial Electromagnetic Materials and Metamaterials (METAMORPHOSE VI). This international association, founded in the framework of the FP-6 Network of Excellence METAMORPHOSE, aims at promoting and developing research, training, and dissemination activities in the emerging and highly dynamic field of advanced electromagnetic materials and metamaterials at both European and International levels. More than 300 researchers are currently associated with the METAMORPHOSE VI which networks them together in a learnt society. After a brief description of the association and its mission, we present an overview of the activities developed by the METAMORPHOSE VI, with a particular emphasis on the coordination of the European Doctoral Program on Metamaterials (EUPROMETA) and the organization of the International Congress on Advanced Electromagnetic Materials in Microwaves and Optics – metamaterials congress.
Low-temperature operational regime of an adiabatic Brownian motor
Authors: Rozenbaum V. M.
Published: June 2014

The motion of a Brownian particle in two cyclically-switching spatially-periodic asymmetric potentials with the cycle period longer than the relaxation time is considered. It is shown that at low temperatures a directed movement occurs in the case when the positions of the absolute maxima and minima of the two switching potentials alternate or an asymmetric potential is cyclically switched ON and OFF. The obtained results elucidate the role of diffusion processes and force effects arising from the potential switching in the operational mechanisms of Brownian motors.
Many-particle quantum graphs and Bose-Einstein condensation
Authors: Bolte Jens , Kerner Joachim
Published: June 2014

In this paper, we propose quantum graphs as one-dimensional models with a complex topology to study Bose-Einstein condensation and phase transitions in a rigorous way. We first investigate non-interacting many-particle systems on quantum graphs and provide a complete classification of systems that exhibit Bose-Einstein condensation. We then consider models of interacting particles that can be regarded as a generalisation of the well-known Tonks-Girardeau gas. Here, our principal result is that no phase transitions occur in bosonic systems with repulsive hardcore interactions, indicating an absence of Bose-Einstein condensation.
Solitons and freak waves in a mixed nonextensive high energy-tail electron distribution
Authors: Bouzit Omar , Gougam Leila Ait , Tribeche Mouloud
Published: June 2014

Weak ion acoustic (IA) solitary waves are investigated in a mixed nonextensive high energy-tail electron distribution, focusing on the influence of an interplay between nonthermality and nonextensivity on the IA soliton nature, its carried energy and associated rogue waves. The IA soliton exhibits compression or rarefaction depending on the strength of nonextensivity and the amount of nonthermality. The latter favors the development of rarefactive solitary structures, i.e., their corresponding q-interval enlarges as α increases. In a pure nonextensive plasma (α = 0), the energy carried by the IA soliton first decreases with q before increasing beyond a local minimum. The latter is shifted toward higher values of the nonextensive parameter q as α is increased. Moreover, nonthermal effects may render stronger the associated IA rogue waves.
Lifting the off-state bandgap limit in InAs channel metal-oxide-semiconductor heterostructures of nanometer dimensions
Authors: Passlack Matthias , Wang Shih-Wei , Doornbos Gerben , Wang Chien-Hsun , Contreras-Guerrero Rocio , Edirisooriya Madhavie , Rojas-Ramirez Juan , Hsieh Chih-Hua , Droopad Ravi , Diaz Carlos H.
Published: June 2014

One of the major challenges of high mobility complementary metal-oxide-semiconductor (CMOS) circuits is to meet off-current requirements of <100 pA/μm for low stand-by power (LSTP) operation due to the small bandgap (≤0.5 eV) of the channel material (bandgap limit). In this work, we present experimental proof that the bandgap limit can be overcome at nanometer dimensions leveraging the phenomenon of steady state deep depletion (SSDD). The occurrence of SSDD is investigated using high-k capacitors with 5 and 10 nm InAs channel on a n- or p-type doped lattice matched wide bandgap AlAsSb layer. Absence of charge carriers at the off-state band edge is observed for 5 nm InAs channel layers demonstrating occurrence of SSDD and lifting of the off-state bandgap limit providing a path to meet LSTP requirements for future high mobility CMOS.
A graphene nanoribbon neuro-sensor for glycine detection and imaging
Authors: Hossain Faruque M. , Al-Dirini Feras , Skafidas Efstratios
Published: June 2014

Glycine acts as a neurotransmitter in the Central Nervous System (CNS) and plays a vital role in processing of motor and sensory information that control movement, vision, and audition. Glycine detection and imaging can lead to a greater understanding of how this information is processed in the CNS. Here, we present a neuro-sensor for the detection and imaging of Glycine molecules, based on a zigzag Graphene Nanoribbon device structure. An energetically stable Nitrogen Vacancy (NV) center is introduced in the device to enable its use in neuronal imaging applications. We demonstrate, by using the Density Functional Theory and Nonequilibrium Green's Function method, that the device detects the attachment of a single Glycine molecule to its edges by significant changes in its conductance. The attachment of Glycine induces current channels around the NV center increasing the current flow through the device. In absence of Glycine, the presence of the NV center suppresses current flow through the device, significantly reducing its power consumption, and allowing for its use in proximity of living neuron cells.
Raman spectroscopic study of the size-dependent order parameter of barium titanate
Authors: Sendova Mariana , Hosterman Brian D.
Published: June 2014

Spherical barium titanate nanoparticles, having a diameter of 50–500 nm, were characterized using micro-Raman spectroscopy at 83 K. Proposed is a calibrated intensity method allowing a spectroscopic estimate of the relative fraction of two solid-state structural phases, where the phases have uniquely identifiable Raman bands. The Raman spectroscopy local probe is broadened to quantify macroscopic characteristics, such as the order parameter. Based on the intensity of the 311 cm−1 mode, it is revealed that the order parameter, η, of BaTiO3 decreases exponentially with particle size reduction. Similarly, an exponential decrease of the long-range (dipole-dipole) interaction is suggested, based on the Raman shift of the 716 cm−1 mode. An approximate long-range interaction decrease of 3% is estimated when the particle size is reduced from 500 nm to 50 nm. This study provides evidence that BaTiO3 nanoparticles can be modeled as being composed of coexisting cubic and non-cubic phases with relative fraction controlled by the degree of long-range Coulombic interactions.
Multiferroic BiFeO3 glass-ceramics: Phase formation and physical property
Authors: Takahashi Yoshihiro , Meguro Kousuke , Naganuma Hiroshi , Terakado Nobuaki , Fujiwara Takumi
Published: June 2014

A production of polycrystalline phase with glassy precursor, i.e., glass-ceramics processing, has a great potential to fabricate the sophisticated materials. In this study, we have prepared the Bi2O3–Fe2O3–BaO–B2O3 system precursor, in which BiFeO3 phase is crystallizable, and examined the phase formation and physical properties in resulting glass-ceramics. We found both ferroelectricity and ferromagnetism in the glass-ceramics consisting of BiFeO3 phase, i.e., multiferroic glass-ceramics. This study has demonstrated an alternative method for synthesis of polycrystalline BiFeO3 material.
On electronic structure of polymer-derived amorphous silicon carbide ceramics
Authors: Wang Kewei , Li Xuqin , Ma Baisheng , Wang Yiguang , Zhang Ligong , An Linan
Published: June 2014

The electronic structure of polymer-derived amorphous silicon carbide ceramics was studied by combining measurements of temperature-dependent conductivity and optical absorption. By comparing the experimental results to theoretical models, electronic structure was constructed for a carbon-rich amorphous silicon carbide, which revealed several unique features, such as deep defect energy level, wide band-tail band, and overlap between the band-tail band and defect level. These unique features were discussed in terms of the microstructure of the material and used to explain the electric behavior.
Enhanced visible photoluminescence emission from multiple face-contact-junction ZnO nanorods coated with graphene oxide sheets
Authors: Ding Jijun , Wang Minqiang
Published: June 2014

Multiple face-contact-junction ZnO nanorods (MFCJ ZnO NRs) coated with graphene oxide (GO) sheets have been realized on indium tin oxide substrates. The coated amount and thickness of GO on MFCJ ZnO NRs can be adjusted by electrodeposition time. Photoluminescence (PL) properties of MFCJ ZnO NRs coated with GO sheets are measured and found to be strongly depended on the electrodeposition time of GO sheets. The strongest visible PL emission with the appropriate GO electrodeposition time is observed. We proposed that, in this case, the surface of MFCJ ZnO NRs is coated by very thin GO sheets with ionized oxygen functional species that trap conduction electrons, causing ZnO energy band bending at the surface, which accumulates the surface charges within a very thin surface layer. The charges in surface layer transition to impurities levels cause an enhanced visible PL emission in MFCJ ZnO NRs.
Solvent-induced surface state passivation reduces recombination in semisquarylium dye-sensitized solar cells
Authors: Bartelt Andreas F. , Schütz Robert , Strothkämper Christian , Kastl Ivo , Janzen Stephan , Friedrich Dennis , Calvet Wolfram , Fuhrmann Gerda , Danner David , Scheller Lars-Peter , Nelles Gabriele , Eichberger Rainer
Published: June 2014

The semisquarylium dye SY1T that is strongly bound to the surface of nanocrystalline TiO2 experiences very fast back-electron transfer of injected electrons to the SY1T cation, when the TiO2/SY1T interface is surrounded by ultrahigh vacuum. However, when located in methoxypropionitrile (MPN), which is frequently used as electrolyte solvent in dye-sensitized solar cells, the back-electron transfer is significantly retarded. Results are obtained both for picosecond and microsecond time scales using transient absorption spectroscopy. As solvent-induced interfacial energy level shifts can be excluded as possible cause, the role of TiO2 surface states in the beneficial retardation process is investigated. Highly surface sensitive synchrotron-induced photoelectron spectroscopy exhibits high densities of surface states on the pristine nanocrystalline TiO2 (nc-TiO2) surfaces. While SY1T dye-sensitization from a SY1T solution in tetrahydrofuran saturates about 30% of the surface states, the subsequent in-situ adsorption of MPN molecules at the TiO2/SY1T interface leads to further reduction by more than 50% of the remaining surface states. It is concluded that the saturation of TiO2 surface states hampers the otherwise efficient recombination of injected electrons with the SY1T dye cation.
Analyzing carrier escape mechanisms in InAs/GaAs quantum dot p-i-n junction photovoltaic cells
Authors: Sellers D. G. , Polly S. , Hubbard S. M. , Doty M. F.
Published: June 2014

Intermediate band solar cells (IBSCs) are third-generation photovoltaic (PV) devices that can harvest sub-bandgap photons normally not absorbed in a single-junction solar cell. Despite the large increase in total solar energy conversion efficiency predicted for IBSC devices, substantial challenges remain to realizing these efficiency gains in practical devices. We evaluate carrier escape mechanisms in an InAs/GaAs quantum dot intermediate band p-i-n junction PV device using photocurrent measurements under sub-bandgap illumination. We show that sub-bandgap photons generate photocurrent through a two-photon absorption process, but that carrier trapping and retrapping limit the overall photocurrent. The results identify a key obstacle that must be overcome in order to realize intermediate band devices that outperform single junction photovoltaic cells.
A scaling law for the dust cloud in radio frequency discharge under microgravity conditions
Authors: Zhukhovitskii D. I. , Molotkov V. I. , Fortov V. E.
Published: June 2014

We employ the approximation of overlapped scattering potentials of charged dust particles exposed to streaming ions to deduce the “equation of state” for a stationary dust cloud in the radio frequency discharge apart from the void-dust boundary. The obtained equation defines the potential of a dust particle as a function of the ion number density, the mass of a carrier gas atom, and the electron temperature. A scaling law that relates the particle number density to the particle radius and electron temperature in different systems is formulated. Based on the proposed approach, the radius of a cavity around a large particle in the bulk of a cloud is estimated. The results of calculation are in a reasonable agreement with the experimental data available in literature.
Functionalised 1-Alkynylarsines: Synthesis, Characterisation, and Attempts of Rearrangement into Functionalised Arsaalkynes
Authors: Baba Gnon , Guillemin Jean-Claude
Published: June 2014

Functionalised 1-alkynylarsines were synthesised by reaction of the corresponding 1-alkynyltributylstannane on arsenic trichloride followed by chemoselective reduction of the formed 1-alkynyldichloroarsine by tributyltin hydride in the presence of small amounts of a radical inhibitor. Rearrangements of these compounds into the corresponding arsaalkynes were attempted.
Pruning of memories by context-based prediction error
Authors: Kim Ghootae , Lewis-Peacock Jarrod A. , Norman Kenneth A. , Turk-Browne Nicholas B.
Published: June 2014

Significance

Forgetting is often considered to be bad, but selective forgetting of unreliable information can have the positive side effect of reducing mental clutter, thereby making it easier to access our most important memories. Prior studies of forgetting have focused on passive mechanisms (decay, interference) or on effortful inhibition by cognitive control. Here we report the discovery of an active mechanism for forgetting that weakens memories selectively and without burdening the conscious mind. Specifically, we show that the brain automatically generates predictions about which items should appear in familiar contexts; if these items fail to appear, their memories are weakened. This process is adaptive, because such memories may have been encoded incorrectly or may represent unstable aspects of the world.
Engineering of a red-light–activated human cAMP/cGMP-specific phosphodiesterase
Authors: Gasser Carlos , Taiber Sandra , Yeh Chen-Min , Wittig Charlotte Helene , Hegemann Peter , Ryu Soojin , Wunder Frank , Möglich Andreas
Published: June 2014

Significance

Sensory photoreceptors not only enable organisms to derive spatial and temporal cues from incident light but also provide the basis for optogenetics, which denotes the manipulation by light of living systems with supreme spatial and temporal resolution. To expand the scope of optogenetics, we have engineered the light-activated phosphodiesterase LAPD, which degrades the ubiquitous second messengers cAMP and cGMP in a red-light–stimulated manner. Both cAMP and cGMP are key to the regulation of manifold physiological responses, and LAPD now augurs red-light control over these processes. As we demonstrate for two eukaryotic systems, LAPD does not require any additional exogenous factors, and thus permits the light perturbation of living cells in hitherto unrealized ways.
Manganese-enhanced magnetic resonance imaging reveals increased DOI-induced brain activity in a mouse model of schizophrenia
Authors: Malkova Natalia V. , Gallagher Joseph J. , Yu Collin Z. , Jacobs Russell E. , Patterson Paul H.
Published: June 2014

Significance

Here, we model a positive symptom of schizophrenia, hallucination-like activity, in a mouse model of an environmental risk factor of schizophrenia, maternal immune activation (MIA). MIA offspring display an enhanced susceptibility to the hallucinogen 2,5-dimethoxy-4-iodoamphetamine (DOI) and demonstrate elevated DOI-induced brain activity as measured by induction of immediate early genes and manganese-enhanced MRI. High sensitivity to DOI in MIA offspring can be explained by an increased level of serotonin receptor 2A (5-HT2AR) that mediates the effect of DOI on the prefrontal cortex. Chronic treatment with the 5-HT2AR antagonist ketanserin reduces DOI-induction of head twitching in MIA offspring. Our data demonstrate that DOI-induced hallucination-like activity can be modeled in the MIA mouse model and suggest 5-HT2AR as a potential therapeutic target for schizophrenia.
Pathway for Mn-cluster oxidation by tyrosine-Z in the
S
2
state of photosystem II
Authors: Narzi Daniele , Bovi Daniele , Guidoni Leonardo
Published: June 2014

Significance

A key step in natural photosynthesis is the water-splitting reaction into molecular oxygen and hydrogen equivalents. Understanding the molecular mechanisms behind this photoreaction will unravel the secrets of solar energy conversion in biochemistry and may inspire the design of artificial biomimetic materials for green energy production. Photosynthetic water oxidation occurs in the Mn
4
Ca core of the photosystem II complex and proceeds through five subsequent steps
S
0
–
S
4
of the Kok cycle. Four electrons are sequentially removed from the Mn
4
Ca core by a nearby tyrosine, which is in turn oxidized by the photoactivated chlorophyll special pair. Using first principles multiscale atomistic simulations we clarify the thermodynamics and the kinetics for such electron abstraction in the
S
2
state.
Water-mediated ion–ion interactions are enhanced at the water vapor–liquid interface
Authors: Venkateshwaran Vasudevan , Vembanur Srivathsan , Garde Shekhar
Published: June 2014

Significance

Developing a framework for understanding self-assembly at aqueous interfaces requires the knowledge of how interfaces affect ionic and hydrophobic interactions in their vicinity. We use molecular simulations to focus on ion–ion interactions at the water vapor–liquid interface. We show that the effective forces between small ions change character dramatically near the interface, whereas oppositely charged ions attract each other more strongly than in bulk water and like-charged ions repel less strongly and can even attract each other when drawn to the vapor side of the interface. Our results suggest that water-mediated electrostatic interactions may play an even more important role in biological and colloidal assembly at soft aqueous interfaces compared with that in bulk.
Mutations disrupting the Kennedy phosphatidylcholine pathway in humans with congenital lipodystrophy and fatty liver disease
Authors: Payne Felicity , Lim Koini , Girousse Amandine , Brown Rebecca J. , Kory Nora , Robbins Ann , Xue Yali , Sleigh Alison , Cochran Elaine , Adams Claire , Dev Borman Arundhati , Russel-Jones David , Gorden Phillip , Semple Robert K. , Saudek Vladimir , O’Rahilly Stephen , Walther Tobias C. , Barroso Inês , Savage David B.
Published: June 2014

Significance

The characterization of rare monogenic human disorders can and has yielded unique biological insights. Our phenotypic description and functional characterization of human loss-of-function mutations in
PCYT1A
is both clinically important for patients and their families afflicted with this rare but serious metabolic disease and biologically helpful in advancing understanding of the physiological consequences of impaired PCYT1A activity in humans.
Photoinduced transformations of stiff-stilbene-based discrete metallacycles to metallosupramolecular polymers
Authors: Yan Xuzhou , Xu Jiang-Fei , Cook Timothy R. , Huang Feihe , Yang Qing-Zheng , Tung Chen-Ho , Stang Peter J.
Published: June 2014

Significance

Coordination-driven self-assembly is a synthetic method used to generate complex structures based on the simple formation of metal–ligand bonds between molecular building blocks. These building blocks can be functionalized in a variety of ways, endowing the process with a wide range of modularity and tunability. Here, a building block is used that changes its structure when it absorbs light. Because the geometry of each building block is a critical determinant of overall structure, when the precursor changes its shape the final assembly transforms from a discrete metallacycle to an extended 1D network. This technique demonstrates that coordination-driven self-assembly can be used to obtain dynamic materials that respond to external stimuli.
Actin and dynamin2 dynamics and interplay during clathrin-mediated endocytosis
Authors: Grassart Alexandre , Cheng Aaron T. , Hong Sun Hae , Zhang Fan , Zenzer Nathan , Feng Yongmei , Briner David M. , Davis Gregory D. , Malkov Dmitry , Drubin David G.
Published: June 2014

Clathrin-mediated endocytosis (CME) involves the recruitment of numerous proteins to sites on the plasma membrane with prescribed timing to mediate specific stages of the process. However, how choreographed recruitment and function of specific proteins during CME is achieved remains unclear. Using genome editing to express fluorescent fusion proteins at native levels and live-cell imaging with single-molecule sensitivity, we explored dynamin2 stoichiometry, dynamics, and functional interdependency with actin. Our quantitative analyses revealed heterogeneity in the timing of the early phase of CME, with transient recruitment of 2–4 molecules of dynamin2. In contrast, considerable regularity characterized the final 20 s of CME, during which ∼26 molecules of dynamin2, sufficient to make one ring around the vesicle neck, were typically recruited. Actin assembly generally preceded dynamin2 recruitment during the late phases of CME, and promoted dynamin recruitment. Collectively, our results demonstrate precise temporal and quantitative regulation of the dynamin2 recruitment influenced by actin polymerization.
Conductance and Fano factor in normal/ferromagnetic/normal bilayer graphene junction
Authors: Rashidian Z , Mojarabian F M , Bayati P , Rashedi G , Ueda A , Yokoyama T
Published: June 2014

We theoretically investigate the transport properties of bilayer graphene junctions, where the ferromagnetic strips are attached to the middle region of the graphene sheet. In these junctions, we can control the band gap and the band structure of the bilayer graphene by using the bias voltage between the layers and the exchange field induced on the layers. The conductance and Fano factor (F ) are calculated by the Landauer–Büttiker formula. It is found that when the voltage between the layers or the exchange field are tuned, the pseudodiffusive (F = 1/3) transport turns into tunneling (F = 1) or ballistic transport (F = 0). By tuning the potential difference between the layers, one can control the spin polarization of the current.
Cognitive Processes in Musical Improvisation
Authors: Dean Roger T. , Bailes Freya
Published: June 2014

This chapter discusses the conceptual frameworks in which current empirical studies of cognition in musical improvisation are being undertaken. It takes as its starting point the significant theoretical and empirical contributions of the late Jeff Pressing, musician and researcher, several of which were directed toward opening up this area of investigation. It is on the theoretical bases of models such as his that experimentally accessible hypotheses about improvisation can be constructed. The chapter particularly addresses the issue of transitions and segmentation in improvisation. Comparative and cross-cultural studies of the cognition of improvisation are then briefly reviewed. Finally, the potential of cognitive studies not only to elucidate improvisational processes, but also to contribute to them, is described.
Improvising Yoga
Authors: Foster Susan Leigh
Published: June 2014

This chapter explores improvisation during the practice of yoga as a way to consider Foucault’s concept of “techniques of the self.” It describes and analyzes the way that the thinking body and the thinking mind can improvise together to construct a corporeality that resists the docilization of the body that is exerted through advertising, fitness, and health regimens. It thereby contributes to the investigation of improvisation and the politics of the quotidian.
Michel de Montaigne, or Philosophy as Improvisation
Authors: Hampton Timothy
Published: June 2014

This chapter underscores the unique position of Montaigne’sEssaysin the western philosophical tradition. Montaigne’s practice of constantly adding to his previously published essays as his mood and interests changed means that theEssaysare an extended exercise in improvisation. Montaigne’s improvised, provisional philosophical approach has broad implications. Politically, it is intimately linked to his undogmatic rejection of the extremism of the French wars of religion. Intellectually, it underpins his relationship to the classical culture that he inherited from Renaissance humanism. And it binds the philosophical enterprise to the mutability and fragility of the body in ways that are strikingly modern.
Fixing Improvisation
Authors: Kraut Anthea
Published: June 2014

This chapter juxtaposes brief case studies of African American vernacular dancers from the first half of the twentieth century in order to reexamine the relationship between the ideology of intellectual property law and the traditions of jazz and tap dance, which rely heavily on improvisation. The examples of the blackface performer Johnny Hudgins, who claimed a copyright in his pantomime routine in the 1920s, and of Fred and Sledge, the class-act dance duo featured in the hit 1948 musical Kiss Me, Kate, whose choreography was copyrighted by the white modern dancer Hanya Holm, prompt a rethinking of the assumed opposition between the originality and fixity requirements of copyright law and the improvisatory ethos of jazz and tap dance. Ultimately, the chapter argues that whether claiming or disavowing uniqueness, embracing or resisting documentation, African American vernacular dancers were both advantaged and hampered by copyright law.
The Improvisative
Authors: McMullen Tracy
Published: June 2014

This chapter explores the ramifications of musical improvisation for understanding self and other. It argues that contemporary cultural theory is over-invested in Hegelian notions of the self as created through the field of the other and the concomitant emphasis on “recognition” as the central factor in the construction of the subject. This emphasis on recognition is, in part, installed through the theory of performativity. The article illuminates problems with this theory and then offers an alternative theory, the “improvisative,” that focuses on “generosity” rather than “recognition.” It argues that the practice of the improvisative may offer a better approach to effecting human agency than the performative. An examination of the improvisative practices of middle and high school age girls at the Girls’ Jazz and Blues Camp in Berkeley, California demonstrates this effectiveness.
Jurisgenerative grammar (for alto)
Authors: Moten Fred
Published: June 2014

“Jurisgenerative Grammar” is concerned with the interplay of legality and criminality in the generation of language and music. It examines how a kind of fugitive poetics is enacted in the fall into what Martin Heidegger refers to as thecommercium, a social space marked by the propensity for song, chatter, and idle talk. This essay argues that thecommerciumis, in fact, a place for thought and thoughtful creation. Its aesthetic sociality animates the compositional and improvisational practices in which Anthony Braxton is engaged in the making of his “language musics,” even when such music is given in solo performance.
Sondheim’s Genius
Authors: Banfield Stephen
Published: June 2014

This chapter explores the balance and contradictions between Stephen Sondheim’s auteur status and the collaborative world of popular musical theater within which he has worked. Focusing onSweeney Todd, it argues that his liberal arts education has facilitated both intertextual collaboration with past authors and literary traditions (Dickens’s London, the filmHangover Square, and previousSweeney Toddauthors, including George Dibdin Pitt and possibly Austin Rosser) and the exercise of artistic control that is potentially demonic, like Todd’s monstrosity, but held in check by a “vaudeville” aesthetic. The number “God, that’s good!” is analyzed in detail to demonstrate the point.
Sondheim and Postmodernism
Authors: McLaughlin Robert L.
Published: June 2014

This chapter places the musical theater of Stephen Sondheim and his collaborators in two contexts: the late-1960s aesthetic exhaustion of the integrated musical play and the rise of postmodernism as a cultural dominant. Self-referentially unintegrated and self-consciously performative, Sondheim’s musicals move beyond the constraints of the musical play and participate in the postmodern critique of narrative as an aesthetic, epistemological, and ontological structure.Company(1970) andFollies(1971) use a formal critique of narrative to disconnect identity from the structure of the life story.Merrily We Roll Along(1981) employs a backward-moving narrative to problematize a structure-completing, progressive conception of time.Road Show(2008) replaces the exhausted master narrative of the American Dream with multiple temporary and contingent narratives.