bluuebunny/crossref_metadata_2025 huggingface dataset:
A Trp199Glu MauG variant reveals a role for Trp199 interactions with pre‐methylamine dehydrogenase during tryptophan tryptophylquinone biosynthesis
Authors: Abu Tarboush Nafez , Jensen Lyndal M.R. , Wilmot Carrie M. , Davidson Victor L.
Published: May 2013

MauG catalyzes posttranslational modifications of a methylamine dehydrogenase precursor (preMADH) to complete the biosynthesis of its protein‐derived tryptophan tryptophylquinone (TTQ) cofactor. Trp199 is present at the site of interaction between MauG and preMADH and is critical to this process as it mediates hole hopping during the inter‐protein electron transfer that is required for catalysis. Trp199 was converted to Glu and the structure and reactivity of the W199E/preMADH complex were characterized. The results reveal that the nature of residue 199 is also important for productive complex formation between preMADH and MauG.
Perinatal undernutrition stimulates seeking food reward
Authors: da Silva Amanda Alves Marcelino , Borba Tássia Karin Ferreira , de Almeida Lira Lívia , Cavalcante Taisy Cinthia Ferro , de Freitas Manuela Figueiroa Lyra , Leandro Carol Gois , do Nascimento Elizabeth , de Souza Sandra Lopes
Published: May 2013

Experiments in animals have revealed that perinatal nutritional restriction, which manifests in adulthood, increases food intake and preference for palatable foods. Considering this, we aimed to evaluate the effects of perinatal malnutrition on hedonic control of feeding behavior. In this study, we divided Wistar rats into two groups according to the diet provided to their mothers during pregnancy and lactation: the control group (diet with 17% casein) and low‐protein group (diet with 8% casein). We assessed the animals’ motivational behavior in adulthood by giving them a stimulus of food reward. We also assessed their neuronal activation triggered by the stimulus of palatable food using FOS protein labeling of neurons activated in the caudate putamen, paraventricular, dorsomedial, ventromedial, and lateral hypothalamic nuclei and amygdala. Evaluation of body weight in malnourished animals showed reduction from the 6th day of life until adulthood. Analysis of feeding behavior revealed that these animals were more motivated by food reward, but they had delays during learning of the task. This finding correlated with the number of c‐FOS‐immunoreactive neurons, which indicated that malnourished animals had an increase in the number of neurons activated in response to the palatable diet, especially in the amygdala and caudate putamen. The study therefore confirmed our hypothesis that early nutritional insults promote changes in encephalic control mechanisms, especially those related to food intake and search for reward.
God, the devil, and the details: Fleshing out the predictive processing framework
Authors: Rasmussen Daniel , Eliasmith Chris
Published: May 2013

The predictive processing framework lacks many of the architectural and implementational details needed to fully investigate or evaluate the ideas it presents. One way to begin to fill in these details is by turning to standard control-theoretic descriptions of these types of systems (e.g., Kalman filters), and by building complex, unified computational models in biologically realistic neural simulations.

God is in the details

— Mies van der Rohe

The devil is in the details

— Anonymous
Distinguishing theory from implementation in predictive coding accounts of brain function
Authors: Spratling Michael W.
Published: May 2013

It is often helpful to distinguish between a theory (Marr's computational level) and a specific implementation of that theory (Marr's physical level). However, in the target article, a single implementation of predictive coding is presented as if this were the theory of predictive coding itself. Other implementations of predictive coding have been formulated which can explain additional neurobiological phenomena.
Schizophrenia-related phenomena that challenge prediction error as the basis of cognitive functioning
Authors: Silverstein Steven M.
Published: May 2013

There are aspects of schizophrenia that pose challenges for Clark's model. These include: (1) evidence for excitatory activity underlying self-organizing neural ensembles that support coordinating functions, and their impairment in schizophrenia; (2) evidence regarding hallucinations that suggest they are not due to excessive prediction error; and (3) the critical role of emotional factors as setting conditions for delusion formation.
Applications of predictive control in neuroscience
Authors: Bridgeman Bruce
Published: May 2013

The sensory cortex has been interpreted as coding information rather than stimulus properties since Sokolov in 1960 showed increased response to an unexpected stimulus decrement. The motor cortex is also organized around expectation, coding the goal of an act rather than a set of muscle movements. Expectation drives not only immediate responses but also the very structure of the cortex, as demonstrated by development of receptive fields that mirror the structure of the visual world.
Predictions in the light of your own action repertoire as a general computational principle
Authors: König Peter , Wilming Niklas , Kaspar Kai , Nagel Saskia K. , Onat Selim
Published: May 2013

We argue that brains generate predictions only within the constraints of the action repertoire. This makes the computational complexity tractable and fosters a step-by-step parallel development of sensory and motor systems. Hence, it is more of a benefit than a literal constraint and may serve as a universal normative principle to understand sensorimotor coupling and interactions with the world.
Whenever next: Hierarchical timing of perception and action
Authors: Holm Linus , Madison Guy
Published: May 2013

The target article focuses on the predictive coding of “what” and “where” something happened and the “where” and “what” response to make. We extend that scope by addressing the “when” aspect of perception and action. Successful interaction with the environment requires predictions of everything from millisecond-accurate motor timing to far future events. The hierarchical framework seems appropriate for timing.
The brain is not an isolated “black box,” nor is its goal to become one
Authors: Froese Tom , Ikegami Takashi
Published: May 2013

In important ways, Clark's “hierarchical prediction machine” (HPM) approach parallels the research agenda we have been pursuing. Nevertheless, we remain unconvinced that the HPM offers the best clue yet to the shape of a unified science of mind and action. The apparent convergence of research interests is offset by a profound divergence of theoretical starting points and ideal goals.
Backwards is the way forward: Feedback in the cortical hierarchy predicts the expected future
Authors: Muckli Lars , Petro Lucy S. , Smith Fraser W.
Published: May 2013

Clark offers a powerful description of the brain as a prediction machine, which offers progress on two distinct levels. First, on an abstract conceptual level, it provides a unifying framework for perception, action, and cognition (including subdivisions such as attention, expectation, and imagination). Second, hierarchical prediction offers progress on a concrete descriptive level for testing and constraining conceptual elements and mechanisms of predictive coding models (estimation of predictions, prediction errors, and internal models).
Affect and non-uniform characteristics of predictive processing in musical behaviour
Authors: Schaefer Rebecca S. , Overy Katie , Nelson Peter
Published: May 2013

The important roles of prediction and prior experience are well established in music research and fit well with Clark's concept of unified perception, cognition, and action arising from hierarchical, bidirectional predictive processing. However, in order to fully account for human musical intelligence, Clark needs to further consider the powerful and variable role of affect in relation to prediction error.
What else can brains do?
Authors: Sloman Aaron
Published: May 2013

The approach Clark labels “action-oriented predictive processing” treats all cognition as part of a system of on-line control. This ignores other important aspects of animal, human, and robot intelligence. He contrasts it with an alleged “mainstream” approach that also ignores the depth and variety of AI/Robotic research. I don't think the theory presented is worth taking seriously as a complete model, even if there is much that it explains.
Maternal and perinatal factors associated with subsequent meningococcal, Haemophilus or enteroviral meningitis in children: database study
Authors: GOLDACRE M. J. , WOTTON C. J. , MAISONNEUVE J. J.
Published: May 2013

We used a database of 248 659 births, with follow-up to subsequent disease, in the Oxford record linkage archive (1979–1999) to study the influence of family, maternal, and perinatal factors on subsequent hospital admission for meningococcal, Haemophilus, and enteroviral meningitis in the children. In this summary, we report key findings that were significant in multivariate analysis. Meningococcal meningitis was significantly associated with maternal smoking [odds ratio (OR) 2·1, 95% confidence interval (CI) 1·2–3·7]. Haemophilus meningitis was associated with having older siblings (e.g. second child compared to first-born, OR 3·3, 95% CI 2·0–5·6). Enteroviral meningitis was associated with low birth weight (OR 2·2, 95% CI 1·3–3·6) and male sex (OR 1·7, 95% CI 1·2–2·3). The mothers of six of the 312 children with enteroviral meningitis had previously had enteroviral meningitis themselves. We concluded that several maternal characteristics influence the risk of these types of meningitis.
Diarrhoea-related knowledge and practice of physicians in urban slums of Kolkata, India
Authors: KANUNGO S. , MAHAPATRA T. , BHADURI B. , MAHAPATRA S. , CHAKRABORTY N. D. , MANNA B. , SUR D.
Published: May 2013

Diarrhoeal management practices are unsatisfactory in India especially in the slum areas. Dearth of information regarding physicians' diarrhoea-related knowledge and practice in India ncessitated this cross-sectional study of allopathic practitioners in the slums of Kolkata, to assess the distribution and interrelationship between physicians' characteristics, knowledge and practice regarding diarrhoea. A total of 264 randomly selected consenting practitioners were interviewed using a field-tested questionnaire. Nineteen percent had good overall knowledge, 49% and 80% prescribed antibiotics to diarrhoea and cholera patients, respectively, and 55% advised stool examination for every case. Qualified and Government physicians had better knowledge regarding diarrhoea [MBBS: odds ratio (OR) 5·96,P < 0·001; postgraduates: OR 9·33,P < 0·001; Government physicians: OR 11·49,P < 0·0001] and were less likely to prescribe antibiotics for all diarrhoea cases (MBBS: OR 0·30,P = 0·002; postgraduates: OR 0·20,P < 0·001; Government physicians OR 0·24,P < 0·029). Better knowledge was associated with a lower likelihood of prescribing antibiotics for diarrhoea (OR 0·72,P < 0·001), cholera (OR 0·78,P = 0·027) and investigative procedure (OR 0·85,P = 0·028). In the slums of Kolkata, diarrhoea-related knowledge and practice were poor with the exception of qualified physicians, hence an improvement in the knowledge of pharmacists and unqualified practitioners is necessary for the overall improvement of diarrhoeal management in these slums.
INTRODUCTION AND COMMENTARY FOR F. A. HAYEK’S “THE OVERRATED REASON”
Authors: GICK EVELYN , RUNST PETRIK
Published: May 2013

The translation titled “The Overrated Reason” is based on the German text “Die Überschätzte Vernunft,” by Friedrich Hayek—a lecture that Hayek gave at a symposium at Castle Kleβheim in early 1982.
A Normal Accident or a Sea-Change? Nuclear Host Communities Respond to the 3/11 Disaster
Authors: ALDRICH DANIEL P.
Published: May 2013

While 3/11 has altered energy policies around the world, insufficient attention has focused on reactions from local nuclear power plant host communities and their neighbors throughout Japan. Using site visits to such towns, interviews with relevant actors, and secondary and tertiary literature, this article investigates the community crisis management strategies of two types of cities, towns, and villages: those which have nuclear plants directly in their backyards and neighboring cities further away (within a 30 mile radius). Responses to the disaster have varied with distance to nuclear facilities but in a way contrary to the standard theories based on the concept of the ‘distance decay function’. Officials in communities directly proximal to nuclear power plants by and large remain supportive of Japan's nuclear power program, while those in cities and towns at a distance (along with much of the general public) have displayed strong opposition to the pre 3/11 status quo. Using qualitative data, this article underscores how national energy and crisis response policies rest strongly on the political economy, experiences of, and decisions made at the subnational level.
A national approach to improving adolescent and young adult (AYA) oncology psychosocial care: The development of AYA-specific psychosocial assessment and care tools
Authors: Palmer Susan , Patterson Pandora , Thompson Kate
Published: May 2013

Objective:

Age-based screening tools and assessment measures are crucial to the provision of best practice care for adolescent and young adult (AYA) cancer patients. Unfortunately, there are limited psychosocial tools developed for this age group and pediatric or adult measures are often distributed with the assumption that they are “close enough.” We describe a collaborative Australian project that strives to improve what currently exists for the psychosocial assessment of and planning for the 15–25-year-old age group.

Method:

Using the National Comprehensive Cancer Network's Distress Thermometer and the HEADSS Assessment as a foundation, the tools were developed in consultation with Australia's leading AYA clinicians, AYAs currently undergoing medical treatment, and a group of AYA survivors through a process of discussion groups and clinical interviews.

Results:

The result is the first available AYA-specific screening tool, care plan pro forma, and psychosocial assessment measure developed for use within the oncology sector. These new tools will assist clinicians working with this population group to support psychosocial coping during active treatment and promote healthy post-treatment survivorship.

Significance of results:

Over time, further validation procedures will add to the veracity of the measures. Until then, these measures represent the best available in Australia. They highlight a clinically recognized minimum standard of care that all young cancer patients, regardless of treatment location, have the right to receive.
Enhanced microRNA accumulation through stemloop‐adjacent introns
Authors: Schwab Rebecca , Speth Corinna , Laubinger Sascha , Voinnet Olivier
Published: May 2013

MicroRNAs (miRNAs) originate from stemloop‐forming precursor RNAs found in longer primary transcripts that often contain introns. We show that in plants, those introns, when located 3′ of the stemloop, can promote mature miRNA accumulation, through a mechanism that likely operates at the level of miRNA processing or stability. Reversely, when miRNA production is reduced such as in dicer‐like 1 mutants, splicing of introns that promote miRNA processing is considerably increased, pointing to a tight physical and temporal coordination of intron splicing and miRNA processing in plants. Our findings further suggest that miRNA transcripts without introns generated through alternative polyA‐site usage might contribute to the differential adjustment of miRNA levels, possibly at a tissue‐specific level.
Identification of a potent salicylic acid-based inhibitor of tyrosine phosphatase PTP1B
Authors: Haftchenary Sina , Ball Daniel P. , Aubry Isabelle , Landry Melissa , Shahani Vijay M. , Fletcher Steven , Page Brent D. G. , Jouk Andriana O. , Tremblay Michel L. , Gunning Patrick T.
Published: May 2013

A screen of a library of diverse small-molecules against a subset of phosphatases identified 7b and 7c, which potently inhibit TC-PTP, PTPσ and PTP1B with no inhibition of PTP-LAR, PRL2 A/S, MKPX or papain.
Orphan spin operators enable the acquisition of multiple 2D and 3D magic angle spinning solid-state NMR spectra
Authors: Gopinath T. , Veglia Gianluigi
Published: May 2013

We propose a general method that enables the acquisition of multiple 2D and 3D solid-state NMR spectra for U-13C, 15N-labeled proteins. This method, called MEIOSIS (Multiple ExperIments via Orphan SpIn operatorS), makes it possible to detect four coherence transfer pathways simultaneously, utilizing orphan (i.e., neglected) spin operators of nuclear spin polarization generated during 15N-13C cross polarization (CP). In the MEIOSIS experiments, two phase-encoded free-induction decays are decoded into independent nuclear polarization pathways using Hadamard transformations. As a proof of principle, we show the acquisition of multiple 2D and 3D spectra of U-13C, 15N-labeled microcrystalline ubiquitin. Hadamard decoding of CP coherences into multiple independent spin operators is a new concept in solid-state NMR and is extendable to many other multidimensional experiments. The MEIOSIS method will increase the throughput of solid-state NMR techniques for microcrystalline proteins, membrane proteins, and protein fibrils.
Photoinduced electron transfer at a Si(111) nanostructured surface:
Effect of varying light wavelength, temperature, and structural
parameters
Authors: Noether Celeste O. , Micha David A.
Published: May 2013

We treat electronic dynamics at surfaces of nanostructured semiconductors induced by absorption of visible light using reduced density matrices and properties obtained from ab initio electronic structure calculations, to focus on two non-adiabatic phenomena: (a) how active electrons interacting non-adiabatically with atoms at the surface undergo electronic transitions and (b) how active electrons interacting by exchanging energy with excitons in the medium undergo a dissipative non-adiabatic dynamics. We test the effects on charge separation from varying oscillator strengths, non-adiabatic momentum couplings, the rates of relaxation of excited states coupled to the medium, temperature, and light wavelength. Varying the oscillator strength displays the interplay between competing relaxation and charge transfer dynamics. Varying the non-adiabatic momentum coupling between excited and final states demonstrates the importance of including enough vibrational levels to model the full dynamics of the system and further shows the interplay of relaxation and charge transfer from the final state to the excited state. Larger electron transfer probabilities and longer lasting charge separation occur when oscillator strength into the intermediate state decreases, or when it increases into the final state, and when temperature increases. Longer lasting charge separation also occurs when the non-adiabatic momentum coupling decreases, a somewhat unexpected result which is due to the combined effect of population relaxation and transitions among many vibronic states.
Electron ionisation of sulfur dioxide
Authors: Fletcher James D. , Parkes Michael A. , Price Stephen D.
Published: May 2013

Relative precursor-specific partial ionisation cross sections for the fragment ions formed following electron ionisation of sulfur dioxide (SO2) have been measured for the first time, from 30 to 200 eV, using time-of-flight mass spectrometry coupled with two-dimensional ion coincidence detection. These data quantify the yields of O2+, O+, SO2+, S+, O2+, and SO+ ions, relative to the formation of SO2+, via single, double, and triple electron ionisation of SO2. Formation of O2+, following electron-SO2 collisions, has been quantified for the first time. The data allow a first experimental estimate of the triple ionisation potential of SO2 (69.0 ± 3.6 eV), an energy in good agreement with a value derived in this study via computational chemistry. The triple ion combination S+ + O+ + O+ is clearly detected following electron collisions with SO2 at electron energies markedly below the vertical energy for forming SO23 +. This observation is accounted for by the operation of a stepwise pathway to the formation of S+ + 2O+ which does not involve the formation of a molecular trication.
Approximately clean quantum probability measures
Authors: Farenick Douglas , Floricel Remus , Plosker Sarah
Published: May 2013

A quantum probability measure–or quantum measurement–is said to be clean if it cannot be irreversibly connected to any other quantum probability measure via a quantum channel. The notion of a clean quantum measure was introduced by Buscemi et al. [“Clean positive operator valued measures,” J. Math. Phys. 46(8), 082109 (2005)10.1063/1.2008996] for finite-dimensional Hilbert space, and was studied subsequently by Kahn [“Clean positive operator-valued measures for qubits and similar cases,” J. Phys. A 40(18), 4817–4832 (2007)10.1088/1751-8113/40/18/009] and Pellonpää [“Complete characterization of extreme quantum observables in finite dimensions,” J. Phys. A 44(8), 085304 (2011)10.1088/1751-8113/44/8/085304]. The present paper provides new descriptions of clean quantum probability measures in the case of finite-dimensional Hilbert space. For Hilbert spaces of infinite dimension, we introduce the notion of “approximately clean quantum probability measures” and characterise this property for measures whose range determines a finite-dimensional operator system.
Phonon-assisted Zener tunneling in a cylindrical nanowire transistor
Authors: Carrillo-Nuñez H. , Magnus Wim , Vandenberghe William G. , Sorée Bart , Peeters François M.
Published: May 2013

The tunneling current has been computed for a cylindrical nanowire tunneling field-effect transistor (TFET) with an all-round gate that covers the source region. Being the underlying mechanism, band-to-band tunneling, mediated by electron–phonon interaction, is pronouncedly affected by carrier confinement in the radial direction and, therefore, involves the self-consistent solution of the Schrödinger and Poisson equations. The latter has been accomplished by exploiting a non-linear variational principle within the framework of the modified local density approximation taking into account the nonparabolicity of both the valence band and conduction band in relatively thick wires. Moreover, while the effective-mass approximation might still provide a reasonable description of the conduction band in relatively thick wires, we have found that the nonparabolicity of the valence band needs to be included. As a major conclusion, it is observed that confinement effects in nanowire tunneling field-effect transistors have a stronger impact on the onset voltage of the tunneling current in comparison with planar TFETs. On the other hand, the value of the onset voltage is found to be overestimated when the valence band nonparabolicity is ignored.
The conduction mechanism of large on/off ferroelectric diode currents in epitaxial (111) BiFeO3 thin film
Authors: Chen Zhihui , He Long , Zhang Fan , Jiang Jun , Meng Jianwei , Zhao Boyuan , Jiang Anquan
Published: May 2013

The large ferroelectric diode current modulated by bipolar polarization in epitaxial (111) BiFeO3 thin film has been observed. With the survey of different current leakage models, it is found that the space-charge limited current dominates the conduction. For the intrinsic physical understanding, the rectification of diode currents near domain coercive fields is attributed to gradient distribution of the trap charges between top and bottom electrode/ferroelectric interfaces, and the distributed charges can be reversed upon polarization reversal. Moreover, the retention time of the On and Off diode currents is over 104 s with their ratio of around 5:1.
Ferromagnetic resonance of transversally magnetized amorphous microwires and nanowires
Authors: Kraus Luděk , Frait Zdeněk , Ababei Gabriel , Chiriac Horia
Published: May 2013

Ferromagnetic resonance of very thin glass covered wires with diameters ranging from 25 μm down to 133 nm was investigated at microwave frequencies 49.1 and 69.7 GHz at room temperature. The static magnetic field was applied perpendicular to the wire axis. The resonance spectra substantially change when the wire diameter decreases below the electromagnetic skin depth. Depending on the wire thickness and the experimental arrangement, various resonance modes can be excited. In thick wires, an inhomogeneously broadened resonance curve, with two distinct peaks at minimum and maximum resonance fields, can be seen. In submicron wires, generally three narrow resonances can be observed. The weak central resonance peak corresponds to the uniform precession (Kittel) resonance mode and is excited by the uniform component of microwave magnetic field. The other two belong to non-uniform magnetostatic modes, which are excited by the strong circumferential magnetic field due to electric polarization of the wire. The experimental results are explained using a strong skin effect limit and a quasistatic approximation for the bulk and submicron wires, respectively.
Prediction of probabilistic ignition behavior of polymer-bonded explosives from microstructural stochasticity
Authors: Barua A. , Kim S. , Horie Y. , Zhou M.
Published: May 2013

Random variations in constituent properties, constituent distribution, microstructural morphology, and loading cause the ignition of explosives to be inherently stochastic. An approach is developed to computationally predict and quantify the stochasticity of the ignition process in polymer-bonded explosives (PBXs) under impact loading. The method, the computational equivalent of carrying out multiple experiments under the same conditions, involves subjecting sets of statistically similar microstructure samples to identical overall loading and characterizing the statistical distribution of the ignition response of the samples. Specific quantities predicted based on basic material properties and microstructure attributes include the critical time to ignition at given load intensity and the critical impact velocity below which no ignition occurs. The analyses carried out focus on the influence of random microstructure geometry variations on the critical time to ignition at given load intensity and the critical impact velocity below which no ignition occurs. Results show that the probability distribution of the time to criticality (tc) follows the Weibull distribution. This probability distribution is quantified as a function of microstructural attributes including grain volume fraction, grain size, specific binder-grain interface area, and the stochastic variations of these attributes. The relations reveal that the specific binder-grain interface area and its stochastic variation have the most influence on the critical time to ignition and the critical impact velocity below which no ignition is observed. For a PBX with 95% octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine content, the computationally predicted minimum impact velocity for ignition is in the range of 54–63 ms−1 depending on microstructure. This range is comparable to values measured experimentally for PBX9501 (53 ms−1 by Chidester et al., “Low amplitude impact testing and analysis of pristine and aged solid high explosives,” in Eleventh (International) Symposium on Detonation, ONR (1998), 33300. 60–84 ms−1 by Gruau et al., “Ignition of a confined high explosive under low velocity impact,” Int. J. Impact Eng. 36, 537–550 (2009)).
Quantification of atomic intermixing in short-period InAs/GaSb superlattices for infrared photodetectors
Authors: Ashuach Y. , Kauffmann Y. , Saguy C. , Grossman S. , Klin O. , Weiss E. , Zolotoyabko E.
Published: May 2013

Cross-sectional scanning tunneling microscopy (XSTM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) are applied for characterizing the MBE-grown short-period InAs/GaSb superlattices for mid- and long-wavelength infrared detection. The focus of this study is on atomic intermixing in close proximity to the interfaces, which is a key issue for device performance. HAADF-STEM permits visualization of the anion-cation dumbbells in individual sub-layers and is even capable to resolve anions and cations separated by 0.15 nm within a dumbbell. On this basis, the interfacial width is extracted with high accuracy. XSTM technique allows us direct counting of certain kinds of atoms within atomic rows, which sheds light on compositional fluctuations and isovalent atomic intermixing. Both methods reveal rather abrupt interfaces with InAs-on-GaSb interfaces being slightly wider than GaSb-on-InAs interfaces. According to HAADF-STEM, in the set of investigated samples, the 90%-to-10% interface width is confined within 2.6–4.4 monolayers (0.8–1.3 nm). In all the samples studied, XSTM analysis showed some residual concentration (on the level of a few atomic percent) of Sb atoms in the middle of the InAs sub-layers, as a result of As/Sb substitutions during growth. The level of intermixing is diminishing with increasing the thickness of individual InAs layers.
Precision electromagnetic calibration technique for micro-Newton thrust stands
Authors: He Zhen , Wu Jianjun , Zhang Daixian , Lu Gaofei , Liu Zejun , Zhang Rui
Published: May 2013

This paper introduces a new direct non-contact electromagnetic calibration technique for high precision measurements of micro-thrust and impulse. A ring-shaped electromagnet with an air gap is used in the calibration. The calibration force is produced by the interaction of a uniform magnetic field with a copper wire current in the air gap. This force depends linearly on this current as well as the steady angular displacement of the torsion arm of the thrust stand. The range of calibration force is very large and the calibration force is easy to generate and insensitive to the arm displacement. The calibration uncertainty for a 150-μN force is 4.17 μN. The more influential factor on the calibration uncertainty is the magnetization of the electromagnet core due to the copper wire current. In the impulse calibration, the exerted impulse is linearly dependent on the maximal angular displacement of the torsion arm. The uncertainty in the impulse calibration is determined by uncertainties in both the force calibration and the pulse time.
Asymmetric Lamb wave propagation in phononic crystal slabs with graded grating
Authors: Chen Jiu-jiu , Han Xu , Li Guang-Yao
Published: May 2013

Asymmetric Lamb wave propagation is important for control and manipulation of the Lamb wave signals in various devices. Through numerical simulation of the Lamb wave propagation in phononic crystal slabs with graded grating, we proposed and studied a linear phononic device that shows asymmetric Lamb wave transmission in low-frequency domains. This exotic phenomenon stems from the threshold frequency of the fundamental antisymmetric Lamb mode conversion to the fundamental symmetric Lamb mode is different at the different locations of the acoustic diode. Remarkably, a bi-directional asymmetric Lamb wave propagation is achieved by tuning the grade of the grating depths. The back propagating acoustic waves of the second band of hybridized Lamb modes plays the essential role in the phenomena for relatively high-frequency regions. This should be potentially significant in helping design chip-scale integrated phononic devices.
Ultraviolet/visible photodiode of nanostructure Sn–doped ZnO/Si heterojunction
Authors: Kheirandish N. , Mortezaali A.
Published: May 2013

Sn doped ZnO nanostructures deposited on Si substrate with (100) orientation by spray pyrolysis method at temperature 450 °C. Sn/Zn atomic ratio varies from 0% to 5%. The scanning electron microscope measurements showed that size of particles reduce with increasing the doping concentration. The X-ray diffraction analysis revealed formation of the wurtzite phase of ZnO. I-V curves of Sn doped ZnO/Si were investigated in dark and shows diode-like rectifying behavior. Among doped ZnO/Si, sample with atomic ratio of Sn/Zn = 5% is a good candidate to study photodiode properties in UV/visible range. Photoelectric effects have been observed under illumination monochromatic laser light with a wavelength of 325 nm and halogen lamp. Measurements demonstrate that the photodiode has high sensitivity and reproducibility to halogen light respect to laser light.
High thermal stability of optical transparency in cellulose nanofiber paper
Authors: Nogi Masaya , Kim Changjae , Sugahara Tohru , Inui Tetsuji , Takahashi Tsukasa , Suganuma Katsuaki
Published: May 2013

Cellulose nanopapers have been shown to maintain high optical transparency after high temperature heating at 150 °C. High temperature heating to around 150 °C is inevitable in electronic device processing. If a polyethylene terephthalate film is held at 150 °C for tens of minutes, cyclic oligomers migrate to the film surface, causing surface roughness that decreases the film transparency. However, because cellulose nanofibers have high thermal stability, the transparent nanopapers maintained their smooth surfaces and high optical transparency, even after heating to 150 °C for tens of minutes. These findings indicate the suitability of cellulose nanofiber papers for continuous roll-to-roll processing.
Low-temperature epitaxial growth of high quality Si1−xGex (x ≥ 0.99) films on Si(001) wafer by reactive thermal chemical vapor deposition
Authors: Tao Ke , Kurosawa Yoshinori , Hanna Jun-ichi
Published: May 2013

Epitaxial growth of silicon-germanium (Si1−xGex: 0 ≤ x ≤ 1) thin films on Si(001) substrate at low temperature has been investigated using reactive thermal CVD. Si2H6 and GeF4 are used as source gases. The results indicate that Si1−xGex (x ≥ 0.99) epilayer can be prepared directly on Si wafer at 350 °C with the degree of strain relaxation up to 98.5%. Etching reaction between GeF4 and the growth surface plays an important role in both improving the crystal quality and suppressing the propagation of dislocations. High quality epitaxial Si1−xGex has been fabricated with a threading dislocation density of ∼7.0 × 105 cm−2 and RMS roughness of 1.44 nm.
Spatially and temporally resolved temperature and shock-speed measurements behind a laser-induced blast wave of energetic nanoparticles
Authors: Roy Sukesh , Jiang Naibo , Stauffer Hans U. , Schmidt Jacob B. , Kulatilaka Waruna D. , Meyer Terrence R. , Bunker Christopher E. , Gord James R.
Published: May 2013

Spatially and temporally resolved temperature measurements behind an expanding blast wave are made using picosecond (ps) N2 coherent anti-Stokes Raman scattering (CARS) following laser flash heating of mixtures containing aluminum nanoparticles embedded in ammonium-nitrate oxidant. Production-front ps-CARS temperatures as high as 3600 ± 180 K—obtained for 50-nm-diameter commercially produced aluminum-nanoparticle samples—are observed. Time-resolved shadowgraph images of the evolving blast waves are also obtained to determine the shock-wave position and corresponding velocity. These results are compared with near-field blast-wave theory to extract relative rates of energy release for various particle diameters and passivating-layer compositions.
Note: Slowing-down of diffusion-controlled reactions in dense liquid matter
Authors: Zaccone A.
Published: May 2013

We show that the slowing-down of diffusion-limited reaction rates in dense liquids can be explained in terms of an effective two-body Smoluchowski framework where many-body correlations are accounted for by means of a nonequilibrium mean-force field. This framework explains recent observations from numerical simulations.
Polarity control and growth of lateral polarity structures in AlN
Authors: Kirste Ronny , Mita Seiji , Hussey Lindsay , Hoffmann Marc P. , Guo Wei , Bryan Isaac , Bryan Zachary , Tweedie James , Xie Jinqiao , Gerhold Michael , Collazo Ramón , Sitar Zlatko
Published: May 2013

The control of the polarity of metalorganic chemical vapor deposition grown AlN on sapphire is demonstrated. Al-polar and N-polar AlN is grown side-by-side yielding a lateral polarity structure. Scanning electron microscopy measurements reveal a smooth surface for the Al-polar and a relatively rough surface for the N-polar AlN domains. Transmission electron microscopy shows mixed edge-screw type dislocations with polarity-dependent dislocation bending. Raman spectroscopy reveals compressively strained Al-polar and relaxed N-polar domains. The near band edge luminescence consists of free and bound excitons which are broadened for the Al-polar AlN. Relaxation, better optical quality, and dislocation bending in the N-polar domains are explained by the columnar growth mode.
Influence of crystalline titanium oxide layer smoothness on the performance of inverted organic bilayer solar cells
Authors: Berner Etienne , Jäger Timo , Lanz Thomas , Nüesch Frank , Tisserant Jean-Nicolas , Wicht Gaetan , Zhang Hui , Hany Roland
Published: May 2013

Due to the small exciton diffusion length in organic materials, the donor-acceptor heterointerface in simple bilayer solar cells must be placed in close proximity to the bottom electrode. This makes great demands on the planarity of the base layer, since a non-uniform topography can cause adverse shorting through overlying layers. We fabricated indium tin oxide (ITO)/titanium oxide (TiOx)/fullerene (C60)/cyanine dye/molybdenum oxide (MoO3)/silver (Ag) solar cells with TiOx layers deposited via sputtering, coated from a nanoparticle suspension or prepared via a sol-gel process. A power conversion efficiency of 3.7% was measured when using a smooth sol-gel derived TiOx film.
Two-electron-satellite transition of donor bound exciton in ZnO: Radiative Auger effect
Authors: Wang X. H. , Xu S. J.
Published: May 2013

Two-electron-satellite (TES) transition of donor bound exciton (D0X) is an interesting many-body quantum process. In this letter, precise luminescence spectra and temperature behaviors of the TES transition of aluminum bound exciton in two kinds of zinc oxide single crystals were investigated in detail. It is found that the TES transition can be treated as a radiative Auger process in which the temperature dependence of the emission intensity of the transition can be fitted very well with a model taking into account the temperature dependent Auger term and thermal dissociation of the D0X excitons.
A face-shear mode single crystal ultrasonic motor
Authors: Li Shiyang , Jiang Wenhua , Zheng Limei , Cao Wenwu
Published: May 2013

We report a face-shear mode ultrasonic motor (USM) made of [011]c poled Zt ± 45° cut 0.24Pb(In1/2Nb1/2)O3-0.46Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 single crystal, which takes advantage of the extremely large d36 = 2368 pC/N. This motor has a maximum no-load linear velocity of 182.5 mm/s and a maximum output force of 1.03 N under the drive of Vp = 50 V, f = 72 kHz. Compared with the k31 mode USM made of Pb(Zr,Ti)O3 (PZT), our USM has simpler structure, lower driving frequency, much higher electromechanical coupling factor, and twice power density. This USM can be used for low frequency operation as well as cryogenic actuation with a large torque.
Effects of collisions on energetic particle-driven chirping bursts
Authors: Lesur M.
Published: May 2013

In the presence of an energetic particle population in a dissipative plasma, self-trapped structures in phase-space (holes and clumps) emerge from nonlinear wave-particle interactions. Their dynamics can lead to a nonlinear continuous shifting of the wave frequency (chirping). The effects of collisions on chirping characteristics are investigated, with a one-dimensional kinetic model. Existing analytic theory is extended to account for Krook-like collisions, which quantitatively explains a significant departure from widely accepted square-root time dependency. Relaxation oscillations, associated with chirping bursts, are investigated in the presence of dynamical friction and velocity-diffusion. The period increases with decreasing drag and weakly increases with decreasing diffusion. The mechanism is clarified with a simple semi-analytic model of hole/clump pair, which satisfies a Fokker-Planck equation. The model shows that the linear growth rate cannot be obtained simply by fitting an exponential to the amplitude time-series.
AgInSbTe memristor with gradual resistance tuning
Authors: Zhang J. J. , Sun H. J. , Li Y. , Wang Q. , Xu X. H. , Miao X. S.
Published: May 2013

A chalcogenide material with Ag/Ag5In5Sb60Te30/Ag structure was proposed as a memristor. Reproducible gradual resistance tuning in bipolar/unipolar modes was demonstrated. The resistance variation was tuned more precisely by controlling the polarity, the amplitude, the width, and the number of applied voltage pulses. The bipolar memristive switch was attributed to the coexistence of intrinsic space charge limited conduction and extrinsic electrochemical metallization effect. Moreover, the unipolar gradual resistance tuning reconfirmed the electrochemical metallization effect. The gradual resistance tuning characteristics will promote this memristor to potential application in mimicking biological plastic synapses.
Vaccine-induced plasma IgA specific for the C1 region of the HIV-1 envelope blocks binding and effector function of IgG
Authors: Tomaras Georgia D. , Ferrari Guido , Shen Xiaoying , Alam S. Munir , Liao Hua-Xin , Pollara Justin , Bonsignori Mattia , Moody M. Anthony , Fong Youyi , Chen Xi , Poling Brigid , Nicholson Cindo O. , Zhang Ruijun , Lu Xiaozhi , Parks Robert , Kaewkungwal Jaranit , Nitayaphan Sorachai , Pitisuttithum Punnee , Rerks-Ngarm Supachai , Gilbert Peter B. , Kim Jerome H. , Michael Nelson L. , Montefiori David C. , Haynes Barton F.
Published: May 2013

Analysis of correlates of risk of infection in the RV144 HIV-1 vaccine efficacy trial demonstrated that plasma IgG against the HIV-1 envelope (Env) variable region 1 and 2 inversely correlated with risk, whereas HIV-1 Env-specific plasma IgA responses directly correlated with risk. In the secondary analysis, antibody-dependent cellular cytotoxicity (ADCC) was another inverse correlate of risk, but only in the presence of low plasma IgA Env-specific antibodies. Thus, we investigated the hypothesis that IgA could attenuate the protective effect of IgG responses through competition for the same Env binding sites. We report that Env-specific plasma IgA/IgG ratios are higher in infected than in uninfected vaccine recipients in RV144. Moreover, Env-specific IgA antibodies from RV144 vaccinees blocked the binding of ADCC-mediating mAb to HIV-1 Env glycoprotein 120 (gp120). An Env-specific monomeric IgA mAb isolated from an RV144 vaccinee also inhibited the ability of natural killer cells to kill HIV-1–infected CD4+T cells coated with RV144-induced IgG antibodies. We show that monomeric Env-specific IgA, as part of postvaccination polyclonal antibody response, may modulate vaccine-induced immunity by diminishing ADCC effector function.
Robust measurement of telomere length in single cells
Authors: Wang Fang , Pan Xinghua , Kalmbach Keri , Seth-Smith Michelle L. , Ye Xiaoying , Antumes Danielle M. F. , Yin Yu , Liu Lin , Keefe David L. , Weissman Sherman M.
Published: May 2013

Significance

Telomeres are the structures at the ends of chromosomes that protect these ends from degradation or joining to one another. Telomeres consist of repeat DNA sequences and the length is gradually eroded as the cell ages. The ability to measure telomere length in individual cells would be important for studies of cell senescence, malignancy, stem cell renewal, and human fertility. We have developed a robust and practical method for estimating the telomere length of single cells, and used this method to demonstrate the heterogeneity or changes of telomere length in several systems.
A family of number fields with unit rank at least 4 that has Euclidean ideals
Authors: Graves Hester , Murty M.
Published: May 2013

We will prove that if the unit rank of a number field with cyclic class group is large enough and if the Galois group of its Hilbert class field over

Q

\mathbb {Q}

is abelian, then every generator of its class group is a Euclidean ideal class. We use this to prove the existence of a non-principal Euclidean ideal class that is not norm-Euclidean by showing that

Q

(

5

,

21

,

22

)

\mathbb {Q}(\sqrt {5}, \sqrt {21}, \sqrt {22})

has such an ideal class.
pyDockWEB: a web server for rigid-body protein–protein docking using electrostatics and desolvation scoring
Authors: Jiménez-García Brian , Pons Carles , Fernández-Recio Juan
Published: May 2013

Summary: pyDockWEB is a web server for the rigid-body docking prediction of protein–protein complex structures using a new version of the pyDock scoring algorithm. We use here a new custom parallel FTDock implementation, with adjusted grid size for optimal FFT calculations, and a new version of pyDock, which dramatically speeds up calculations while keeping the same predictive accuracy. Given the 3D coordinates of two interacting proteins, pyDockWEB returns the best docking orientations as scored mainly by electrostatics and desolvation energy.

Availability and implementation: The server does not require registration by the user and is freely accessible for academics at http://life.bsc.es/servlet/pydock

Contact:  juanf@bsc.es

Supplementary information:  Supplementary data are available at Bioinformatics online.
Patient-Satisfaction Measures in Anesthesia
Authors: Barnett Sarah F. , Alagar Ravi K. , Grocott Michael P. W. , Giannaris Savvas , Dick John R. , Moonesinghe Suneetha Ramani
Published: May 2013

Patient satisfaction is an important measure of the quality of health care and is used as an outcome measure in interventional and quality improvement studies. Previous studies have found that there are few appropriately developed and validated questionnaires available. The authors conducted a systematic review to identify all tools used to measure patient satisfaction with anesthesia, which have undergone a psychometric development and validation process, appraised the quality of these processes, and made recommendations of tools that may be suitable for use in different clinical and academic settings. There are a number of robustly developed and subsequently validated instruments, however, there are still many studies using nonvalidated instruments or poorly developed tools, claiming to accurately assess satisfaction with anesthesia. This can lead to biased and inaccurate results. Researchers in this field should be encouraged to use available validated tools, to ensure that patient satisfaction is measured and reported fairly and accurately.