bluuebunny/crossref_metadata_2025 huggingface dataset:
Nuclear RNA surveillance: role of TRAMP in controlling exosome specificity
Authors: Schmidt Karyn , Butler J. Scott
Published: February 2013

The advent of high‐throughput sequencing technologies has revealed that pervasive transcription generates RNAs from nearly all regions of eukaryotic genomes. Normally, these transcripts undergo rapid degradation by a nuclear RNA surveillance system primarily featuring the RNA exosome. This multimeric protein complex plays a critical role in the efficient turnover and processing of a vast array of RNAs in the nucleus. Despite its initial discovery over a decade ago, important questions remain concerning the mechanisms that recruit and activate the nuclear exosome. Specificity and modulation of exosome activity requires additional protein cofactors, including the conserved TRAMP polyadenylation complex. Recent studies suggest that helicase and RNA‐binding subunits of TRAMP direct RNA substrates for polyadenylation, which enhances their degradation by Dis3/Rrp44 and Rrp6, the two exosome‐associated ribonucleases. These findings indicate that the exosome and TRAMP have evolved highly flexible functions that allow recognition of a wide range of RNA substrates. This flexibility provides the nuclear RNA surveillance system with the ability to regulate the levels of a broad range of coding and noncoding RNAs, which results in profound effects on gene expression, cellular development, gene silencing, and heterochromatin formation. This review summarizes recent findings on the nuclear RNA surveillance complexes, and speculates upon possible mechanisms for TRAMP‐mediated substrate recognition and exosome activation. WIREs RNA 2013, 4:217–231. doi: 10.1002/wrna.1155

This article is categorized under:

RNA Processing > 3' End Processing

RNA Processing > Processing of Small RNAs

RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms
The role ofApodemusmice andMicrotusvoles in the diet of the Tengmalm's owl in Central Europe
Authors: Zárybnická Markéta , Riegert Jan , Št'astný Karel
Published: February 2013

Based on a long‐term dataset (1999–2010), we investigated how the availability of main prey affects the breeding density and food ecology of the Tengmalm's owl (Aegolius funereus) in the Czech Republic. In particular, we assessed the role ofMicrotusvoles andApodemusmice in the diet, based on the main predictions of the optimal diet theory that the diet composition depends on the availability of the main prey. We found that (i) the Tengmalm's owl exhibited no numerical response to the availability ofMicrotusvoles andApodemusmice in the field; (ii) the availability ofApodemusmice in the field positively affected their proportion in the diet (26 %), and despite a high proportion ofMicrotusvoles in the owls’ diet (47 %), no relationship was found between their availability in the field and proportion in the diet; (iii) the proportion ofApodemusmice was negatively correlated to the proportion ofMicrotusvoles,Sorexshrews and birds in the diet, but no similar relationship was detected forMicrotusvoles; (iv) the reproductive output of Tengmalm's owls was positively correlated to the proportion ofApodemusmice in the diet, as well as toApodemusmice andMicrotusvole availability in the field; and (v) diet diversity and diet overlap were not significantly affected by the abundance ofApodemusmice andMicrotusvoles. Therefore, the validity of these main optimal diet theory predictions was not confirmed, especially forMicrotusvole prey, due to an opportunistic choice betweenApodemusmice andMicrotusvoles. We suggest that the reproductive output of nocturnal raptors in Central Europe may be less dependent onMicrotusvole supply than that of their northern counterparts.
Superior Vena Cava Syndrome: Role of the Interventionalist
Authors: Rachapalli Vamsidhar , Boucher Louis-Martin
Published: February 2013

Superior vena cava syndrome results from the obstruction of blood flow through the superior vena cava and is most often due to thoracic malignancy. However, benign etiologies are on the rise secondary to more frequent use of intravascular devices such as central venous catheters and pacemakers. Although rarely a medical emergency, the symptoms can be alarming, particularly to the patient. Traditionally, superior vena cava syndrome has been managed with radiotherapy and chemotherapy. But interventional endovascular techniques have made inroads that offer a safe, rapid, and durable response. In many cases, it may be the only reasonable treatment. Because of this, an approach to endovascular treatment of this condition must be in the armamentarium of the interventional radiologist. This review will provide the reader with an insight into the etiology, pathophysiology, and various management principles of superior vena cava syndrome. The focus will be on understanding the techniques used during various endovascular interventions, including angioplasty, stenting, and pharmacomechanical thrombolysis. Discussion will also be centred on possible complications and current evidence as well as controversies regarding these approaches.
Identification of residues important for the catalysis, structure maintenance, and substrate specificity of yeast 3‐hydroxyacyl‐CoA dehydratase Phs1
Authors: Yazawa Tomoyo , Naganuma Tatsuro , Yamagata Maki , Kihara Akio
Published: February 2013

Yeast Phs1 is a 3‐hydroxyacyl‐CoA dehydratase involved in very long‐chain fatty acid elongation. In the present study, we biochemically characterized Phs1 mutants with Ala‐substitution at each of seven highly conserved amino‐acid residues. All mutants exhibited reduced Phs1 activity. The E60A, Q79A, and R141A mutants were sensitive to digitonin, indicative of their reduced structural integrity. The fatty acid elongation cycle was greatly inhibited in the R83A, R141A, and G152A mutant membranes. The enzyme kinetics study implicated the direct involvement of the Arg83 and Gly152 residues in the catalytic process. The E60A mutation was found to affect the substrate specificity.
Mechanism of Hsp104/ClpB inhibition by prion curing Guanidinium hydrochloride
Authors: Kummer Eva , Oguchi Yuki , Seyffer Fabian , Bukau Bernd , Mogk Axel
Published: February 2013

The Saccharomyces cerevisiae AAA+ protein Hsp104 and its Escherichia coli counterpart ClpB cooperate with Hsp70 chaperones to refold aggregated proteins and fragment prion fibrils. Hsp104/ClpB activity is regulated by interaction of the M‐domain with the first ATPase domain (AAA‐1), controlling ATP turnover and Hsp70 cooperation. Guanidinium hydrochloride (GdnHCl) inhibits Hsp104/ClpB activity, leading to prion curing. We show that GdnHCl binding exerts dual effects on Hsp104/ClpB. First, GdnHCl strengthens M‐domain/AAA‐1 interaction, stabilizing Hsp104/ClpB in a repressed conformation and abrogating Hsp70 cooperation. Second, GdnHCl inhibits continuous ATP turnover by AAA‐1. These findings provide the mechanistic basis for prion curing by GdnHCl.
Pressure statistics in self-similar freely decaying isotropic turbulence
Authors: Meldi Marcello , Sagaut Pierre
Published: February 2013

The time evolution of pressure statistics in freely decaying homogeneous isotropic turbulence (HIT) is investigated via eddy-damped quasi-normal Markovian (EDQNM) computations. The present results show that the time decay rate of pressure-based statistical quantities, such as pressure variance and pressure gradient variance, are sensitive to the breakdown of permanence of large eddies. New formulae for the associated time-decay exponents are proposed, which extend previous relations proposed in Lesieur, Ossia & Metais (Phys. Fluids, vol. 11, 1999, p. 1535). Particular attention is paid to finite-Reynolds-number (FRN) effects on the pressure spectrum and pressure statistics. The results also suggest that $R{e}_{\lambda } = O(1{0}^{4} )$ must be considered to observe a one-decade inertial range in the pressure spectrum with Kolmogorov $- 7/ 3$ scaling. This threshold value is larger than almost all existing direct numerical simulation (DNS) and experimental data, justifying the discussion about other possible scaling laws. The $- 5/ 3$ slope reported in some DNS data is also recovered by the EDQNM model, but it is observed to be a low-Reynolds-number effect. Another important result is that FRN effects yield a departure from asymptotic theoretical behaviours which appear similar to some effects attributed to intermittency by most authors. This is exemplified by the ratio between pressure-based and velocity-based Taylor microscales. Therefore, high-Reynolds-number DNS or experiments such that $R{e}_{\lambda } = O(1{0}^{4} )$ would be required in order to remove FRN effects and to analyse pure intermittency effects.
Lagrangian accelerations of particles in superfluid turbulence
Authors: La Mantia M. , Duda D. , Rotter M. , Skrbek L.
Published: February 2013

Quantum turbulence in thermal counterflow of superfluid ${\text{} }^{4} \mathrm{He} $ is studied at length scales comparable to the mean distance $\ell $ between quantized vortices. The Lagrangian dynamics of solid deuterium particles, of radius ${R}_{p} $ about one order of magnitude smaller than $\ell $, is analysed in a planar section of the experimental volume by using the particle tracking velocimetry technique. We show that the average amplitude of the acceleration of the particles seems to increase as the temperature decreases and applied heat flux increases and this can be explained by exploiting the two-fluid model of superfluid ${\text{} }^{4} \mathrm{He} $. We also report that, at the probed length scales, the normalized distribution of the acceleration of the particles appears to follow an unexpected classical-like behaviour.
Novel nutritional substrates in surgery
Authors: Buijs Nikki , Wörner Elisabeth A. , Brinkmann Saskia J. H. , Luttikhold Joanna , van der Meij Barbara S. , Houdijk Alexander P. J. , van Leeuwen Paul A. M
Published: February 2013

Pharmaco-nutrients have beneficial effects on protective and immunological mechanisms in patients undergoing surgery, which are important for recovery after injury and in combating infectious agents. The aim of this review article was to outline the potential of the administration of nutritional substrates to surgical patients and the underlying mechanisms that make them particularly important in peri-operative care. Surgery causes a stress response, which has catabolic effects on the body's substrate stores. The amino acid glutamine is a stimulating agent for immune cells. It activates protective mechanisms through its role as a precursor for antioxidants and it improves the barrier function of the gut. Arginine also enhances the function of the immune system, since it is the substrate for T-lymphocytes. Furthermore,n-3 PUFA stabilise surgery-induced hyper-inflammation. Taurine is another substrate that may counteract the negative effects of surgical injury on acid–base balance and osmotic balance. These pharmaco-nutrients rapidly become deficient under the influence of surgical stress. Supplementation of these nutrients in surgical patients may restore their protective and immune-enhancing actions and improve clinical outcome. Moreover, pre-operative fasting is still common practice in the Western world, although fasting has a negative effect on the patient's condition and the recovery after surgery. This may be counteracted by a simple intervention such as administering a carbohydrate-rich supplement just before surgery. In conclusion, there are various nutritional substrates that may be of great value in improving the condition of the surgical patient, which may be beneficial for post-operative recovery.
Negative and positive life events are associated with small but lasting change in neuroticism
Authors: Jeronimus B. F. , Ormel J. , Aleman A. , Penninx B. W. J. H. , Riese H.
Published: February 2013

Background

High neuroticism is prospectively associated with psychopathology and physical health. However, within-subject changes in neuroticism due to life experiences (LEs) or state effects of current psychopathology are largely unexplored. In this 2-year follow-up study, four hypotheses were tested: (1) positive LEs (PLEs) decrease and negative LEs (NLEs) increase neuroticism; (2) LE-driven change in neuroticism is partly long-lasting; and (3) partly independent of LE-driven changes in anxiety/depression; and (4) childhood adversity (before age 16 years) moderates the influence of NLEs/PLEs on neuroticism scores in adult life.

Method

Data came from the Netherlands Study of Depression and Anxiety [NESDA, n = 2981, mean age 41.99 years (s.d. = 13.08), 66.6% women]. At follow-up (T2) we assessed PLEs/NLEs with the List of Threatening Experiences (LTE) over the prior 24 months and categorized them over recent and distant PLE/NLE measures (1–3 and 4–24 months prior to T2 respectively) to distinguish distant NLE/PLE-driven change in trait neuroticism (using the Dutch version of the Neuroticism–Extroversion–Openness Five Factor Inventory, NEO-FFI) from state deviations due to changes in symptoms of depression (self-rated version of the 30-item Inventory of Depressive Symptomatology, IDS-SR30) and anxiety (Beck Anxiety Inventory, BAI).

Results

Distant NLEs were associated with higher and distant PLEs with lower neuroticism scores. The effects of distant LEs were weak but long-lasting, especially for distant PLEs. Distant NLE-driven change in neuroticism was associated with change in symptoms of anxiety/depression whereas the effect of distant PLEs on neuroticism was independent of any such changes. Childhood adversity weakened the impact of distant NLEs but enhanced the impact of distant PLEs on neuroticism.

Conclusions

Distant PLEs are associated with small but long-lasting decreases in neuroticism regardless of changes in symptom levels of anxiety/depression. Long-lasting increases in neuroticism associated with distant NLEs are mediated by anxiety/depression.
On the Optimal Mix of Private and Common Property
Authors: Epstein Richard A.
Published: February 2013

A broad range of intellectual perspectives may be brought to bear on any important social institution. To this general rule, the institution of private property is no exception. The desirability of private property has been endlessly debated across the disciplines: philosophical, historical, economic, and legal. Yet there is very little consensus over its proper social role and limitations. Is it possible to find a unique solution to questions of property and private ownership, good for all resources and for all times? The famous defense of private property that is found in chapter 5 of John Locke'sSecond Treatise of Governmentanswers this question in the affirmative, for Locke writes as though all property was given to mankind in common, and then seeks to find the quickest and most expeditious way to convert all common property into private property. His implicit, but undefended, assumption is that common forms of property are both undesirable and unstable, while private forms of ownership are always just the opposite. Yet his preferred method for moving from a commons to a regime of private property—the unilateral decision to appropriate by each actor—is one that has been frequently condemned as a sop to unbridled egotism, even though it is subject to two constraints: the first against waste, and the second requiring the appropria-tor to leave “enough, and as good” for others.
THE HOLISTIC TRUTH OF MEMORY AND TESTIMONY INTHE RING AND THE BOOK
Authors: Addcox J. Stephen
Published: February 2013

The questions thatThe Ring and Book(1868–69) raises regarding truth, perception, and testimony have long concerned critics. However, few critics have given particular focus to the role that memory plays in the poem. WhileThe Ring and the Bookwas not the first piece of literature to offer different narrations of the same event, Robert Browning's introduction of at least ten iterations or perspectives (depending on how you count) of the same narrative within one work remains unique. The legal system is very much in view throughout the text of the poem, and so the nature of testimony as a component of the legal process is integral to our consideration ofThe Ring and the Book. Specifically, shifting attitudes about legal testimony in the nineteenth century make memory particularly important for any study of testimony in the poem. In his multivolume workThe Rationale of Judicial Evidence(1827), Jeremy Bentham gives special consideration to the composition of testimony, which he argues consists of four elements: perception, judgment, memory, and expression (155). Bentham's work recognized that testimony was not a simple matter of truth and falsehood, but that the faculties of the witness were intimately intertwined with testimony. However, contemporary critics have tended to focus on perception and expression (language), while memory has remained mostly unexamined.
The Relationship between Perfectionism and Rumination in Post Traumatic Stress Disorder
Authors: Egan Sarah J. , Hattaway Mary , Kane Robert T.
Published: February 2013

Background: To date no research has investigated the link between Post Traumatic Stress Disorder (PTSD) and perfectionism in a clinical sample. Aims: The aim of the current study was to examine whether there is a relationship between PTSD and perfectionism. This is important to address as many studies have demonstrated a link between other anxiety disorders, eating disorders, depression and perfectionism. The research also aimed to examine whether rumination was a mediator of the relationship between PTSD and perfectionism. Method: The sample consisted of 30 participants who were currently in treatment for PTSD. Results: The results suggest that perfectionism and PTSD symptoms were significantly correlated. In addition, rumination was a significant mediator of the relationship between Concern over Mistakes and PTSD. Conclusions: These findings help increase understanding about the relationships of perfectionism and rumination in PTSD and have implications for the treatment of PTSD.
CREDIT FRICTIONS, COLLATERAL, AND THE CYCLICAL BEHAVIOR OF THE FINANCE PREMIUM
Authors: Agénor Pierre-Richard , Bratsiotis George J. , Pfajfar Damjan
Published: February 2013

This paper examines the behavior of the finance premium after technology and monetary shocks in a dynamic stochastic general equilibrium (DSGE) model where borrowers use a fraction of their production (output) as collateral. We show that this simple framework is capable of producing a countercyclical finance premium, while matching the well-documented stylized facts of macro dynamics. A key feature is the endogenous derivation of the default probability from break-even conditions, which results in the loan rate being set as a countercyclical finance premium over the cost of borrowing from the central bank. The latter is shown to provide an accelerator effect through which shocks can amplify the loan spread and the dynamic response of macro variables.
ON THE CYCLICALITY OF CREDIT
Authors: Demirel Ufuk Devrim
Published: February 2013

This study documents the cyclical properties of business credit in the United States and in the Euro area and constructs a theoretical model that can successfully replicate the observed characteristics. I find that real business loans lag output; i.e., business credit is more strongly correlated with past output than with current output. Furthermore, real business loans correlate negatively with future output and investment and positively with past output and investment. I show that a fairly standard model of business and credit fluctuations with agency costs can neither generate the lagging behavior of business credit nor induce the observed cross-correlation patterns of output, investment, and business loans. I introduce a costly financial intermediation mechanism into an otherwise standard macroeconomic framework and show that the evolution of intermediary balance sheets and the interaction of intermediation and agency costs can induce the observed regularities.
Lateralization of semantic processing is shaped by exposure to specific mother tongues: The case of insight problem solving by bilingual and monolingual native Hebrew speakers
Authors: METUKI NILI , SINKEVICH SHANI , LAVIDOR MICHAL
Published: February 2013

Solving insight problems is a complex task found to involve coarse semantic processing in the right hemisphere when tested in English. In Hebrew, the left hemisphere (LH) may be more active in this task, due to the inter-hemispheric interaction between semantic, phonological and orthographic processing. In two Hebrew insight problems experiments, we revealed a performance advantage in the LH, in contrast to the patterns previously observed in English. A third experiment, conducted in English with early Hebrew–English bilinguals, confirmed that the LH advantage found with Hebrew speakers does not depend on specific task requirements in Hebrew. We suggest that Hebrew speakers show redundancy between the hemispheres in coarse semantic processing in handling frequent lexical ambiguities stemming from the orthographic structure in Hebrew. We further suggest that inter-hemispheric interactions between linguistic and non-linguistic processes may determine the hemisphere in which coarse coding will take place. These findings highlight the possible effect of exposure to a specific mother tongue on the lateralization of processes in the brain, and carries possible theoretical and methodological implications for cross-language studies.
Regulation of cholinergic activity by the vesicular acetylcholine transporter
Authors: Prado Vania F. , Roy Ashbeel , Kolisnyk Benjamin , Gros Robert , Prado Marco A. M.
Published: February 2013

Acetylcholine, the first chemical to be identified as a neurotransmitter, is packed in synaptic vesicles by the activity of VAChT (vesicular acetylcholine transporter). A decrease in VAChT expression has been reported in a number of diseases, and this has consequences for the amount of acetylcholine loaded in synaptic vesicles as well as for neurotransmitter release. Several genetically modified mice targeting the VAChT gene have been generated, providing novel models to understand how changes in VAChT affect transmitter release. A surprising finding is that most cholinergic neurons in the brain also can express a second type of vesicular neurotransmitter transporter that allows these neurons to secrete two distinct neurotransmitters. Thus a given neuron can use two neurotransmitters to regulate different physiological functions. In addition, recent data indicate that non-neuronal cells can also express the machinery used to synthesize and release acetylcholine. Some of these cells rely on VAChT to secrete acetylcholine with potential physiological consequences in the periphery. Hence novel functions for the oldest neurotransmitter known are emerging with the potential to provide new targets for the treatment of several pathological conditions.
Clustering algorithm for non‐uniformly distributed nodes in wireless sensor network
Authors: Tripathi R.K. , Singh Y.N. , Verma N.K.
Published: February 2013

Balancing energy consumption of sensor nodes and increasing network lifetime are the two important objectives for wireless sensor networks. Sensor nodes distribution in a topology affect the energy consumption of individual nodes as well as the wireless sensor network because the nodes at different locations will have different energy loss due to different distances from the base station. This reported work focuses on energy efficient clustering for practical non‐uniformly deployed sensor nodes in a wireless sensor network.
The SC EXCELL model for prediction of rain attenuation on terrestrial radio links
Authors: Luini L. , Capsoni C.
Published: February 2013

The SC EXCELL (Stratiform/Convective EXponential CELL) model, originally devised for the prediction of the complementary cumulative distribution function of rain attenuation (henceforth P(A)) on Earth‐space radio links, is tested here in its ability to predict also the P(A) on terrestrial links. Thanks to its physical soundness in representing the rainfall environment, the proposed method does not require any calibration procedure on existing data, as is typically the case of most of the semi‐empirical models proposed so far. When tested against the global DBSG3 database made available by the International Telecommunication Union – Radiocommunication Sector (ITU‐R), the proposed model shows an improvement in the prediction accuracy with respect to the method currently recommended by the ITU‐R.
CMOS 45 GHz vector modulator with gain/phase correction through calibration
Authors: Juntunen E. , Dawn D. , Laskar J. , Papapolymerou J.
Published: February 2013

A 45 GHz vector modulator designed in 45 nm SOI CMOS is presented along with an open‐loop calibration technique for gain/phase correction. The continuous 360° vector modulator consists of a passive quadrature signal generation network followed by a Gilbert cell modulator. The simple, open‐loop calibration procedure results in RMS gain and phase errors less than 0.5 dB and 5°, respectively. The circuit consumes 18 mW of DC power from a 1 V supply.
Effect of buffer cache on storage performance in virtualised environment
Authors: Park Hyunchan , Yoo Chuck
Published: February 2013

Many researches compare the storage performance of different virtualised systems. Some of their results are unexplained, which reduces the reliability of the storage performance comparison itself. Through experiments, this reported work identifies that the size of buffer cache significantly affects the storage performance. When the same size of buffer cache is used in experiments, very different results are obtained from the prior results because they did not take the size of buffer cache into account. The new results make more sense with the characteristics of virtualised environments.
60 GHz CMOS downconversion mixer with 15.46 dB gain and 64.7 dB LO‐RF isolation
Authors: Lee J.H. , Lin Y.S.
Published: February 2013

A 60 GHz double‐balanced mixer for direct downconversion using standard 90 nm CMOS technology is reported. The downconversion mixer comprises a double‐balanced Gilbert cell with a current‐reused RF single‐to‐differential converter for conversion gain (CG) enhancement, a Marchand balun for converting the single LO input signal to a differential signal, and a baseband amplifier. The mixer consumes 17 mW and achieves a low noise figure of 12.8 dB at 60 GHz. In addition, the mixer achieves excellent LO‐RF isolation of 64.7 dB, LO‐IF isolation of 51.5 dB, and RF‐IF isolation of 59.5 dB at an RF of 60 GHz and LO of 59.9 GHz. At IF of 0.1 GHz, the mixer achieves maximum CG of 15.46 dB at an RF of 62 GHz, and CG of 14.7 dB at an RF of 60 GHz, which are believed to be the best CG results ever reported for a 60 GHz active CMOS downconversion mixer.
Balanced pulse generator for ultra‐wideband radar application
Authors: Xia Xinfan , Liu Lihua , Guan Hongfei , Fang Guangyou
Published: February 2013

A balanced pulse generator with high voltage amplitude and pulse width in the picoseconds region is described. It can operate well at the pulse repetition frequency (PRF) up to 500 kHz. The proposed generator contains four NPN silicon power transistors operating in avalanche mode and a pair of pulse shaping circuits which effectively utilise the transition characteristics of a step recovery diode. Measurement results are presented, which show the output of the generator are balanced pulses with peak values of ±46 V at 100 kHz PRF and approximately 330 ps full‐width at half‐maximum in width.
Two‐step incremental analogue‐to‐digital converter
Authors: Chen C.‐H. , Zhang Y. , Jung Y. , He T. , Ceballos J.L. , Temes G.C.
Published: February 2013

A new incremental ADC (IADC) is proposed which extends the order of a conventional incremental ADC from N to (2N − 1) by way of a two‐step operation. For a given conversion time, the duration of each step can be optimised. For an Nth‐order IADC, the performance is equivalent to that of a (2N − 1)‐order converter. However, it only needs the same circuitry as the Nth‐order one. The new IADC is hence more accurate, and also much more power‐efficient than the conventional ones.
Making use of x-ray optical effects in photoelectron-, Auger electron-, and x-ray emission spectroscopies: Total reflection, standing-wave excitation, and resonant effects
Authors: Yang S.-H. , Gray A. X. , Kaiser A. M. , Mun B. S. , Sell B. C. , Kortright J. B. , Fadley C. S.
Published: February 2013

We present a general theoretical methodology and related open-access computer program for carrying out the calculation of photoelectron, Auger electron, and x-ray emission intensities in the presence of several x-ray optical effects, including total reflection at grazing incidence, excitation with standing-waves produced by reflection from synthetic multilayers and at core-level resonance conditions, and the use of variable polarization to produce magnetic circular dichroism. Calculations illustrating all of these effects are presented, including in some cases comparisons to experimental results. Sample types include both semi-infinite flat surfaces and arbitrary multilayer configurations, with interdiffusion/roughness at their interfaces. These x-ray optical effects can significantly alter observed photoelectron, Auger, and x-ray intensities, and in fact lead to several generally useful techniques for enhancing surface and buried-layer sensitivity, including layer-resolved densities of states and depth profiles of element-specific magnetization. The computer program used in this study should thus be useful for a broad range of studies in which x-ray optical effects are involved or are to be exploited in next-generation surface and interface studies of nanoscale systems.
Luminescence and energy transfer processes in ensembles and single Mn or Tb doped ZnS nanowires
Authors: Kaiser Uwe , Gies Sebastian , Geburt Sebastian , Riedel Franziska , Ronning Carsten , Heimbrodt Wolfram
Published: February 2013

Zinc sulfide (ZnS) nanowires with a typical diameter of 100 to 300 nm have been doped with different concentrations of either Mn or Tb using ion implantation. Both systems show very efficient and long living intra-shell luminescence with strong non-exponential decay characteristics in the range of milliseconds. The time behavior of the corresponding luminescence is well described within a modified Förster model, taking into account the lower dimensionality of the nanowires in case of radiationless dipole-dipole energy transfer. The general applicability of this model for energy transfer processes in low dimensional systems will be shown as a function of concentration, temperature, excitation density as well as for measurements on the level of single nanowires.
Structural and spectroscopic study of the linear proton-bound complex of PN with HNP+
Authors: Eric Cotton C. , Francisco Joseph S. , Mitrushchenkov Alexander O.
Published: February 2013

This work reports the results of high level ab initio calculations of the PN-HNP+ complex and the corresponding hydrogen migration transition state. The geometries, rotational constants, harmonic vibrational frequencies, and energetics of each species involved in the complex are reported. A reduced dimensional 2D and 4D potential energy surface is constructed and used to obtain 2D and 4D vibrational states. The results of this study show excellent correlation to available experimental data for PN. The presented results can facilitate both laboratory and interstellar observations of this novel and strongly interacting linear proton-bound complex.
Benchmarks of improved complete basis set extrapolation schemes designed for standard CCSD(T) atomization energies
Authors: Feller David
Published: February 2013

Simple modifications of complete basis set extrapolation formulas chosen from the literature are examined with respect to their abilities to reproduce a diverse set of 183 reference atomization energies derived primarily from very large basis set standard, frozen core coupled-cluster singles, doubles plus perturbative triples (CCSD(T)) with the aug-cc-pVnZ basis sets. This reference set was augmented with a few larger chemical systems treated with explicitly correlated CCSD(T)-F12b using a quadruple zeta quality basis set followed by extrapolation to complete basis set limit. Tuning the extrapolation formula parameters for the present reference set resulted in substantial reductions in the error metrics. In the case of the best performing approach, the aVnZ extrapolated results are equivalent to or better than results obtained from raw aV(n + 3)Z basis set calculations. To the extent this behavior holds for molecules outside the reference set, it represents an improvement of at least one basis set level over the original formulations and a further significant reduction in the amount of computer time needed to accurately approximate the basis set limit.
A strategy for calibrating the actual quantum efficiency of quantum cutting in YVO4:Bi3+(Nd3+), Yb3+
Authors: Xu Sai , Xu Wen , Zhu Yongsheng , Dong Biao , Bai Xue , Xu Lin , Song Hongwei
Published: February 2013

Recently, much attention has been paid to the quantum cutting (QC) through the energy transfer (ET) between Yb3+ and other RE ions and the theoretical quantum efficiency (QE) of QC was reported as high as 140%–195%. However, the practical measurement was rather rare. In this paper, we studied the ET and QC properties of YVO4: Bi3+ (5%)/Nd3+ (1%), Yb3+ (0%–20%) synthesized by the solvothermal method. And more, a strategy for calibrating the actual QE of QC was established. Through measurement, the highest QE of QC was determined to be 12.3% for YVO4: Bi3+,Yb3+, and 25.8% for YVO4: Nd3+,Yb3+, which was much lower than the prediction by luminescent dynamics. This work helps us to forecast the feasibility of potential application in enhancing the efficiency of Si-based solar cell via the Bi3+/RE3+ codoped with Yb3+ phosphors.
Application of smooth exterior scaling method to calculate the high harmonic generation spectra
Authors: Kalita Dhruba J. , Gupta Ashish K.
Published: February 2013

We have calculated the high harmonic generation spectra from Xe atom by imposing different kinds of absorbing potentials. Owing to the center of inversion of the model system, one should get odd harmonics only. However, using negative imaginary potentials as an absorbing boundary condition, we have also got even order harmonics along with the odd order harmonics. These non-odd order harmonics are generated due to the spurious reflections occurring at the grid boundary. On the contrary, when smooth exterior scaling methods are used as an absorbing boundary condition, only odd order harmonics are obtained. Hence, smooth exterior scaling methods impose proper absorbing boundary condition.
Ge1−xMnx heteroepitaxial quantum dots: Growth, morphology, and magnetism
Authors: Kassim J. , Nolph C. , Jamet M. , Reinke P. , Floro J.
Published: February 2013

Heteroepitaxial Ge1-xMnx quantum dots (QDs) were grown on Si (001) by molecular beam epitaxial co-deposition, with x = 0 to 0.10, in order to explore the interaction between Mn content, surface morphological evolution, and magnetism. Morphological evolution typical of the Ge/Si (001) system was observed, where the effect of Mn on surface morphology is surprisingly minimal at low Mn content, with no obvious surface morphological indicators of second phase formation. As the Mn content increases, secondary phase formation becomes evident, appearing to heterogeneously nucleate on or within Ge QDs. Still higher Mn concentrations lead to extensive second phase formation interspersed with an array of Ge QDs. Although ferromagnetism up to 220 K is observed, likely arising from intermetallic precipitates, there is no clear evidence for room-temperature ferromagnetism associated with a dilute magnetic solution phase.
Influence of manganese doping to the full tensor properties of 0.24Pb(In1/2Nb1/2)O3-0.47Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystals
Authors: Sun Enwei , Zhang Rui , Wu Fengmin , Yang Bin , Cao Wenwu
Published: February 2013

Complete sets of elastic, piezoelectric, dielectric, and electromechanical properties of [001]c and [011]c poled pure and 0.5 wt. % manganese-doped 0.24Pb(In1/2Nb1/2)O3-0.47Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystals have been characterized at room temperature. The results indicate that manganese ion substitution in the B-site of perovskite 0.24PIN-0.47PMN-0.29PT single crystals makes the material harder with much higher mechanical quality factor Qm and slight decrease in piezoelectric and dielectric constants. The much improved Qm value (200–900) makes Mn-doped single crystals more suitable for high-power transducer applications than pure single crystals.
Note: Signal amplification and filtering with a tristable stochastic resonance cantilever
Authors: Lu Siliang , He Qingbo , Zhang Haibin , Zhang Shangbin , Kong Fanrang
Published: February 2013

This Note reports a tristable cantilever that exploits stochastic resonance (SR) phenomenon for a study of signal amplification and filtering. The tristable device system combines the benefits of bistable system (wide interwell spacing) and monostable system (smooth motion in potential). The prototype tristable cantilever exhibits 42 times root-mean-square amplitude, 35.86 dB power gain, advance of 15 dB signal-to-noise ratio, and twice fidelity at around 7.6 Hz as compared to the input signal. In a wide operating bandwidth [5.5 Hz, 8.2 Hz], the tristable SR cantilever outperforms the traditional monostable cantilever and bistable SR cantilever in these characteristics.
Quantitative scanning thermal microscopy of ErAs/GaAs superlattice structures grown by molecular beam epitaxy
Authors: Park K. W. , Nair H. P. , Crook A. M. , Bank S. R. , Yu E. T.
Published: February 2013

A proximal probe-based quantitative measurement of thermal conductivity with ∼100–150 nm lateral and vertical spatial resolution has been implemented. Measurements on an ErAs/GaAs superlattice structure grown by molecular beam epitaxy with 3% volumetric ErAs content yielded thermal conductivity at room temperature of 9 ± 2 W/m K, approximately five times lower than that for GaAs. Numerical modeling of phonon scattering by ErAs nanoparticles yielded thermal conductivities in reasonable agreement with those measured experimentally and provides insight into the potential influence of nanoparticle shape on phonon scattering. Measurements of wedge-shaped samples created by focused ion beam milling provide direct confirmation of depth resolution achieved.
Photoresponses of manganese-doped gallium nitride grown by metalorganic vapor-phase epitaxy
Authors: Sheu Jinn-Kong , Huang Feng-Wen , Liu Yu-Hsuan , Chen P. C. , Yeh Yu-Hsiang , Lee Ming-Lun , Lai Wei-Chih
Published: February 2013

The photoresponses of gallium nitride (GaN) doped with manganese (Mn) grown by metalorganic vapor-phase epitaxy were investigated. The transmission spectroscopy obtained from the Mn-doped GaN exhibited three distinct absorption thresholds at approximately 365, 650, and 830 nm, respectively. The below-band-gap absorption peaks were attributed to the fact that the deep Mn-related states mediate the electronic transition between the valence and conduction bands. A below-band-gap spectral response ranging from 400 nm to 1000 nm was also observed from a typical GaN p-i-n photodetector with Mn-doped absorption layer. The significant below-band-gap spectral responses showed that the Mn-doped GaN-based materials have promising applications in intermediate band solar cells.
Spin polarized current through Cu-DNA modulated by a gate voltage
Authors: Kang D. W. , Hao X. P. , Li X. Z. , Li L. B. , Xie S. J.
Published: February 2013

Spin polarized current through DNA molecule doped with one Cu2+ ion is studied. It is found that the spin polarization is sensitive to the position of the Cu2+ ion doping. In order to obtain a steady and large spin polarization, the metal ion should be doped at the end of the DNA molecule. We propose the possibility of controlling the spin polarization using a gate voltage. This control is originated from electron precession, which is induced by Rashba spin-orbit coupling.
What is Wrong with Virtual Water Trading? On the Limitations of the Virtual Water Concept
Authors: Gawel Erik , Bernsen Kristina
Published: February 2013

Virtual water, the amount of water used along a good's value chain, has come under discussion. Fairness and efficiency problems are seen to arise in the reallocation of access to water resources through the means of international trade. Moral issues are attached to both imports and exports, and even to a country's own consumption of virtual water. Global institutional arrangements have therefore been suggested to regulate virtual water trade both efficiently and ‘fairly’. With this paper we will provide a short overview of the concept's history and findings, and an analysis from the perspective of economic trade theory, bringing up the old debate about the economic and environmental merits of free trade. The contribution of this paper will be to examine the performance of virtual water concepts in advising business or policy decisions in the form of global governance arrangements. It must be concluded that the virtual water concept is limited in terms of its usefulness in providing policy advice. The usually applied normative criteria are inconsistent, implying governance schemes that improve neither efficiency nor sustainability Water-related problems should be solved in the respective arenas and not by global governance schemes or trade barriers.
Getting Access to Water: Property Rights or Public Policy Strategies?
Authors: Aubin David , Varone Frédéric
Published: February 2013

Water is subject to heterogeneous uses that put pressure on it and create rivalries between competing users. With this paper we analyse the conditions under which challengers are successful in gaining access to the resource and in imposing a change of behaviour on the incumbent users. We ask whether the acquisition of property rights is the only means for a challenger to get access to the resource. The empirical study compares eleven ‘most different’ cases of water rivalries in four water basins. We show that two main ‘paths’ explain success: either the challenger activates a property right and negotiates a solution at no cost for the incumbents or he or she activates a public policy that grants him or her a credible alternative to a negotiated agreement. Thus, the challenger must select the kind of rule, property right, or public policy that supports their position and then elaborate an appropriate strategy to impose this rule.
Evaluating the Impact of Different Training Methods on SME Business Performance
Authors: Jones Paul , Beynon Malcolm J , Pickernell David , Packham Gary
Published: February 2013

With this study we evaluate the impact of different training methods (TMs) on small and medium-enterprises' (SMEs') business performances, utilising a dataset of 3521. We consider the relationship between the satisfaction SMEs have towards their employees' training needs being met by a diverse range of TMs and the levels of impact the training has had on business performance. To investigate both the interdependence and dependence of satisfaction levels of training needs met with business performance, we undertake bivariate correlations and multivariate regression-type analyses (using Regression-type Classification and Ranking Belief Simplex). The results presented offer novel insights into the relationships between TMs and business performance.
Grouping by Form in Young Infants: Only Relevant Variability Promotes Perceptual Learning
Authors: Quinn Paul C , Bhatt Ramesh S
Published: February 2013

Infants do not readily organize visual pattern information using form similarity: 3 to 4 month olds familiarized with arrays consisting of alternating columns or rows of a given element contrast do not display a subsequent preference for a novel organization of horizontal versus vertical bars. However, when array types composed of different element contrasts are presented during familiarization, infants perform successfully, indicating that variability in pattern information depicting an invariant structure promotes perceptual learning. In the current investigation, we examined whether the type of variability (relevant versus irrelevant) impacts this learning, as a way to understand the specificity and mechanism underlying the learning. In experiment 1, one group of infants (relevant variability) was familiarized with three element contrasts forming column-row arrays on different trials, and a fourth element contrast that formed an outer enclosing context on all trials. For the other group (irrelevant variability), the column-row array was composed of the same element contrast across trials, while the outer context differed across trials by being composed of three different element contrasts. Only the relevant variability group performed successfully. Experiment 2 showed that the failure of irrelevant variation to facilitate organization was not due to insensitivity to the variation among elements in the outer context. The findings suggest that variation which emphasizes global structure and deemphasizes local element information is a significant factor in facilitating perceptual learning.
History, distribution and uses.
Authors: Bost J. B. , Smith N. J. H. , Crane J. H.
Published: February 2013

This chapter focuses on the evolutionary history and distribution of avocado from the remote past to the present. The worldwide production, various uses of the plant and its fruits and its composition are also discussed.
Taxonomy and botany.
Authors: Chanderbali A. S. , Soltis D. E. , Soltis P. S. , Wolstenholme B. N.
Published: February 2013

This chapter focuses on taxonomy of the genus Persea, including keys to the species. The gross morphology, architecture and growth habit of the cultivated avocado tree is also discussed as a basis for a better understanding of tree management and manipulation.
Ecology: climate and soils.
Authors: Wolstenholme B. N.
Published: February 2013

This chapter gives an overview of climatic and soil variables that determine where various types of avocados can be successfully grown. The importance of stress minimization of stress to achieve commercial viability, climate and soil selection and Phytophthora root rot resistance are discussed and the risks posed by high rain hazards and less than adequately drained soils to the long-term viability of avocado orchards are presented.
Insect and mite pests.
Authors: Peña J. E. , Hoddle M. S. , Aluja M. , Palevsky E. , Ripa R. , Wysoki M.
Published: February 2013

Insect and mite pests. This chapter describes the most common pests of avocado in different growing areas of the world. Some current pest management methodologies are also presented..
Harvesting, packing, postharvest technology, transport and processing.
Authors: Hofman P. J. , Bower J. , Woolf A.
Published: February 2013

This chapter provides updated information on avocado fruit quality parameters, sensory perception and maturity, production and postharvest factors affecting quality defects, disinfestation and storage (including pre-conditioning), predicting outturn quality and processing.