bluuebunny/crossref_metadata_2025 huggingface dataset:
Reestablishment of ion homeostasis during chill-coma recovery in the cricketGryllus pennsylvanicus
Authors: MacMillan Heath A. , Williams Caroline M. , Staples James F. , Sinclair Brent J.
Published: November 2012

The time required to recover from cold-induced paralysis (chill-coma) is a common measure of insect cold tolerance used to test central questions in thermal biology and predict the effects of climate change on insect populations. The onset of chill-coma in the fall field cricket (Gryllus pennsylvanicus, Orthoptera: Gryllidae) is accompanied by a progressive drift of Na+and water from the hemolymph to the gut, but the physiological mechanisms underlying recovery from chill-coma are not understood for any insect. Using a combination of gravimetric methods and atomic absorption spectroscopy, we demonstrate that recovery from chill-coma involves a reestablishment of hemolymph ion content and volume driven by removal of Na+and water from the gut. Recovery is associated with a transient elevation of metabolic rate, the time span of which increases with increasing cold exposure duration and closely matches the duration of complete osmotic recovery. Thus, complete recovery from chill-coma is metabolically costly and encompasses a longer period than is required for the recovery of muscle potentials and movement. These findings provide evidence that physiological mechanisms of hemolymph ion content and volume regulation, such as ion-motive ATPase activity, are instrumental in chill-coma recovery and may underlie natural variation in insect cold tolerance.
Application of an optogenetic byway for perturbing neuronal activity via glial photostimulation
Authors: Sasaki Takuya , Beppu Kaoru , Tanaka Kenji F. , Fukazawa Yugo , Shigemoto Ryuichi , Matsui Ko
Published: November 2012

Dynamic activity of glia has repeatedly been demonstrated, but if such activity is independent from neuronal activity, glia would not have any role in the information processing in the brain or in the generation of animal behavior. Evidence for neurons communicating with glia is solid, but the signaling pathway leading back from glial-to-neuronal activity was often difficult to study. Here, we introduced a transgenic mouse line in which channelrhodopsin-2, a light-gated cation channel, was expressed in astrocytes. Selective photostimulation of these astrocytes in vivo triggered neuronal activation. Using slice preparations, we show that glial photostimulation leads to release of glutamate, which was sufficient to activate AMPA receptors on Purkinje cells and to induce long-term depression of parallel fiber-to-Purkinje cell synapses through activation of metabotropic glutamate receptors. In contrast to neuronal synaptic vesicular release, glial activation likely causes preferential activation of extrasynaptic receptors that appose glial membrane. Finally, we show that neuronal activation by glial stimulation can lead to perturbation of cerebellar modulated motor behavior. These findings demonstrate that glia can modulate the tone of neuronal activity and behavior. This animal model is expected to be a potentially powerful approach to study the role of glia in brain function.
Hierarchical recruitment of phasic dopamine signaling in the striatum during the progression of cocaine use
Authors: Willuhn Ingo , Burgeno Lauren M. , Everitt Barry J. , Phillips Paul E. M.
Published: November 2012

Drug addiction is a neuropsychiatric disorder that marks the end stage of a progression beginning with recreational drug taking but culminating in habitual and compulsive drug use. This progression is considered to reflect transitions among multiple neural loci. Dopamine neurotransmission in the ventromedial striatum (VMS) is pivotal in the control of initial drug use, but emerging evidence indicates that once drug use is well established, its control is dominated by the dorsolateral striatum (DLS). In the current work, we conducted longitudinal neurochemical recordings to ascertain the spatiotemporal profile of striatal dopamine release and to investigate how it changes during the period from initial to established drug use. Dopamine release was detected using fast-scan cyclic voltammetry simultaneously in the VMS and DLS of rats bearing indwelling i.v. catheters over the course of 3 wk of cocaine self-administration. We found that phasic dopamine release in DLS emerged progressively during drug taking over the course of weeks, a period during which VMS dopamine signaling declined. This emergent dopamine signaling in the DLS mediated discriminated behavior to obtain drug but did not promote escalated or compulsive drug use. We also demonstrate that this recruitment of dopamine signaling in the DLS is dependent on antecedent activity in VMS circuitry. Thus, the current findings identify a striatal hierarchy that is instantiated during the expression of established responses to obtain cocaine.
Pain relief produces negative reinforcement through activation of mesolimbic reward–valuation circuitry
Authors: Navratilova Edita , Xie Jennifer Y. , Okun Alec , Qu Chaoling , Eyde Nathan , Ci Shuang , Ossipov Michael H. , King Tamara , Fields Howard L. , Porreca Frank
Published: November 2012

Relief of pain is rewarding. Using a model of experimental postsurgical pain we show that blockade of afferent input from the injury with local anesthetic elicits conditioned place preference, activates ventral tegmental dopaminergic cells, and increases dopamine release in the nucleus accumbens. Importantly, place preference is associated with increased activity in midbrain dopaminergic neurons and blocked by dopamine antagonists injected into the nucleus accumbens. The data directly support the hypothesis that relief of pain produces negative reinforcement through activation of the mesolimbic reward–valuation circuitry.
Late embryogenesis abundant proteins protect human hepatoma cells during acute desiccation
Authors: Li Shumin , Chakraborty Nilay , Borcar Apurva , Menze Michael A. , Toner Mehmet , Hand Steven C.
Published: November 2012

Expression of late embryogenesis abundant (LEA) proteins is highly correlated with desiccation tolerance in anhydrobiotic animals, selected land plants, and bacteria. Genes encoding two LEA proteins, one localized to the cytoplasm/nucleus (AfrLEA2) and one targeted to mitochondria (AfrLEA3m), were stably transfected into human HepG2 cells. A trehalose transporter was used for intracellular loading of this disaccharide. Cells were rapidly and uniformly desiccated to low water content (<0.12 g H
2
O/g dry weight) with a recently developed spin-drying technique. Immediately on rehydration, control cells without LEA proteins or trehalose exhibited 0% membrane integrity, compared with 98% in cells loaded with trehalose and expressing AfrLEA2 or AfrLEA3m; surprisingly, AfrLEA3m without trehalose conferred 94% protection. Cell proliferation across 7 d showed an 18-fold increase for cells dried with AfrLEA3m and trehalose, compared with 27-fold for nondried controls. LEA proteins dramatically enhance desiccation tolerance in mammalian cells and offer the opportunity for engineering biostability in the dried state.
Using phase to recognize English phonemes and their distinctive features in the brain
Authors: Wang Rui , Perreau-Guimaraes Marcos , Carvalhaes Claudio , Suppes Patrick
Published: November 2012

The neural mechanisms used by the human brain to identify phonemes remain unclear. We recorded the EEG signals evoked by repeated presentation of 12 American English phonemes. A support vector machine model correctly recognized a high percentage of the EEG brain wave recordings represented by their phases, which were expressed in discrete Fourier transform coefficients. We show that phases of the oscillations restricted to the frequency range of 2–9 Hz can be used to successfully recognize brain processing of these phonemes. The recognition rates can be further improved using the scalp tangential electric field and the surface Laplacian around the auditory cortical area, which were derived from the original potential signal. The best rate for the eight initial consonants was 66.7%. Moreover, we found a distinctive phase pattern in the brain for each of these consonants. We then used these phase patterns to recognize the consonants, with a correct rate of 48.7%. In addition, in the analysis of the confusion matrices, we found significant similarity–differences were invariant between brain and perceptual representations of phonemes. These latter results supported the importance of phonological distinctive features in the neural representation of phonemes.
Structural genes of wheat and barley 5-methylcytosine DNA glycosylases and their potential applications for human health
Authors: Wen Shanshan , Wen Nuan , Pang Jinsong , Langen Gregor , Brew-Appiah Rhoda A. T. , Mejias Jaime H. , Osorio Claudia , Yang Mingming , Gemini Richa , Moehs Charles P. , Zemetra Robert S. , Kogel Karl-Heinz , Liu Bao , Wang Xingzhi , von Wettstein Diter , Rustgi Sachin
Published: November 2012

Wheat supplies about 20% of the total food calories consumed worldwide and is a national staple in many countries. Besides being a key source of plant proteins, it is also a major cause of many diet-induced health issues, especially celiac disease. The only effective treatment for this disease is a total gluten-free diet. The present report describes an effort to develop a natural dietary therapy for this disorder by transcriptional suppression of wheatDEMETER(DME) homeologs using RNA interference.DMEencodes a 5-methylcytosine DNA glycosylase responsible for transcriptional derepression of gliadins and low-molecular-weight glutenins (LMWgs) by active demethylation of their promoters in the wheat endosperm. Previous research has demonstrated these proteins to be the major source of immunogenic epitopes. In this research, barley and wheatDMEgenes were cloned and localized on the syntenous chromosomes. Nucleotide diversity amongDMEhomeologs was studied and used for their virtual transcript profiling. Functional conservation of DME enzyme was confirmed by comparing the motif and domain structure within and across the plant kingdom. Presence and absence of CpG islands in prolamin gene sequences was studied as a hallmark of hypo- and hypermethylation, respectively. Finally the epigenetic influence ofDMEsilencing on accumulation of LMWgs and gliadins was studied using 20 transformants expressing hairpin RNA in their endosperm. These transformants showed up to 85.6% suppression inDMEtranscript abundance and up to 76.4% reduction in the amount of immunogenic prolamins, demonstrating the possibility of developing wheat varieties compatible for the celiac patients.
Stromal epigenetic dysregulation is sufficient to initiate mouse prostate cancer via paracrine Wnt signaling
Authors: Zong Yang , Huang Jiaoti , Sankarasharma Devipriya , Morikawa Teppei , Fukayama Masashi , Epstein Jonathan I. , Chada Kiran K. , Witte Owen N.
Published: November 2012

Significance

Increasing evidence supports the notion that an aberrant microenvironment facilitates cancer development. The mechanisms underlying the phenotypic changes and the tumor-promoting function of cancer-associated stroma remain largely unknown. Overexpression of the chromatin remodeling protein Hmga2 in the stroma leads to the formation of multifocal prostatic precancerous lesions in the neighboring naïve epithelium in a paracrine Wnt-dependent manner. The potent growth-promoting effects of Hmga2-modified stroma collaborate significantly with enhanced stromal AR signaling to drive the development of prostate adenocarcinoma. Our findings provide compelling evidence for the critical contribution of epigenetic changes in stromal cells to cancer initiation and progression.
Orai-STIM–mediated Ca
2
+
release from secretory granules revealed by a targeted Ca
2+
and pH probe
Authors: Dickson Eamonn J. , Duman Joseph G. , Moody Mark W. , Chen Liangyi , Hille Bertil
Published: November 2012

Significance

Elevated cytoplasmic calcium modulates many cellular responses. Two Ca
2+
sources feed most cytoplasmic Ca
2+
elevations, the extracellular space and the endoplasmic reticulum. We found that secretory granules represent another Ca
2+
source that releases Ca
2+
in a physiologically interesting way. We developed a targeted probe for monitoring Ca
2+
in secretory granules. It revealed a unique receptor-stimulated mechanism of Ca
2+
release from secretory granules apparently involving “store-operated” Orai channels in the secretory granule membrane. The channels open when reticular stores are depleted. Such Ca
2+
release from granules might elevate local Ca
2+
concentrations and aid in the refilling of other cytoplasmic Ca
2+
stores.
Transcriptional modulation of the developing immune system by early life social adversity
Authors: Cole Steven W. , Conti Gabriella , Arevalo Jesusa M. G. , Ruggiero Angela M. , Heckman James J. , Suomi Stephen J.
Published: November 2012

To identify molecular mechanisms by which early life social conditions might influence adult risk of disease in rhesus macaques (Macaca mulatta), we analyze changes in basal leukocyte gene expression profiles in 4-mo-old animals reared under adverse social conditions. Compared with the basal condition of maternal rearing (MR), leukocytes from peer-reared (PR) animals and PR animals provided with an inanimate surrogate mother (surrogate/peer reared, SPR) show enhanced expression of genes involved in inflammation, cytokine signaling, and T-lymphocyte activation, and suppression of genes involved in several innate antimicrobial defenses including type I interferon (IFN) antiviral responses. Promoter-based bioinformatic analyses implicate increased activity of CREB and NF-κB transcription factors and decreased activity of IFN response factors (IRFs) in structuring the observed differences in gene expression. Transcript origin analyses identify monocytes and CD4+T lymphocytes as primary cellular mediators of transcriptional up-regulation and B lymphocytes as major sources of down-regulated genes. These findings show that adverse social conditions can become embedded within the basal transcriptome of primate immune cells within the first 4 mo of life, and they implicate sympathetic nervous system-linked transcription control pathways as candidate mediators of those effects and potential targets for health-protective intervention.
PKCγ participates in food entrainment by regulating BMAL1
Authors: Zhang Luoying , Abraham Diya , Lin Shu-Ting , Oster Henrik , Eichele Gregor , Fu Ying-Hui , Ptáček Louis J.
Published: November 2012

Temporally restricted feeding (RF) can phase reset the circadian clocks in numerous tissues in mammals, contributing to altered timing of behavioral and physiological rhythms. However, little is known regarding the underlying molecular mechanism. Here we demonstrate a role for the gamma isotype of protein kinase C (PKCγ) in food-mediated entrainment of behavior and the molecular clock. We found that daytime RF reduced late-night activity in wild-type mice but not mice homozygous for a null mutation of
PKCγ
(
PKCγ

−/−

). Molecular analysis revealed that PKCγ exhibited RF-induced changes in activation patterns in the cerebral cortex and that RF failed to substantially phase shift the oscillation of clock gene transcripts in the absence of PKCγ. PKCγ exerts effects on the clock, at least in part, by stabilizing the core clock component brain and muscle aryl hydrocarbon receptor nuclear translocator like 1 (BMAL1) and reducing its ubiquitylation in a deubiquitination-dependent manner. Taken together, these results suggest that PKCγ plays a role in food entrainment by regulating BMAL1 stability.
Polymer-attached zanamivir inhibits synergistically both early and late stages of influenza virus infection
Authors: Lee Chia Min , Weight Alisha K. , Haldar Jayanta , Wang Ling , Klibanov Alexander M. , Chen Jianzhu
Published: November 2012

Covalently conjugating multiple copies of the drug zanamivir (ZA; the active ingredient in Relenza) via a flexible linker to poly-
l
-glutamine (PGN) enhances the anti-influenza virus activity by orders of magnitude. In this study, we investigated the mechanisms of this phenomenon. Like ZA itself, the PGN-attached drug (PGN-ZA) binds specifically to viral neuraminidase and inhibits both its enzymatic activity and the release of newly synthesized virions from infected cells. Unlike monomeric ZA, however, PGN-ZA also synergistically inhibits early stages of influenza virus infection, thus contributing to the markedly increased antiviral potency. This inhibition is not caused by a direct virucidal effect, aggregation of viruses, or inhibition of viral attachment to target cells and the subsequent endocytosis; rather, it is a result of interference with intracellular trafficking of the endocytosed viruses and the subsequent virus-endosome fusion. These findings both rationalize the great anti-influenza potency of PGN-ZA and reveal that attaching ZA to a polymeric chain confers a unique mechanism of antiviral action potentially useful for minimizing drug resistance.
Quantitative and qualitative analysis of a set of goal attainment forms in primary care mental health services
Authors: Proctor Gillian , Hargate Rebecca
Published: November 2012

Aims: The aim of this paper is to present an attempt to collate the results of the client‐completed Goal Attainment Form (GAF) and to explore the usefulness of analysing the data in this way. The GAF is used primarily to add qualitative idiosyncratic data to the quantitative data collected by the CORE‐OM (Clinical Outcomes for Routine Evaluation Outcome Measure) questionnaire. Method: A sample of 477 completed GAF were used during short‐term therapy through primary care mental health services to investigate potential correlations in various different aspects between the GAF and the CORE outcome measure (CORE‐OM). The themes from these forms were qualitatively analysed to compare how clients describe their experience of therapy with clinical perspectives. Results: The results reveal several significant correlations. Themes used by clients to describe their problems and benefits of therapy were different from clinicians' perspectives. Discussion and recommendations: Several suggestions and recommendations are offered regarding evaluation, therapy and primary care short‐term therapy services.
Efficiency-optimized monolithic frequency stabilization of high-power diode lasers
Authors: Crump P , Schultz C M , Wenzel H , Erbert G , Tränkle G
Published: November 2012

High-power GaAs-based diode lasers produce optical energy with extremely high efficiencies, but their spectrum is too broad for many applications (4–5 nm with 95% power content). Narrow spectra (<1 nm) can be achieved using monolithically integrated gratings and recent advances in semiconductor technology have largely eliminated the losses associated with this step. However, it remains challenging to develop designs that simultaneously achieve high power, high efficiencies and narrow spectra over a wide operation range. We review here the design choices necessary for optimized performance, using 975 nm broad-area lasers with uniform overgrown distributed feedback (DFB) gratings as a worked example, focusing on the role of the grating coupling strength. The steps necessary to minimize losses in the grating region are also reviewed. In addition, we show that special measures are needed to sustain narrow spectra in broad-area DFB lasers as they can support multiple longitudinal, lateral and vertical modes.
Emission colour-tunable phosphorescent organic light-emitting diodes based on the self-absorption effect and excimer emission
Authors: Wang Jian , Zhang Fujun , Liu Bo , Xu Zheng , Zhang Jian , Wang Yongsheng
Published: November 2012

Two kinds of emission colour-tunable phosphorescent organic light-emitting diodes (PhOLEDs) were realized by changing the Ir(III) bis [2-(4,6-difluorophenyl)-pyridinato-N,C2′] (picolinate) (FIrpic) doping levels in the host polymer poly(9-vinylcarbazole) (PVK) or by adjusting the driving voltage on the devices with neat FIrpic film as the emission layer. The Commission Internationale del'Eclairage (CIE) coordinates of PhOLEDs could be changed from (0.14, 0.37) to (0.29, 0.55) by adjusting the FIrpic doping levels from 0.08 : 1 to 2 : 1 in the host polymer PVK. It is worthwhile to mention that all PhOLEDs with a FIrpic : PVK film as the emission layer show high emission colour stability dependence on the driving voltage. The photoluminescence emission colour tunability of the FIrpic : PVK films was also observed under the same excitation conditions when the FIrpic : PVK doping level was changed, which is very similar to that observed from electroluminescence (EL) emission of PhOLEDs. For devices with a neat FIrpic film as the emission layer, the EL emission colour of the PhOLEDs could be adjusted by the driving voltage. The CIE coordinates of the PhOLEDs could be tuned from (0.31, 0.50) to (0.44, 0.50) along with an increase in driving voltage from 8 to 20 V. The emission colour tunability of the neat FIrpic or FIrpic : PVK films should be attributed to the FIrpic self-absorption effect and the occurrence of a new emission peak at about 530 nm. The emission peak at about 530 nm was proved to be FIrpic excimer emission by investigating this emission intensity dependence on FIrpic doping levels in PVK or photo/electric-excitation density on FIrpic : PVK and neat FIrpic films.
Effects of N2O and O2 addition to nitrogen Townsend dielectric barrier discharges at atmospheric pressure on the absolute ground-state atomic nitrogen density
Authors: Es-sebbar Et , Gherardi N , Massines F
Published: November 2012

Absolute ground-state density of nitrogen atoms N (2p3
4S3/2) in non-equilibrium Townsend dielectric barrier discharges (TDBDs) at atmospheric pressure sustained in N2/N2O and N2/O2 gas mixtures has been measured using Two-photon absorption laser-induced fluorescence (TALIF) spectroscopy. The quantitative measurements have been obtained by TALIF calibration using krypton as a reference gas. We previously reported that the maximum of N (2p3
4S3/2) atom density is around 3 × 1014 cm−3 in pure nitrogen TDBD, and that this maximum depends strongly on the mean energy dissipated in the gas. In the two gas mixtures studied here, results show that the absolute N (2p3
4S3/2) density is strongly affected by the N2O and O2 addition. Indeed, the density still increases exponentially with the energy dissipated in the gas but an increase in N2O and O2 amounts (a few hundreds of ppm) leads to a decrease in nitrogen atom density. No discrepancy in the order of magnitude of N (2p3
4S3/2) density is observed when comparing results obtained in N2/N2O and N2/O2 mixtures. Compared with pure nitrogen, for an energy of ∼90 mJ cm−3, the maximum of N (2p3
4S3/2) density drops by a factor of 3 when 100 ppm of N2O and O2 are added and it reduces by a factor of 5 for 200 ppm, to reach values close to our TALIF detection sensitivity for 400 ppm (1 × 1013 cm−3 at atmospheric pressure).
The role of the field emission effect in direct-current argon discharges for the gaps ranging from 1 to 100 µm
Authors: Radmilović-Radjenović M , Matejčik Š , Klas M , Radjenović B
Published: November 2012

This paper contains results of experimental and simulation studies of the direct-current breakdown voltage curves in argon discharges with parallel-plane electrodes separated from 1 to 100 µm. The negative slope of the Fowler–Nordheim plot indicates that the current flow is due to field-emitted electrons. Based on the breakdown voltage curves, the effective yield has been estimated. The secondary electron emission in microgaps depends primarily on the electric field E rather than reduced electric field E/N, leading directly to the violation of Paschen's law. The obtained results provide better insight into the role of the enhancement of the secondary electron emission due to high electric field generated in microgaps. Due to the lack of experimental data in microgaps, there are only a few values for the effective yield and no value for argon. By fitting presented experimental data, realistic values of the effective yield in microgaps are obtained and used for the calculations of the breakdown voltages representing basic design data of high-voltage equipment.
Birational contractions of \overline{𝑀}_{3,1} and \overline{𝑀}_{4,1}
Authors: Jensen David
Published: November 2012

We study the birational geometry of

M
¯

3
,
1

\overline {M}_{3,1}

and

M
¯

4
,
1

\overline {M}_{4,1}

. In particular, we pose a pointed analogue of the Slope Conjecture and prove it in these low-genus cases. Using variation of GIT, we construct birational contractions of these spaces in which certain divisors of interest – the pointed Brill-Noether divisors – are contracted. As a consequence, we see that these pointed Brill-Noether divisors generate extremal rays of the effective cones for these spaces.
Predicting adverse events during angiotensin receptor blocker treatment in heart failure: results from the HEAAL trial
Authors: Kiernan Michael S. , Wentworth Deborah , Francis Gary , Martinez Felipe A. , Dickstein Kenneth , Komajda Michel , Zannad Faiez , Neaton James D. , Konstam Marvin A.
Published: November 2012

Aims

In patients with heart failure and reduced left ventricular ejection fraction (HFrEF), renin–angiotensin–aldosterone system blockade reduces morbidity and mortality, but comes at an increased risk of adverse events (AEs). We utilized the HEAAL trial data to identify predictors of the most frequent investigator‐reported AEs.

Methods and results

The HEAAL trial investigated the relationship between losartan dose and outcomes in patients with HFrEF. Cox proportional hazards modelling was used to investigate predictors of AEs and their association with subsequent outcomes. In multivariate analyses, kidney impairment, hyperkalaemia, and hypotension were more likely to occur in older patients (P < 0.01 for each), and those taking aldosterone blockers (P < 0.01 for each). Entry levels of creatinine, potassium, and systolic blood pressure were associated with their respective AEs (P < 0.001 for each). Diabetes, baseline haemoglobin, and diuretic use were predictors (P < 0.05) of kidney impairment and hyperkalaemia. Following AEs due to kidney impairment [hazard ratio (HR) 2.19, 95% confidence interval (CI) 1.91–2.50], hyperkalaemia (HR 1.53, 95% CI 1.27–1.85), and hypotension (HR 1.93, 95% CI 1.62–2.29), the risk of death increased compared with patients who did not experience these AEs.

Conclusion

While the risk of severe AEs is low, patients with HFrEF can be identified who are at increased risk during treatment with an angiotensin receptor blocker. AEs are associated with excess mortality, and at‐risk patients should be monitored closely.
On the hadronic γ-ray emission from Tycho's supernova remnant
Authors: Zhang Xiao , Chen Yang , Li Hui , Zhou Xin
Published: November 2012

Hadronic γ-ray emission from supernova remnants (SNRs) is an important tool to test shock acceleration of cosmic-ray protons. Tycho is one of nearly a dozen Galactic SNRs which are suggested to emit hadronic γ-ray emission. Among them, however, it is the only one in which the hadronic emission is proposed to arise from the interaction with a low-density (∼0.3 cm−3) ambient medium. Here we present an alternative hadronic explanation with a modest energy conversion efficiency (of the order of 1 per cent) for this young remnant. With such an efficiency, a normal electron-to-proton ratio (of the order of 10−2) is derived from the radio and X-ray synchrotron spectra, and an average ambient density that is at least one order of magnitude higher is derived from the hadronic γ-ray flux. This result is consistent with the multiband evidence of the presence of a dense medium from the north to the east of the Tycho SNR. The SNR–cloud association, in combination with the H i absorption data, helps to constrain the so-far controversial distance to Tycho and leads to an estimate of 2.5 kpc.
Subgrid modelling for geophysical flows
Authors: Frederiksen Jorgen S. , O'Kane Terence J. , Zidikheri Meelis J.
Published: November 2012

Recently developed closure-based and stochastic model approaches to subgrid-scale modelling of eddy interactions are reviewed. It is shown how statistical dynamical closure models can be used to self-consistently calculate the eddy damping and stochastic backscatter parameters, required in large eddy simulations (LESs), from higher resolution simulations. A closely related direct stochastic modelling scheme that is more generally applicable to complex models is then described and applied to LESs of quasi-geostrophic turbulence of the atmosphere and oceans. The fundamental differences between atmospheric and oceanic LESs, which are related to the difference in the deformation scales in the two classes of flows, are discussed. It is noted that a stochastic approach may be crucial when baroclinic instability is inadequately resolved. Finally, inhomogeneous closure theory is applied to the complex problem of flow over topography; it is shown that it can be used to understand the successes and limitations of currently used heuristic schemes and to provide a basis for further developments in the future.
Nonlinear problems of complex natural systems: Sun and climate dynamics
Authors: Bershadskii A.
Published: November 2012

The universal role of the nonlinear one-third subharmonic resonance mechanism in generation of strong fluctuations in complex natural dynamical systems related to global climate is discussed using wavelet regression detrended data. The role of the oceanic Rossby waves in the year-scale global temperature fluctuations and the nonlinear resonance contribution to the El Niño phenomenon have been discussed in detail. The large fluctuations in the reconstructed temperature on millennial time scales (Antarctic ice core data for the past 400 000 years) are also shown to be dominated by the one-third subharmonic resonance, presumably related to the Earth's precession effect on the energy that the intertropical regions receive from the Sun. The effects of galactic turbulence on the temperature fluctuations are also discussed.
Using stellar scintillation for studies of turbulence in the Earth’s atmosphere
Authors: Sofieva V. F. , Dalaudier F. , Vernin J.
Published: November 2012

Stellar scintillation observed through the Earth's atmosphere is the result of interaction of light waves and the turbulent atmosphere. This review is dedicated to using stellar scintillation measurements for studies of turbulence in the Earth's atmosphere. We present an overview of ground-based, air-borne and satellite stellar scintillation measurements, discuss the approaches to data analyses and give an overview of the main geophysical results. We also discuss the benefits of the scintillation method in studies of the structure of air density irregularities and its limitations.
Fronts in anomalous diffusion–reaction systems
Authors: Volpert V. A. , Nec Y. , Nepomnyashchy A. A.
Published: November 2012

A review of recent developments in the field of front dynamics in anomalous diffusion–reaction systems is presented. Both fronts between stable phases and those propagating into an unstable phase are considered. A number of models of anomalous diffusion with reaction are discussed, including models with Lévy flights, truncated Lévy flights, subdiffusion-limited reactions and models with intertwined subdiffusion and reaction operators.
On efficient simulations of multiscale kinetic transport
Authors: Radtke Gregg A. , Péraud Jean-Philippe M. , Hadjiconstantinou Nicolas G.
Published: November 2012

We discuss a new class of approaches for simulating multiscale kinetic problems, with particular emphasis on applications related to small-scale transport. These approaches are based on a decomposition of the kinetic description into an equilibrium part, which is described deterministically (analytically or numerically), and the remainder, which is described using a particle simulation method. We show that it is possible to derive evolution equations for the two parts from the governing kinetic equation, leading to a decomposition that is dynamically and automatically adaptive, and a multiscale method that seamlessly bridges the two descriptionswithout introducing any approximation. Our discussion pays particular attention to stochastic particle simulation methods that are typically used to simulate kinetic phenomena; in this context, these decomposition approaches can be thought of as control-variate variance-reduction formulations, with the nearby equilibrium serving as the control. Such formulations can provide substantial computational benefits in a broad spectrum of applications because a number of transport processes and phenomena of practical interest correspond to perturbations from nearby equilibrium distributions. In many cases, the computational cost reduction is sufficiently large to enable otherwise intractable simulations.
Elementary models for turbulent diffusion with complex physical features: eddy diffusivity, spectrum and intermittency
Authors: Majda Andrew J. , Gershgorin Boris
Published: November 2012

This paper motivates, develops and reviews elementary models for turbulent tracers with a background mean gradient which, despite their simplicity, have complex statistical features mimicking crucial aspects of laboratory experiments and atmospheric observations. These statistical features include exact formulas for tracer eddy diffusivity which is non-local in space and time, exact formulas and simple numerics for the tracer variance spectrum in a statistical steady state, and the transition to intermittent scalar probability density functions with fat exponential tails as certain variances of the advecting mean velocity are increased while satisfying important physical constraints. The recent use of such simple models with complex statistics as unambiguous test models for central contemporary issues in both climate change science and the real-time filtering of turbulent tracers from sparse noisy observations is highlighted throughout the paper.
Mixing efficiency in natural flows
Authors: Lozovatsky I. D. , Fernando H. J. S.
Published: November 2012

It is argued that the mixing efficiency of naturally occurring stratified shear flows,
γ
=
Rf
/(1−
Rf
), where
Rf
is the flux Richardson number, is dependent on at least two governing parameters: the gradient Richardson number
Ri
and the buoyancy Reynolds number
Re
b
=
ε
/
vN
2
. It is found that, in the range approximately 0.03<
Ri
<0.4, which spans 10
4
<
Re
b
<10
6
, the mixing efficiency obtained via direct measurements of fluxes and property gradients in the stable atmospheric boundary layer and homogeneous/stationary balance equations of turbulent kinetic energy (TKE) is nominally similar to that evaluated using the scalar balance equations. Outside these
Ri
and
Re
b
ranges, the commonly used flux-estimation methodology based on homogeneity and stationarity of TKE equations breaks down (e.g. buoyancy effects are unimportant, energy flux divergence is significant or flow is non-stationary). In a wide range, 0.002<
Ri
<1, the mixing efficiency increases with
Ri
, but decreases with
Re
b
. When
Ri
is in the proximity of
Ri
cr
∼0.1–0.25,
γ
can be considered a constant
γ
≈0.16–0.2. The results shed light on the wide variability of
γ
noted in previous studies.
Complex competitive systems and competitive thermodynamics
Authors: Klimenko A. Y.
Published: November 2012

This publication reviews the framework of abstract competition, which is aimed at studying complex systems with competition in their generic form. Although the concept of abstract competition has been derived from a specific field—modelling of mixing in turbulent reacting flows—this concept is, generally, not attached to a specific phenomenon or application. Two classes of competition rules, transitive and intransitive, need to be distinguished. Transitive competitions are shown to be consistent (at least qualitatively) with thermodynamic principles, which allows for introduction of special competitive thermodynamics. Competitive systems can thus be characterized by thermodynamic quantities (such as competitive entropy and competitive potential), which determine that the predominant direction of evolution of the system is directed towards higher competitiveness. There is, however, an important difference: while conventional thermodynamics is constrained by its zeroth law and is fundamentally transitive, the transitivity of competitive thermodynamics depends on the transitivity of the competition rules. The analogy with conventional thermodynamics weakens as competitive systems become more intransitive, while strongly intransitive competitions can display types of behaviour associated with complexity: competitive cooperation and leaping cycles. Results of simulations demonstrating complex behaviour in abstract competitions are presented in the electronic supplementary material.
Bone Mineral Densities and Mechanical Properties of Retrieved Femoral Bone Samples in relation to Bone Mineral Densities Measured in the Respective Patients
Authors: Haba Yvonne , Skripitz Ralf , Lindner Tobias , Köckerling Martin , Fritsche Andreas , Mittelmeier Wolfram , Bader Rainer
Published: November 2012

The bone mineral density (BMD) of retrieved cancellous bone samples is compared to the BMD measuredin vivoin the respective osteoarthritic patients. Furthermore, mechanical properties, in terms of structural modulus (Es) and ultimate compression strength (σmax) of the bone samples, are correlated to BMD data. Human femoral heads were retrieved from 13 osteoarthritic patients undergoing total hip replacement. Subsequently, the BMD of each bone sample was analysed using dual energy X-ray absorptiometry (DXA) as well as ashing. Furthermore, BMDs of the proximal femur were analysed preoperatively in the respective patients by DXA. BMDs of the femoral neck and head showed a wide variation, from1016±166 mg/cm2to1376±404 mg/cm2. BMDs of the bone samples measured by DXA and ashing yielded values of315±199 mg/cm2and347±113 mg/cm3, respectively.Esandσmaxamounted to232±151 N/mm2and6.4±3.7 N/mm2. Significant correlation was found between the DXA and ashing data on the bone samples and the DXA data from the patients at the femoral head (r=0.85and 0.79, resp.).Escorrelated significantly with BMD in the patients and bone samples as well as the ashing data (r=0.79,r=0.82, andr=0.8, resp.).
The Perennial Ryegrass GenomeZipper: Targeted Use of Genome Resources for Comparative Grass Genomics
Authors: Pfeifer Matthias , Martis Mihaela , Asp Torben , Mayer Klaus F.X. , Lübberstedt Thomas , Byrne Stephen , Frei Ursula , Studer Bruno
Published: November 2012

Whole-genome sequences established for model and major crop species constitute a key resource for advanced genomic research. For outbreeding forage and turf grass species like ryegrasses (Lolium spp.), such resources have yet to be developed. Here, we present a model of the perennial ryegrass (Lolium perenne) genome on the basis of conserved synteny to barley (Hordeum vulgare) and the model grass genome Brachypodium (Brachypodium distachyon) as well as rice (Oryza sativa) and sorghum (Sorghum bicolor). A transcriptome-based genetic linkage map of perennial ryegrass served as a scaffold to establish the chromosomal arrangement of syntenic genes from model grass species. This scaffold revealed a high degree of synteny and macrocollinearity and was then utilized to anchor a collection of perennial ryegrass genes in silico to their predicted genome positions. This resulted in the unambiguous assignment of 3,315 out of 8,876 previously unmapped genes to the respective chromosomes. In total, the GenomeZipper incorporates 4,035 conserved grass gene loci, which were used for the first genome-wide sequence divergence analysis between perennial ryegrass, barley, Brachypodium, rice, and sorghum. The perennial ryegrass GenomeZipper is an ordered, information-rich genome scaffold, facilitating map-based cloning and genome assembly in perennial ryegrass and closely related Poaceae species. It also represents a milestone in describing synteny between perennial ryegrass and fully sequenced model grass genomes, thereby increasing our understanding of genome organization and evolution in the most important temperate forage and turf grass species.
L-Leucylglycine 0.67-hydrate and [(4S)-2,2-dimethyl-4-(2-methylpropyl)-5-oxoimidazolidin-3-ium-1-yl]acetate
Authors: Kiyotani Tamiko , Sugawara Yoko
Published: November 2012

Crystals of L-leucylglycine (L-Leu–Gly) 0.67-hydrate, C8H16N2O3·0.67H2O, (I), were obtained from an aqueous solution. There are three symmetrically independent dipeptide zwitterionic molecules in (I) and they are parallel to one another. The hydrogen-bond network composed of carboxylate and amino groups and water molecules extends parallel to theabplane. Hydrophilic regions composed of main chains and hydrophobic regions composed of the isobutyl groups of the leucyl residues are aligned alternately along thecaxis. An imidazolidinone derivative was obtained from L-Leu–Gly and acetone,viz.[(4S)-2,2-dimethyl-4-(2-methylpropyl)-5-oxoimidazolidin-3-ium-1-yl]acetate, C11H20N2O3, (II), and was crystallized from a methanol–acetone solution of L-Leu–Gly. The unit-cell parameters coincide with those reported previously for L-Leu–Gly dihydrate revealing that the previously reported values should be assigned to the structure of (II). One of the imidazolidine N atoms is protonated and the ring is nearly planar, except for the protonated N atom. Protonated N atoms and deprotonated carboxy groups of neighbouring molecules form hydrogen-bonded chains. The ring carbonyl group is not involved in hydrogen bonding.
Australian Art Market Prices During the Global Financial Crisis and Two Earlier Decades
Authors: Higgs Helen
Published: November 2012

This study constructs a quarterly hedonic price index using 64,203 artworks, by seventy‐one well‐known modern and contemporaryAustralian artists, sold at auction houses over the period 1986–2009. The hedonic regression model includes characteristics such as name and living status of the artist, the size and medium of the painting, and the auction house, quarter and year in which the painting was sold. The resulting index indicates that returns onAustralian fine‐art averaged one per cent in nominal terms over the period from quarter 1 1986 to quarter 4 2009 with a standard deviation of seventeen per cent. During the global financial crisis spanning quarter 1 2008 and quarter 4 2009, the average art returns declined in nominal terms by close to six per cent with a standard deviation of twenty‐one per cent. This study also shows that over the entire period the art market only marginally underperformed the stock and housing markets. The low correlations between these markets suggest the benefits of portfolio diversification.
Educational Attainment Across Generations: The Role of Immigration Background*
Authors: COBB‐CLARK DEBORAH A. , NGUYEN TRONG‐HA
Published: November 2012

This paper analyses educational attainment among immigrant and native‐born youth in Australia. We find that young Australians from non‐English‐speaking‐background (NESB) immigrant families have an educational advantage over their English‐speaking‐background (ESB) immigrant and Australian‐born peers. The educational advantages associated with immigrant parents’ higher educational attainment are counterbalanced by the disadvantages associated with immigrant families’ greater socioeconomic disadvantage, making endowment effects overall relatively unimportant in explaining the gap. Instead, most of the educational gap associated with immigration background stems from differences in the educational attainment of immigrant and native‐born youths with the same characteristics. While immigrant parents do not have an enhanced ability to transmit their own educational advantage to their children, they are more effective in shielding their children from some of the negative educational consequences of socioeconomic disadvantage. Finally, immigrant youths’ residential patterns convey substantial educational advantages to them.
Crop biodiversity, productivity and production risk: Panel data micro‐evidence from Ethiopia
Authors: Bangwayo‐Skeete Prosper F. , Bezabih Mintewab , Zikhali Precious
Published: November 2012

This paper uses data from the Central Highlands of Ethiopia to assess the productivity and production risk impacts of crop diversification. Using count index as a measure of crop biodiversity, results show that increasing crop biodiversity contributes positively to farm level productivity. In addition, the findings suggest that the level of production risk significantly responds to the level of diversity, with the effect highly conditional on the skewness. The major contribution of the paper is that, unlike previous similar studies that tended to focus on intra‐crop diversity, it incorporates the mutual interdependencies across crops within a farm by focusing on inter‐crop diversity. Hence the study adds to the growing empirical literature, particularly in Africa, that tests empirical relationships between productivity, risk and crop diversity. An important policy implication for a diversity rich country such as Ethiopia is that agro‐biodiversity can be used to improve agricultural productivity while promoting in situ conservation.
Occurrence and determinants of poor response to short‐term pre‐operative erythropoietin treatment
Authors: van HAELST I. M. M. , EGBERTS A. C. G. , DOODEMAN H. J. , van SOLINGE W. W. , KALKMAN C. J. , BENNIS M. , TRAAST H. S. , van KLEI W. A.
Published: November 2012

Background

This study aimed to explore the occurrence and determinants of poor response to short‐term pre‐operative erythropoietin treatment and the effect of such poor response on transfusion in total hip arthroplasty patients.

Methods

We studied total hip arthroplasty patients who received erythropoietin before surgery. The primary outcome was the pre‐operative increase in haemoglobin (delta haemoglobin) as response to erythropoietin therapy. Additionally, patients were classified in tertiles based on this delta haemoglobin: poor responders (cases), responders and good responders (controls) to erythropoietin. Patient characteristics, comedication and co‐morbidity were collected as potential determinants of erythropoietin response. Regression techniques were used to estimate the strength of the associations and to assess the effect of poor response on transfusion requirement.

Results

A total of 379 patients receiving erythropoietin were eligible to enter the study. Mean delta haemoglobin was 19.3 g/l (standard deviation 9.4). Factors significantly associated with delta haemoglobin were the use of angiotensin II antagonists [−3.1 g/l; 95% confidence interval (CI) −5.7 to −0.6] and vitamin K antagonists (−6.9 g/l; 95% CI −10.0 to −0.2), together with body mass index (BMI) (−0.3 g/l per unit>; 95% CI −0.5 to −0.2). The additional case‐control analysis yielded comparable results. Poor response to erythropoietin was associated with an increased transfusion risk (odds ratio 4.6, 95% CI 2.0–11).

Conclusion

Use of angiotensin II receptor antagonists and vitamin K antagonists, and having a high BMI were determinants of poor response to short‐term pre‐operative erythropoietin treatment in total hip arthroplasty patients. Poor responders had a higher risk for perioperative blood transfusion.