bluuebunny/crossref_metadata_2025 huggingface dataset:
Recurrent twin–twin transfusion syndrome after selective fetoscopic laser photocoagulation: a systematic review of the literature
Authors: Walsh C. A. , McAuliffe F. M.
Published: March 2012

Objectives

Selective fetoscopic laser photocoagulation (SFLP) is now the treatment of choice for twin–twin transfusion syndrome (TTTS). The incidence of recurrent TTTS following SFLP has been inconsistently reported across different studies. We performed a systematic review of TTTS recurrence following SFLP.

Methods

PubMed and MEDLINE online databases were searched for articles published between 2000 and August 2011, using combinations of the terms ‘twin–twin transfusion’, ‘TTTS’, ‘laser’, ‘recur’ and ‘outcome’. Citations identified in the primary search were screened for eligibility. Studies reporting outcomes from selective SFLP for TTTS in twin pregnancies, which addressed specifically the issue of TTTS recurrence, were included. The primary outcome was rate of TTTS recurrence. Secondary outcomes were therapeutic preference and fetal outcomes in cases of recurrent TTTS.

Results

The primary search identified 22 eligible studies that are included in this review (n = 2447 twin pregnancies). Two studies included a minority of non‐selective procedures. The published incidence of recurrent TTTS ranged from 0 to 16%. Clinical management was reported in 65.7% (71/108) cases, with repeat SFLP the most commonly performed secondary intervention. Only three studies provided comprehensive outcome data for cases of recurrent TTTS. The overall rate of neurologically‐intact survival was 44% (23/52). The data were inadequate to determine the effects of secondary therapeutic approach, placental location or gestational age on perinatal outcome in cases of recurrent TTTS.

Conclusions

The published rate of TTTS recurrence following SFLP in monochorionic twin pregnancies ranges from 0 to 16%. Although limited follow‐up data suggest that recurrence is associated with significant perinatal mortality and morbidity, further study is needed. Currently, there are insufficient data available to guide recommendations for clinical management of TTTS recurrence. Future studies on SFLP for TTTS must include details on recurrence rates and provide outcome data specific to the recurrent subset.
The 5′ → 3′ exoribonuclease XRN1/Pacman and its functions in cellular processes and development
Authors: Jones Christopher Iain , Zabolotskaya Maria Vasilyevna , Newbury Sarah Faith
Published: March 2012

XRN1 is a 5′ → 3′ processive exoribonuclease that degrades mRNAs after they have been decapped. It is highly conserved in all eukaryotes, including homologs in Drosophila melanogaster (Pacman), Caenorhabditis elegans (XRN1), and Saccharomyces cerevisiae (Xrn1p). As well as being a key enzyme in RNA turnover, XRN1 is involved in nonsense‐mediated mRNA decay and degradation of mRNAs after they have been targeted by small interfering RNAs or microRNAs. The crystal structure of XRN1 can explain its processivity and also the selectivity of the enzyme for 5′ monophosphorylated RNA. In eukaryotic cells, XRN1 is often found in particles known as processing bodies (P bodies) together with other proteins involved in the 5′ → 3′ degradation pathway, such as DCP2 and the helicase DHH1 (Me31B). Although XRN1 shows little specificity to particular 5′ monophosphorylated RNAs in vitro, mutations in XRN1 in vivo have specific phenotypes suggesting that it specifically degrades a subset of RNAs. In Drosophila, mutations in the gene encoding the XRN1 homolog pacman result in defects in wound healing, epithelial closure and stem cell renewal in testes. We propose a model where specific mRNAs are targeted to XRN1 via specific binding of miRNAs and/or RNA‐binding proteins to instability elements within the RNA. These guide the RNA to the 5′ core degradation apparatus for controlled degradation. WIREs RNA 2012, 3:455–468. doi: 10.1002/wrna.1109

This article is categorized under:

RNA Interactions with Proteins and Other Molecules > RNA–Protein Complexes

RNA Turnover and Surveillance > Regulation of RNA Stability

RNA in Disease and Development > RNA in Disease

RNA in Disease and Development > RNA in Development
Poroplasticity with Cosserat effects
Authors: Chełmiński K. , Neff P. , Owczarek S.
Published: March 2012

We prove existence of solutions to a non‐monotone and non‐gradient type quasi‐static model of poroplasticity with Cosserat effects. It is shown that this model possesses global in time solutions, where the inelastic constitutive equation is satisfied in the sense of Young measures. The methods of proof are a monotone approximation, energy estimates, the fundamental theorem on Young measures, and a passage to the limit with the monotone approximation.
Prognostic Significance of the Metastatic Lymph Node Ratio in Patients with Gastric Cancer
Authors: Lee Sung Ryol , Kim Hyung Ook , Son Byung Ho , Shin Jun Ho , Yoo Chang Hak
Published: March 2012

Background

In gastric cancer, the classification of lymph node status is still a controversial prognostic factor. Recent studies have proposed a new prognostic factor (metastatic lymph node ratio: MLR) for gastric cancer patients who undergo curative resection. The present study tested the hypothesis that MLR was better than the current pN staging system by analyzing the correlation between MLR and the International Union Against Cancer/American Joint Committee on Cancer (UICC/AJCC) staging system, by analyzing the correlation between MLR and 5‐year overall survival (OS), by comparing area under the curve (AUC), and by performing univariate and multivariate analyses for OS.

Methods

Of 409 patients who were diagnosed with gastric adenocarcinoma between January 2003 and December 2006, 370 patients underwent curative resection and were included in this study. The prognostic significance of the number of metastatic lymph nodes and the metastatic lymph node ratio were compared in AUC and univariate and multivariate Cox regression analyses.

Results

MLR was significantly correlated with the depth of invasion and the number of lymph node metastases (p < 0.001). Increasing MLR also was statistically correlated with a lower 5‐year OS rate (p < 0.001). The AUC of MLR and the number of lymph node metastases were not significantly different (p = 0.825). MLR was an independent prognostic factor on multivariate analysis, but the number of metastatic lymph nodes was not.

Conclusions

MLR can be a prognostic factor in patients who undergo radical resection for gastric cancer and can overcome the limitations of existing prognostic factors.
The drag on a flattened bubble moving across a plane substrate
Authors: White L. R. , Carnie S. L.
Published: March 2012

The equilibrium shape of an axisymmetric liquid drop or gas bubble in an immiscible supporting liquid held under gravity against a horizontal plane rigid surface is derived. A thin film of supporting liquid remains between the drop/bubble surface and the rigid substrate at equilibrium, of thickness ${h}_{0} $ determined by the balance of the disjoining pressure $\Pi (h)$ between the drop and the substrate and the internal Laplace pressure of the drop/bubble. The interface is macroscopically flat around the drop axis out to a radius $a$ but matches smoothly into the outer shape of radius $A$ through a boundary layer region of width $a{ H}_{0}^{1/ 2} $ where ${H}_{0} = 2{h}_{0} A/ {a}^{2} $ is a small parameter. The outer drop shape is determined by a balance of buoyancy forces and local Laplace pressure and is roughly spherical if $A/ \lambda \ll 1$, where $\lambda = \sqrt{\gamma / \mrm{\Delta} \rho g} $ is the capillary length in the interface with a logarithmic correction due to the action of the disjoining pressure across the flattened region. With the shape determined, we calculate the drag force on this flattened bubble to lowest order in the velocity as it moves across the rigid substrate using a lubrication approximation valid to terms of $O( \mathop{ ({h}_{0} / a)}\nolimits ^{2} )$ as an integral over the flattened bubble surface of the hydrodynamic pressure. The lubrication theory of itself is not sufficient to determine the drag due to the divergence of that integral if the outer flow field properties are neglected. By using the known exact result for the drag force on an undistorted bubble, the drag on the flattened bubble can be computed as an integral over the lubrication region alone. We derive the drag as a series expansion in the small parameter ${H}_{0} $ by means of a fairly intricate boundary layer analysis. The logarithmic divergence of the translational drag with film thickness ${h}_{0} $ for the undistorted bubble is replaced by the stronger divergence ${ h}_{0}^{\ensuremath{-} 1/ 2} $ to leading order for the flattened bubble case. We present explicit numerical results for the first few terms in the expansion for the case of an exponentially repulsive disjoining pressure, and analytic expressions for these terms in the limit of very short-range disjoining pressure forces. The results of this calculation are compared with recent work (Hodges, Jensen & Rallison, J. Fluid Mech., vol. 512, 2004, p. 95) where disjoining pressure is neglected and hydrodynamic pressure is balanced against buoyancy and Laplace forces. The limits of validity of this linear drag theory are also presented.
Ruminal protozoal contribution to the duodenal flow of fatty acids following feeding of steers on forages differing in chloroplast content
Authors: Huws S. A. , Lee M. R. F. , Kingston-Smith A. H. , Kim E. J. , Scott M. B. , Tweed J. K. S. , Scollan N. D.
Published: March 2012

Ruminant products are criticised for their SFA content relative to PUFA, although n-6:n-3 PUFA is desirable for human health ( < 4). Rumen protozoa are rich in unsaturated fatty acids due to engulfment of PUFA-rich chloroplasts. Increasing the chloroplast content of rumen protozoa offers a potentially novel approach to enhance PUFA flow to the duodenum and subsequent incorporation into meat and milk. We evaluated protozoal contribution to duodenal n-3 PUFA flow due to intracellular chloroplast content. A total of six Holstein × Friesian steers were fed, in a two-period changeover design, either straw:concentrate (S:C, 60:40; DM basis; S:C, low chloroplast) or fresh perennial ryegrass (PRG; high chloroplast). Following 12 d adaptation to diet, ruminal protozoal and whole duodenal samples were obtained. N and fatty acid content of whole duodenum and rumen protozoal samples were assessed and protozoal 18S rDNA quantitative PCR performed, enabling calculation of protozoal N flow. The ratio of individual fatty acids:N in rumen protozoal samples was calculated to obtain protozoal fatty acid flows. Based on total fatty acid flow, contribution (%) of protozoa to individual fatty acid flows was calculated. Protozoal fatty acid data and microscopical observations revealed that protozoa were enriched with 18 : 3n-3 following PRG feeding, compared with the S:C diet, due to increased intracellular chloroplast content. However, duodenal protozoal 18S rDNA concentration post PRG feeding was low, indicating rumen retention of the protozoa. Nutrition influences the 18 : 3n-3 content of protozoa; the challenge is to increase protozoal flow to the small intestine, while maintaining sustainable rumen densities.
Shading after anthesis in wheat influences the amount and relative composition of grain proteins
Authors: CHEN E. , WANG Z. , YIN Y. , GUO J. , CHEN X. , LI Y. , WANG P. , WU G. , NI Y. , CAI T. , YANG W. , CAO L.
Published: March 2012

The high molecular weight glutenin subunits (HMW-GS) and glutenin macropolymer (GMP) in wheat grain are important characteristics that affect the quality of wheat products. Light intensity, as one of the environmental factors affecting grain yield and quality, has been studied extensively; however, little is known about its impact on HMW-GS and distribution of GMP granules in wheat grain. In the present study, two strong-gluten winter wheat cultivars with different subunit compositions were used to evaluate the effect of shading at different grain-filling stages on changes in HMW-GS and distribution of GMP granules in wheat grains. No effects of shading on initial formation time of each individual subunit were found; they responded similarly to shading with an increase in relative content, though the accumulation amount per grain of each individual subunit was decreased due to a decrease in grain weight induced by shading. Shading at different grain-filling stages, especially at the middle grain-filling stage, led to a significant increase in GMP content during grain filling; however, the proportions (by volume, number and surface area) of the larger GMP granules were increased by shading at middle and late grain-filling stages and decreased by shading at early grain-filling stage. It was also found that the content of total HMW-GS was positively correlated with volume proportions of larger GMP granules and negatively correlated with volume proportions of small GMP granules, which indicated that the pattern of response of distribution of GMP granules to shading was closely related to the regulatory effect of shading on the HMW-GS.
Arguing Slavery's Narrative: Southern Regionalists, Ex-slave Autobiographers, and the Contested Literary Representations of the Peculiar Institution, 1824–1849
Authors: SCHERMERHORN CALVIN
Published: March 2012

In the twenty-five years before 1850, southern writers of regional literature and ex-slave autobiographers constructed a narrative of United States slavery that was mutually contradictory and yet mutually influential. That process involved a dynamic hybridization of genres in which authors contested meanings of slavery, arriving at opposing conclusions. They nevertheless focussed on family and the South's distinctive culture. This article explores the dialectic of that argument and contends that white regionalists created a plantation-paternalist romance to which African American ex-slaves responded with depictions of slavery's cruelty and immorality. However, by the 1840s, ex-slaves had domesticated their narratives in part to sell their works in a literary marketplace in which their adversaries’ sentimental fiction sold well. Scholars have not examined white southern literature and ex-slave autobiography in comparative context, and this article shows how both labored to construct a peculiar institution in readers’ imagination. Southern regionalists supplied the elements of a pro-slavery argument and ex-slave autobiographers infused their narratives with abolitionist rhetoric at a time in which stories Americans told about themselves became increasingly important in the national political crisis over slavery extension and fugitive slaves. It was on that discursive ground that the debates of the 1850s were carried forth.
Licensing by modification: The case of Frenchdenominals
Authors: MATHIEU ÉRIC
Published: March 2012

The aim of this paper is to provide an analysis of the positive effect that modification has on the distribution of noun phrases in otherwise illicit environments. I focus ondenominals in French. By focusing on these nominals, whose distribution is altered by the addition of modifiers, the paper shows that modifiers can do much more than simply modify: they can change the syntactic and semantic status of a noun phrase. The licensing property of modifiers is an intriguing topic and has not been greatly discussed in the literature. I argue that modifiers can come to play the role of determiners in French as long as they are accompanied by a headde, which is the spell-out of a Cardinal head (see Lyons 1999). My proposal goes back to an old idea put forward by Damourette & Pichon (1911–1940) according to which, in modified contexts,defunctions as one half of the article while the adjective functions as the other half. More generally, articles in French are seen as dual entities comprising of a specifier and a head. In the absence of the determinerles, an adjective can raise to the specifier of CardinalP. This is achieved via phrasal rather than head movement.
Involvement of calcitonin gene-related peptide and CCL2 production in CD40-mediated behavioral hypersensitivity in a model of neuropathic pain
Authors: Malon Jennifer T. , Maddula Swathi , Bell Harmony , Cao Ling
Published: March 2012

The neuropeptide calcitonin gene-related peptide (CGRP) is known to play a pro-nociceptive role after peripheral nerve injury upon its release from primary afferent neurons in preclinical models of neuropathic pain. We previously demonstrated a critical role for spinal cord microglial CD40 in the development of spinal nerve L5 transection (L5Tx)-induced mechanical hypersensitivity. Herein, we investigated whether CGRP is involved in the CD40-mediated behavioral hypersensitivity. First, L5Tx was found to significantly induce CGRP expression in wild-type (WT) mice up to 14 days post-L5Tx. This increase in CGRP expression was reduced in CD40 knockout (KO) mice at day 14 post-L5Tx. Intrathecal injection of the CGRP antagonist CGRP8–37significantly blocked L5Tx-induced mechanical hypersensitivity.In vitro, CGRP induced glial IL-6 and CCL2 production, and CD40 stimulation added to the effects of CGRP in neonatal glia. Further, there was decreased CCL2 production in CD40 KO mice compared to WT mice 21 days post-L5Tx. However, CGRP8–37did not significantly affect spinal cord CCL2 production following L5Tx in WT mice. Altogether, these data suggest that CD40 contributes to the maintenance of behavioral hypersensitivity following peripheral nerve injury in part through two distinct pathways, the enhancement of CGRP expression and spinal cord CCL2 production.
My Share Is Fair, So I Don’t Care
Authors: Camps Jeroen , Decoster Stijn , Stouten Jeroen
Published: March 2012

In the present research we argue that despite leaders’ self-serving actions, followers can still perceive them as being fair and thus ethical. First, we developed a scale to capture followers’ perceptions of their leaders’ self-serving behavior. Second, in a field study we showed that even though leaders may act self-servingly, if employees perceive their own outcomes as fair (i.e., ethical), they will not see much harm in the leader’s behavior. Finally, in a third study (a scenario study) we replicated the findings of our second study and examined the process underlying the proposed relationships. More specifically, we revealed that people experience increased uncertainty in the face of a self-serving leader and that distributive justice helps them deal with the emotional consequences of these feelings of uncertainty. In sum, our findings indicate that people care less about a self-serving leader as long as their share is fair.
The influence of rifting on escarpment migration on high elevation passive continental margins
Authors: Sacek V. , Braun J. , van der Beek P.
Published: March 2012

Using numerical models that couple surface processes, flexural isostasy, faulting and the thermal effects of rifting, we show that fault‐bounded escarpments created at rift flanks by mechanical unloading and flexural rebound have little potential to “survive” as retreating escarpments if the lower crust under the rift flank is substantially stretched. In this configuration, a drainage divide that persists through time appears landward of the initial escarpment in a position close to a secondary bulge that is created during the rifting event at a distance that depends on the flexural rigidity of the upper crust. Moreover, the migration of the escarpment to the secondary bulge occurs when the pre‐rift topography dips landward, otherwise the evolution of the escarpment is guided by the pre‐existing inland drainage divide. To illustrate this new mechanism for the evolution of passive margins, we study the examples of Southeastern Australia and Southeastern Brazil. We propose that a pre‐existing inland drainage divide with rift related flank uplift can produce the double drainage divide observed in Southeastern Australia. On the other hand, we conclude that it is possible that the Serra do Mar escarpments on the Southeastern Brazilian margin originated as a secondary flexural bulge during rifting that persisted through time. In both cases, the retreating escarpment scenario is unlikely and the present‐day margin morphology can be explained as resulting from rift‐related vertical motions alone, without requiring significant post‐rift “rejuvenation”.
Seismic and aseismic slip pulses driven by thermal pressurization of pore fluid
Authors: Garagash D. I.
Published: March 2012

There are several lines of evidence that suggest that thermal pressurization (TP) of pore fluid within a low‐permeability fault core may play the key role in the development of earthquake slip. To elucidate effects of TP on spontaneous fault slip, we consider solutions for a steadily propagating slip pulse on a fault with a constant sliding friction, the level of which may reflect other thermally‐activated processes at the rupture front (such as the flash heating on asperities). Upon arrival of the pulse front, essentially undrained‐adiabatic TP takes place during the initial slip acceleration from the locked state with a corresponding reduction of the fault strength. With passage of time, the diminishing rate of heating (due to the reduced fault strength) and increasing rate of hydrothermal diffusion from the shear zone offset TP and result in partial recovery of the strength, slip deceleration and eventual locking and healing of the slip. We show that the rupture speedvr decreases with thickness hof the principal shear zone. For lab‐constrained values of fault‐gouge parameters, the TP‐pulse solution predicts seismic (vr∼ km/s) slip on a millimeter‐to‐cm thin principal shear zone; and aseismic slip withvr ∼ 10 km/day and slip rates 1–2 orders above the plate rate on a relatively thick (h∼ 1 m) shear zone. These and other predictions of the TP‐pulse model are consistent with the independent sets of observational constraints for large crustal and subduction interplate earthquakes, and slow slip transients (North Cascadia), respectively. Locking of the slip soon after the diffusive transport of the heat and pore fluid becomes efficient significantly limits the maximum co‐seismic temperature rise to values well below previous theoretical estimates. As a result, the onset of macroscopic melting and some of thermal decomposition reactions, recently suggested to explain strong co‐seismic fault weakening, are precluded over much of the seismogenic zone.
Convergence rate across the Nepal Himalaya and interseismic coupling on the Main Himalayan Thrust: Implications for seismic hazard
Authors: Ader Thomas , Avouac Jean‐Philippe , Liu‐Zeng Jing , Lyon‐Caen Hélène , Bollinger Laurent , Galetzka John , Genrich Jeff , Thomas Marion , Chanard Kristel , Sapkota Soma Nath , Rajaure Sudhir , Shrestha Prithvi , Ding Lin , Flouzat Mireille
Published: March 2012

We document geodetic strain across the Nepal Himalaya using GPS times series from 30 stations in Nepal and southern Tibet, in addition to previously published campaign GPS points and leveling data and determine the pattern of interseismic coupling on the Main Himalayan Thrust fault (MHT). The noise on the daily GPS positions is modeled as a combination of white and colored noise, in order to infer secular velocities at the stations with consistent uncertainties. We then locate the pole of rotation of the Indian plate in the ITRF 2005 reference frame at longitude = − 1.34° ± 3.31°, latitude = 51.4° ± 0.3° with an angular velocity of Ω = 0.5029 ± 0.0072°/Myr. The pattern of coupling on the MHT is computed on a fault dipping 10° to the north and whose strike roughly follows the arcuate shape of the Himalaya. The model indicates that the MHT is locked from the surface to a distance of approximately 100 km down dip, corresponding to a depth of 15 to 20 km. In map view, the transition zone between the locked portion of the MHT and the portion which is creeping at the long term slip rate seems to be at the most a few tens of kilometers wide and coincides with the belt of midcrustal microseismicity underneath the Himalaya. According to a previous study based on thermokinematic modeling of thermochronological and thermobarometric data, this transition seems to happen in a zone where the temperature reaches 350°C. The convergence between India and South Tibet proceeds at a rate of 17.8 ± 0.5 mm/yr in central and eastern Nepal and 20.5 ± 1 mm/yr in western Nepal. The moment deficit due to locking of the MHT in the interseismic period accrues at a rate of 6.6 ± 0.4 × 1019 Nm/yr on the MHT underneath Nepal. For comparison, the moment released by the seismicity over the past 500 years, including 14 MW ≥ 7 earthquakes with moment magnitudes up to 8.5, amounts to only 0.9 × 1019 Nm/yr, indicating a large deficit of seismic slip over that period or very infrequent large slow slip events. No large slow slip event has been observed however over the 20 years covered by geodetic measurements in the Nepal Himalaya. We discuss the magnitude and return period of M > 8 earthquakes required to balance the long term slip budget on the MHT.
Anomalous infrasound propagation in a hot stratosphere and the existence of extremely small shadow zones
Authors: Evers L. G. , van Geyt A. R. J. , Smets P. , Fricke J. T.
Published: March 2012

Long‐range infrasound propagation strongly depends on the state of the stratosphere. Infrasound can be efficiently ducted between the Earth's surface and the stratopause under a favorable wind and temperature structure between 40 and 50 km altitude. Understanding infrasound propagation under variable stratospheric conditions is of importance for a successful verification of the Comprehensive Nuclear‐Test Ban Treaty, in which infrasound is used as a verification technique. Inversely, infrasound observations can be used in acoustic remote sensing of the upper atmosphere. In previous studies, attention has been paid to the strength and direction of the circumpolar vortex wind. In this study, an analysis is made of the temperature effect in the stratosphere on infrasound propagation. A case study is presented from an explosion during a sudden stratospheric warming. During such conditions, the size of the classical stratospheric shadow zone (∼200 km) appeared to be reduced by a factor of 2. The occurrence of such conditions is quantified by evaluating 10 years of atmospheric specifications. It unexpectedly appeared that the size of the shadow zone can become smaller than 100 km, which is confirmed by evaluating infrasound detections from mining blasts in southwestern Siberia, Russia. These results are valid over a latitudinal range of 20°N to 60°N, which is determined by the stratospheric surf zone.
The impact of advective transport by the South Indian Ocean Countercurrent on the Madagascar plankton bloom
Authors: Huhn F. , von Kameke A. , Pérez‐Muñuzuri V. , Olascoaga M. J. , Beron‐Vera F. J.
Published: March 2012

Based on ten years (1998–2007) of satellite ocean color data we analyze the spatiotemporal patterns in the seasonal Madagascar plankton bloom with respect to the advection of the recently discovered Southern Indian Ocean Countercurrent (SICC). In maps of Finite‐time Lyapunov Exponents (FTLE) and Finite‐Time Zonal Drift (FTZD) computed from altimetry derived velocities we observe a narrow zonal jet that starts at ∼25°S at the southern tip of Madagascar, an important upwelling region, and extends to the east further than the largest plankton blooms (∼2500 km). In bloom years, the jet coincides with large parts of the northern boundary of the plankton bloom, acting as a barrier to meridional transport. Our findings suggest that advection is an important and so far underestimated mechanism for the eastward propagation and the extent of the plankton bloom. This supports the hypothesis of a single nutrient source south of Madagascar.
Every cell is sacred
Authors: Jacobs Howy
Published: March 2012

As the US Presidential election campaign gets into gear, Howy peers into a grim future, if current trends should be taken to their (il)logical conclusion
Isoform-selective induction of human p110δ PI3K expression by TNFα: identification of a new and inducible PIK3CD promoter
Authors: Whitehead Maria A. , Bombardieri Michele , Pitzalis Costantino , Vanhaesebroeck Bart
Published: March 2012

PI3Ks (phosphoinositide 3-kinases) are signalling molecules and drug targets with important biological functions, yet the regulation of PI3K gene expression is poorly understood. Key PI3Ks are the class IA PI3Ks that consist of a catalytic subunit (p110α, p110β and p110δ) in complex with a p85 regulatory subunit. Whereas p110α and p110β are ubiquitously expressed, high levels of p110δ are mainly found in white blood cells, with most non-leucocytes expressing low levels of p110δ. In the present paper we report that TNFα (tumour necrosis factor α) stimulation induces p110δ expression in human ECs (endothelial cells) and synovial fibroblasts, but not in leucocytes, through transcription start sites located in a novel promoter region in the p110δ gene (PIK3CD). This promoter is used in all cell types, including solid tumour cell lines that express p110δ, and is activated by TNFα in ECs and synovial fibroblasts. We further present a detailed biochemical and bioinformatic characterization of p110δ gene regulation, demonstrating that PIK3CD has distinct promoters, some of which can be dynamically activated by pro-inflammatory mediators. This is the first molecular identification of a PI3K promoter under the control of acute extracellular stimulation.
Direct elucidation of the effect of building defects on the physical properties of alpha-TmAlB4; An AlB2-type analogous “tiling” compound
Authors: Mori T. , Kuzmych-Ianchuk I. , Yubuta K. , Shishido T. , Okada S. , Kudou K. , Grin Y.
Published: March 2012

With a counterintuitive approach to crystal growth, single crystals of α-TmAlB4 were successfully grown, which were indicated from transmission electron microscopy (TEM) and x-ray diffraction (XRD) measurements and analysis to be virtually free from the ubiquitous building defects, and their properties investigated. Recent developments in rare earth aluminoboride compounds with two-dimensional boron layers have attracted interest due to the heavy fermion superconductivity in β-YbAlB4, multiple anomalies manifesting below the Néel temperatures in α-TmAlB4 attributed to intrinsic building defects, and field stable state in Tm2AlB6. The physical properties of the obtained α-TmAlB4 crystals show a striking difference from the properties of conventional α-TmAlB4 crystals containing building defects. TN = 6.8 K is revealed to be higher than the 5.8 K formerly thought, and the multiple anomalies below TN are replaced by a sharp λ-like peak in the specific heat C. The large effect of the building defects on the physical properties could be directly confirmed, and strikingly it is shown how the large peak structure in the specific heat of the high quality sample could be destroyed by the presence of a small amount (one or two percent) of building defects.
Spin transfer switching characteristics in a [Pd/Co]m/Cu/[Co/Pd]n pseudo spin-valve nanopillar with perpendicular anisotropy
Authors: Thiyagarajah Naganivetha , Lee Kyoung-il , Bae Seongtae
Published: March 2012

We successfully demonstrate spin transfer switching (STS) characteristics in a [Pd/Co]m/Cu/[Co/Pd]n pseudo spin-valve nanopillar with 100 nm diameter. We observed lower critical current density and high giant magnetoresistance (GMR) ratio in our devices compared to other fully perpendicularly magnetized pseudo spin-valve structures. The devices showed a current-perpendicular-to-plane GMR of 1.2% and a STS critical current density of JAP-P = −2.6 × 107 A/cm2 and JP-AP = 3.8 × 107 A/cm2. The observed low critical current density is thought to be due to higher spin-transfer efficiency arising from smaller spin orbital scattering, longer spin diffusion length of the thinner Pd, and thinner soft-layer-film thickness and coercivity in the nanopillar devices.
Micromagnetic specifications for recording self-assembled bit-patterned media
Authors: Dong Yan , Wang Yao , Victora R. H.
Published: March 2012

A design including exchange coupled composite (ECC) bits in hexagonal arrays and a multi-pole write head is proposed to meet the requirement of 9.7 × 10−4 bit error rate, 4 nm magnetic fly height, 5% switching field distribution, 5% synchronization error, and 5% jitter error to achieve 2.9 Tbits/in.2 bit-patterned recording. Our head design writes two staggered tracks in a single pass and has maximum perpendicular field gradients of 580 Oe/nm along the down-track direction and 476 Oe/nm along the cross-track direction.
Development of microscopic magnetometer with reflective objective using magneto-optical Kerr effect
Authors: Kondo Y. , Nakamura Y. , Yamakawa K. , Ishio S. , Ariake J.
Published: March 2012

A microscopic magnetometer using magneto-optical Kerr effect (MOKE) was developed to characterize the magnetic properties of hard magnetic nano-structures such as a bit-patterned medium and a magnetoresistive random access memory. Our new type magnetometer has a unique feature that adopts the reflective objective instead of the generally used refractive lens to reduce the unnecessary rotation of polarization axis of the light by the lens with Verdet constant in a magnetic field. A Schwarzschild-type objective consisting of two spherical mirrors was applied as the reflective objective in our magnetometer. The objective was designed specifically for our magnetometer. An actual focusing spot diameter at the sample surface was estimated to be 4.7 μm by the knife-edge measurement. Furthermore, a magnetization curve was measured by MOKE for the Co80Pt20 thin-film line with a width of 75 μm, and demonstrated that our magnetometer can reduce the unnecessary rotation of polarization axis compared with the one measured by the magnetometer with a refractive lens.
Extended frequency analysis of magnetic losses under rotating induction in soft magnetic composites
Authors: de la Barrière O. , Appino C. , Fiorillo F. , Ragusa C. , Lecrivain M. , Rocchino L. , Ben Ahmed H. , Gabsi M. , Mazaleyrat F. , LoBue M.
Published: March 2012

We present novel results on magnetic losses in soft magnetic composites (SMCs) excited with rotating field. Soft composites are very promising in electrical engineering applications, where new topologies of electrical machines with two- and three-dimensional induction loci are increasingly found. An experimental characterization of industrial SMC products has, therefore, been carried out, up to the kilohertz range, under alternating and circular flux loci, making use of a specifically designed and optimized loss measuring setup. The obtained results have been analyzed for all kinds of excitation, according to the loss separation concept, with the emphasis being placed on the relationship between the rotational and the alternating loss components. In particular, it is found that the ratio between the rotational and the alternating losses is, for any given peak induction, independent of frequency.
Shear driven purging of negatively buoyant fluid from trapezoidal depressions and cavities
Authors: Kirkpatrick M. P. , Armfield S. W. , Williamson N.
Published: March 2012

Experimental data and large eddy simulation results are analysed to investigate shear driven entrainment of a negatively buoyant fluid from trapezoidal depressions and cavities. This flow is of relevance to a number of environmentally significant applications including purging of saline pools in rivers and pollutant dispersion in cities and towns situated within topographic depressions. New scaling relations for the entrainment rate are developed based on physical arguments. Our scaling relations are shown to agree well with both experiments and numerical simulations of this flow in trapezoidal cavities with aspect ratios ranging between 7 and 17, entry beach angles between 8° and 33°, and an exit beach angle of 33°. For the numerical simulations, a sub-filter scale turbulence model is used that combines the dynamic mixed model of Zang et al. [“A dynamic mixed subgrid-scale model and its application to recirculating flows,” Phys. Fluids A 5, 3186 (1993)]10.1063/1.858675 with the dynamic localization procedure of Piomelli and Liu [“Large eddy simulation of rotating channel flows using a localized dynamic model,” Phys. Fluids 7, 839 (1995)]10.1063/1.868607 and a buoyancy correction similar to that proposed by Brown et al. [“Large-eddy simulation of stable atmospheric boundary-layers with a revised stochastic subgrid model,” Q. J. R. Meteorol. Soc. 120, 1485 (1994)]10.1002/qj.49712052004 based on data measured in the stable atmospheric boundary layer. Simulations run using this model give significantly closer agreement with the experimental data than simulations run using a version of the dynamic Smagorinsky model with similar modifications. Support for the physical arguments upon which the scaling relations are based is obtained through a statistical analysis of the turbulent flow fields generated by the numerical simulations.
Fast electro-optics of a single self-assembled quantum dot in a charge-tunable device
Authors: Prechtel Jonathan H. , Dalgarno Paul A. , Hadfield Robert H. , McFarlane Jamie , Badolato Antonio , Petroff Pierre M. , Warburton Richard J.
Published: March 2012

The response of a single InGaAs quantum dot, embedded in a miniaturized charge-tunable device, to an applied GHz bandwidth electrical pulse is investigated via its optical response. Quantum-dot response times of 1.0 ± 0.1 ns are characterized via several different measurement techniques, demonstrating GHz-bandwidth electrical control. Furthermore, a novel optical detection technique based on resonant electron-hole pair generation in the hybridization region is used to map fully the voltage pulse experienced by the quantum dot, showing, in this case, a simple exponential rise.
Characterization of the E(0.31) defect introduced in bulk n-Ge by H or He plasma exposure
Authors: Nyamhere C. , Venter A. , Auret F. D. , Coelho S. M. M. , Murape D. M.
Published: March 2012

Bulk antimony (Sb) doped germanium (n-Ge) samples with doping concentrations ranging between 7.0 × 1014 cm−3 and 2.5 × 1015 cm−3 were exposed to a dc-hydrogen or helium plasma. Hydrogen exposure resulted in the introduction of a single prominent defect level at EC −0.31 eV. Exposing similar samples to He plasmas introduced the same electron trap. The trap concentration increased linearly with dopant concentration suggesting that Sb may be a component of this plasma-induced trap. Thermal annealing kinetics studies suggested that this defect anneals out by diffusion.
Dynamic exchange of counterions of polystyrene sulfonate
Authors: Jia Pengxiang , Yang Qingbo , Gong Yongkuan , Zhao Jiang
Published: March 2012

Adopting a cationic fluorescent molecule, rhodamine 6G, as the probe of the counterions of the model anionic polyelectrolyte (sodium polystyrene sulfonate, PSSNa), the diffusion of the counterion probes inside the solution of PSSNa was studied by fluorescence correlation spectroscopy. Two species of the counterion probes with different diffusion coefficient were discovered—the freely diffusing probes and the probes bound to the PSS− chains. The concentration fraction of these two species was found to change with the concentration and molecular weight of PSSNa. The results show that the counterion binding to the PSS− chain is enhanced with the increase of polymer concentration, attributed to the result of the lowered translational entropic penalty at higher polymer concentrations. The counterion binding is also enhanced with the increase of molecular weight, and the origin was attributed to the chain end effect to the counterion distribution. The results indicate the dynamic exchange process between the free counterions and the bound ones, which is further evidenced by the replacement of the bound probes by the elevated salt levels in the solution.
Stochastic self-assembly of incommensurate clusters
Authors: D’Orsogna M. R. , Lakatos G. , Chou T.
Published: March 2012

Nucleation and molecular aggregation are important processes in numerous physical and biological systems. In many applications, these processes often take place in confined spaces, involving a finite number of particles. Analogous to treatments of stochastic chemical reactions, we examine the classic problem of homogeneous nucleation and self-assembly by deriving and analyzing a fully discrete stochastic master equation. We enumerate the highest probability steady states, and derive exact analytical formulae for quenched and equilibrium mean cluster size distributions. Upon comparison with results obtained from the associated mass-action Becker-Döring equations, we find striking differences between the two corresponding equilibrium mean cluster concentrations. These differences depend primarily on the divisibility of the total available mass by the maximum allowed cluster size, and the remainder. When such mass “incommensurability” arises, a single remainder particle can “emulsify” the system by significantly broadening the equilibrium mean cluster size distribution. This discreteness-induced broadening effect is periodic in the total mass of the system but arises even when the system size is asymptotically large, provided the ratio of the total mass to the maximum cluster size is finite. Ironically, classic mass-action equations are fairly accurate in the coarsening regime, before equilibrium is reached, despite the presence of large stochastic fluctuations found via kinetic Monte-Carlo simulations. Our findings define a new scaling regime in which results from classic mass-action theories are qualitatively inaccurate, even in the limit of large total system size.
Optical properties of amorphous high-k LaGdO3 films and its band alignment with Si
Authors: Pavunny S. P. , Thomas R. , Kumar A. , Fachini E. , Katiyar R. S.
Published: March 2012

Optical properties of pulsed laser ablated amorphous high-k LaGdO3 (LGO) thin films on quartz (0001) substrates and its conduction/valance band offset with Si were studied. Complex refractive index and bandgap were extracted from the transmission spectra. An increase in the bandgap with decreasing film thickness was observed. The degree of structural disorder frozen in the network was estimated using Urbach model and found that the amorphousness increased with decreasing thickness. The analysis of refractive index dispersion with wavelength confirmed the single-effective-oscillator model for the direct inter-band transition. The calculated conduction and valance band offset of LGO with silicon were 2.57 ± 0.15 eV and 1.91 ± 0.15 eV, respectively, and are high enough to suppress the electron or hole injection into the conduction and valence band of LGO from the Si substrate, hence, can be of use as new high-k dielectric for the Si based CMOS technology.
AlGaN/GaN high electron mobility transistors with nickel oxide based gates formed by high temperature oxidation
Authors: Lalinský T. , Vanko G. , Vallo M. , Dobročka E. , Rýger I. , Vincze A.
Published: March 2012

We report on the design of gates of AlGaN/GaN high electron mobility transistors (HEMTs) to be predetermined for high temperature applications. In this design, nickel oxide (NiO) gate interfacial layer is formed by high temperature oxidation (T = 500–800 °C, for 1 min) of 15 nm thick Ni gate contact layer to provide a high temperature stable gate interface. AlGaN/GaN HEMTs with thermic NiO gate contact layer show excellent dc performance with higher peak transconductance, larger gate voltage swing, higher linearity, and thermal stability as compared to the reference device based on Ni gate contact layer.
Exciton spin relaxation in In0.53Ga0.47As/AlAs0.56Sb0.44 quantum wells
Authors: Sasayama K. , Nakanishi S. , Yamaguchi R. , Oyanagi Y. , Ushimi T. , Gozu S. , Mozume T. , Tackeuchi A.
Published: March 2012

The spin relaxation process of In0.53Ga0.47As/AlAs0.56Sb0.44 quantum wells is investigated by spin-dependent pump and probe reflectance measurements with a high time resolution of 200 fs. The observed spin relaxation time of 17.5 ps at 20 K indicates high potential for applications to high-speed optical devices. A positive temperature dependence of the spin relaxation time due to the unique band structure is observed at 30–100 K. The spin relaxation is found to be mainly governed by the Bir-Aronov-Pikus process [Sov. Phys. JETP 42, 705 (1976)] below 100 K and by the D’yakonov-Perel’ process above 100 K.
Highly enhanced charge injection in thienoacene-based organic field-effect transistors with chemically doped contact
Authors: Minari Takeo , Darmawan Peter , Liu Chuan , Li Yun , Xu Yong , Tsukagoshi Kazuhito
Published: March 2012

We describe the mechanism of contact resistance reduction and improvement in device performance of organic field-effect transistors by chemical doping at the contact interface. Insertion of iron(III)trichloride into the contact interface significantly reduced the contact resistance from 200 to 8.8 kΩ cm at a gate voltage of −40 V, and a field-effect mobility of 7.0 cm2/V s was achieved in devices based on dioctylbenzothienobenzothiophene. The improved charge injection is attributable to a reduction in the depletion layer thickness at the contact interface and occupation of trap states in the access region due to the generation of charge carriers by contact doping.
Derivation of second-order nonlinear optical conductivity by the projection-diagram method
Authors: Kang Nam Lyong , Choi Sang Don
Published: March 2012

A projection-diagram method is introduced for optical conductivity with lineshape functions, which takes into account the population criterion that the electron and phonon distribution functions are multiplicatively combined along with the energy conservation factors for proper interpretation of emission and absorption of phonons and photons in all the processes of electron transitions. It is further shown that the second order nonlinear optical conductivity of the system of electrons interacting with phonons, obtained using this method, is identical with that derived by using the state dependent projectors and the KC reduction identities [J. Phys. A: Math. Theor. 43, 165203 (2010)]. We expect that this method can reduce the amount of many-body calculation and can be of help in providing physical intuition into solid state quantum dynamics and representing perturbation expressions for such systems.
Gating mechanism of a P2X4 receptor developed from normal mode analysis and molecular dynamics simulations
Authors: Du Juan , Dong Hao , Zhou Huan-Xiang
Published: March 2012

P2X receptors are trimeric ATP-gated cation channels participating in diverse physiological processes. How ATP binding triggers channel opening remains unclear. Here the gating mechanism of a P2X receptor was studied by normal mode analysis and molecular dynamics (MD) simulations. Based on the resting-state crystal structure, a normal mode involving coupled motions of three β-strands (β1, β13, and β14) at the trimeric interface of the ligand-binding ectodomain and the pore-lining helix (TM2) in the transmembrane domain (TMD) was identified. The resulting widening of the fenestrations above the TMD and opening of the transmembrane pore produce known signatures of channel activation. In MD simulations, ATP was initially placed in the putative binding pocket (defined by four charged residues located in β1, β13 and β14) in two opposite orientations, with the adenine either proximal or distal to the TMD. In the proximal orientation, the triphosphate group extends outward to draw in the four charged residues, leading to closure of β13/β14 toward β1. The adenine ring, wedged between β1 and β13, acts as a fulcrum for the β14 lever, turning a modest closure around the triphosphate group into significant opening of the pre-TM2 loop. The motions of these β-strands are similar to those in the putative channel-activation normal mode. In the distal orientation, the ATP stabilizes the trimeric interface and the closure of the pre-TM2 loop, possibly representing desensitization. Our computational studies produced the first complete model, supported by experimental data, for how ATP binding triggers activation of a P2X receptor.