bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical study of persistent current in a nanoring made of a band insulator
Authors: Mošková Antónia , Moško Martin , Tóbik Jaroslav
Published: September 2012

We study theoretically persistent currents in rings made of band insulators with a fully occupied valence band and empty conduction band. We derive an expression for the persistent current in a one‐dimensional (1D) insulating ring with an arbitrary valence band ε(k). Setting for ε(k) the realistic (numerically calculated) valence bands, we estimate persistent currents in the nanorings made of real band insulators like GaAs, Ge, and InAs. Further, we express the persistent current in the insulating 1D ring through the Wannier functions of the constituting infinite 1D crystal. We find these Wannier functions analytically in the LCAO approximation. We obtain fully analytically the persistent current in the insulating ring and we apply the result to a 1D GaAs ring with conduction electrons subjected to a periodic potential emulating the insulating lattice. In general, persistent currents in rings made of band insulators decay with the ring length exponentially due to the exponential decay of the Wannier function tails. In spite of that, the currents of measurable size are found for a suitably chosen nanorings similar to those fabricated recently for coherent nanoelectronics. Finally, to provide insight, our major results are rederived from the so‐called ring Wannier functions.
Investigation of NV centers in diamond nanocrystallites and nanopillars
Authors: Petkov Emil , Popov Cyril , Rendler Torsten , Petkov Christo , Schnabel Florian , Fedder Helmut , Lee Sang‐Yun , Kulisch Wilhelm , Reithmaier Johann Peter , Wrachtrup Jörg
Published: September 2012

Nitrogen‐vacancy (NV) centers were incorporated during hot filament chemical vapor deposition of diamond nanocrystallites and nanocrystalline diamond (NCD) films. From the latter nanopillars with different diameters were prepared applying electron beam lithography and inductively coupled plasma reactive ion etching. The deposition of either single crystallites or closed films was controlled by the nucleation density on the silicon substrates and the process duration. Optical investigations revealed the presence of ensembles of color centers in both nanostructures. An enhancement of the fluorescence emission by an order of magnitude was observed after the structuring of the NCD films.
Application of copulas to improve covariance estimation for partial least squares
Authors: D'Angelo Gina M. , Weissfeld Lisa A.
Published: September 2012

Dimension reduction techniques, such as partial least squares, are useful for computing summary measures and examining relationships in complex settings. Partial least squares requires an estimate of the covariance matrix as a first step in the analysis, making this estimate critical to the results. In addition, the covariance matrix also forms the basis for other techniques in multivariate analysis, such as principal component analysis and independent component analysis. This paper has been motivated by an example from an imaging study in Alzheimer's disease where there is complete separation between Alzheimer's and control subjects for one of the imaging modalities. This separation occurs in one block of variables and does not occur with the second block of variables resulting in inaccurate estimates of the covariance. We propose the use of a copula to obtain estimates of the covariance in this setting, where one set of variables comes from a mixture distribution. Simulation studies show that the proposed estimator is an improvement over the standard estimators of covariance. We illustrate the methods from the motivating example from a study in the area of Alzheimer's disease. Copyright © 2012 John Wiley & Sons, Ltd.
Flexible CoAl LDH@PEDOT Core/Shell Nanoplatelet Array for High‐Performance Energy Storage
Authors: Han Jingbin , Dou Yibo , Zhao Jingwen , Wei Min , Evans David G. , Duan Xue
Published: September 2012

A CoAl‐layered double hydroxide (LDH)@poly(3,4‐ethylenedioxythiophene) (PEDOT) core/shell nanoplatelet array (NPA) is grown on a flexible Ni foil substrate as a high‐performance pseudocapacitor. The LDH@PEDOT core/shell NPA shows a maximum specific capacitance of 649 F/g (based on the total mass) by cyclic voltammetry (scan rate: 2 mV/s) and 672 F/g by galvanostatic discharge (current density: 1 A/g). Furthermore, the hybrid NPA electrode also exhibits excellent rate capability with a specific energy of 39.4 Wh/kg at a current density of 40 A/g, as well as good long‐term cycling stability (92.5% of its original capacitance is retained after 5000 cycles). These performances are superior to those of conventional supercapacitors and LDH NPA without the PEDOT coating. The largely enhanced pseudocapacitor behavior of the LDH@PEDOT NPA electrode is related to the synergistic effect of its individual components: the LDH nanoplatelet core provides abundant energy‐storage capacity, while the highly conductive PEDOT shell and porous architecture facilitate the electron/mass transport in the redox reaction.
Mechanism of the initiation of mRNA decay: role of eRF3 family G proteins
Authors: Hoshino Shin‐ichi
Published: September 2012

mRNA decay is intimately linked to and regulated by translation in eukaryotes. However, it has remained unclear exactly how mRNA decay is linked to translation. Progress has been made in recent years in understanding the molecular mechanisms of the link between translation and mRNA decay. It has become clear that the eRF3 family of GTP‐binding proteins acts as signal transducers that couple translation to mRNA decay and plays pivotal roles in the regulation of gene expression and mRNA quality control. During translation, the translation termination factor eRF3 in complex with eRF1 recognizes the termination codon which appears at the A site of the terminating ribosome. Depending on whether the termination codon is normal (bona fide) or aberrant (premature), deadenylation‐dependent decay or nonsense‐mediated mRNA decay (NMD) occurs. mRNA without termination codons and mRNA with the propensity to cause the ribosome to stall are recognized as aberrant by other members of the eRF3 family during translation, and these translational events cause nonstop mRNA decay (NSD) and no‐go decay (NGD), respectively. In this review, we focus on how mRNA decay is triggered by translational events and summarize the initiation mechanism for the decay of both normal and aberrant mRNAs. WIREs RNA 2012. doi: 10.1002/wrna.1133

This article is categorized under:

Translation > Translation Mechanisms

RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms

RNA Turnover and Surveillance > Regulation of RNA Stability
Treatment for Critical Lower Limb Ischemia in Elderly Patients
Authors: de Leur Kevin , van Zeeland Michiel L. P. , Ho Gwan H. , de Groot Hans G. W. , Veen Eelco J. , van der Laan Lijckle
Published: September 2012

Background

Critical limb ischemia (CLI) has a poor outcome when left untreated. The benefits of revascularization in the very elderly might be limited because of co‐morbidities and short life expectancy. Therefore, optimal management of CLI in the elderly is not straightforward. We analyzed treatment results for elderly patients with CLI (Rutherford 4 or 5/6) in our clinic.

Methods

Hospital charts of all patients >70 years of age diagnosed with Rutherford stage 4–6 peripheral arterial disease between January 2006 and December 2009 were reviewed. We divided patients into two age groups (70–79 and ≥80 years) to compare treatment results. Primary interventions were defined as conservative, endovascular, reconstructive surgery, and amputation. Outcome measures were mortality, reintervention, and major amputation rates.

Results

There were 191 patients [99 (52 %) were women], median age 78.4 years, range 70–98 years. Altogether, 119 (62 %) patients were aged 70–79 years, and 72 (38 %) were ≥80 years. The primary intervention was equally divided over the two age groups (p = 0.21). Trans‐Atlantic Inter‐Society Consensus Document on Management of Peripheral Arterial Disease (TASC II) classifications of aortoiliac lesions were not significantly different regarding intervention (p = 0.62) or age (p = 0.39). TASC II classification of femoropopliteal lesions was significantly different relative to intervention (p < 0.01) but not different between age groups (p = 0.68). Mortality rate after reconstructive surgery was significant higher in the oldest age group (p < 0.01). After conservative treatment, endovascular treatment, or amputation, the mortality rates were not significantly different between the two age groups (respectively, p = 0.06, p = 0.33, p = 0.76). Reintervention rate was 51 % in the 70‐ to 79‐year group compared to 32 % in the ≥80‐year group. After initial treatment, major amputations were performed in 10 % in the 70‐ to 79‐year group compared to 13 % in the ≥80‐year group.

Conclusions

In patients aged ≥80 years, surgical revascularization resulted in a significant higher mortality rate in our clinic, whereas primary conservative, endovascular treatment and amputation resulted in similar mortality in both age groups. When considering surgical revascularization in the very elderly, surgeons should focus on careful patient selection.
Increased Resection Rates and Survival Among Patients Aged 75 Years and Older with Esophageal Cancer: A Dutch Nationwide Population‐Based Study
Authors: Faiz Zohra , Lemmens Valery E. P. P. , Siersema Peter D. , Nieuwenhuijzen Grard A. P. , Wouters Michel W. J. M. , Rozema Tom , Coebergh Jan Willem W. , Wijnhoven Bas P. L.
Published: September 2012

Background

The incidence of esophageal cancer has grown over the recent decades and 30 % of esophageal cancer patients are now 75 years or older at the time of diagnosis. The aim of this study was to evaluate trends in management and survival of patients aged 75 years or older with esophageal cancer.

Methods

In the Netherlands cancer registry, we identified all patients aged 75 years or older who were diagnosed with esophageal cancer between 1989 and 2008. Trends in management and survival were analyzed by time period (1989–2001 vs. 2002–2008), TNM stage, and age (75–79, 80–84, and 85+ years). χ2 testing was used to analyze time trends in treatment, Kaplan–Meier analysis and log‐rank testing to estimate survival, and Cox regression model to calculate hazard ratios for death.

Results

Some 7,253 patients were included in the study. The surgical resection rate increased over the 1989–2008 period from 8.9 to 12.6 % (p = 0.028), especially among patients aged 75–79 years (44.6 vs. 55.4 %, p < 0.001) and patients with TNM stage I disease (12.7 vs. 22.0 %, p < 0.001). The use of definitive chemoradiotherapy (CRT) also increased (0.19 vs. 2.20 %, p < 0.001). Whereas the use of chemotherapy as a single‐modality treatment more than doubled (0.64 vs. 1.54 %, p = 0.004), that of radiotherapy alone decreased (38.1 vs. 31.6 %, p < 0.001). Although median survival time was marginally higher in the 2002–2008 period than in 1989–2001, overall 5 year survival rates remained low at 6 and 5 %, respectively (p < 0.001). Five‐year survival rate after surgery increased from 16 to 30 % (p < 0.001).

Conclusions

In patients of 75 years or older, surgical treatment and use of definitive CRT have increased between 1989 and 2008. Also, an increase in the use of chemotherapy as a single modality was noted. Overall 5 year survival for all cancer patients was stable but remained poor, while survival of patients who underwent esophagectomy improved significantly in the Netherlands since 1989.
Canadian International Polar Year (2007–2008): an introduction
Authors: Kulkarni T. , Watkins J. M. , Nickels S. , Lemmen D. S.
Published: September 2012

Canadian contributions to International Polar Year (IPY) 2007–2008 were designed to improve the understanding of climate change impacts and adaptation and to gain insight into issues surrounding community health and well-being in Canada’s arctic. Fifty-two research projects, involving scientists, northern partners and communities, focused on the arctic atmosphere and climate, cryosphere, oceans, sea ice, marine ecosystems, terrestrial ecosystems, wildlife as well as human health and community well-being. Key research findings on these topics are presented in this special issue of Climatic Change. This introductory paper presents an overview of the international and Canadian IPY programs and a summary of Canadian IPY results, including progress made in data management and capacity building. The legacy of IPY in Canada includes expanded international scientific cooperation, meaningful partnerships with northern communities, and more northern residents with research training.
The role of shelf acetabuloplasty in early and late stages of Perthes disease: A meta-analysis of observational studies
Authors: Kadhim Muayad , Holmes Larry , Bowen J. Richard
Published: September 2012

Purpose

Perthes disease may result in deformity of the proximal femoral epiphysis and incongruity of the hip, and shelf acetabuloplasty has been frequently used for treatment. The aim of this study was to review the published articles about the outcome of shelf acetabuloplasty as a containment or reconstruction–salvage procedure in Perthes disease.

Methods

We utilized the PubMed online database for peer review articles using the following search terms: shelf arthroplasty, acetabuloplasty, and Perthes. To be included in this meta-analysis, we isolated studies on children with Perthes disease who received shelf acetabuloplasty as a treatment, conducted in any geographic location with the Stulberg classification outcome. Twenty articles were identified for a qualitative systematic review. The fixed effect and random effect meta-analysis were performed as appropriate for the summary pool estimate following the heterogeneity test. The meta-analysis was performed on 11 articles in three categories: all articles, articles for shelf arthroplasty in the early stages of Perthes disease, and in the late stages.

Results

Overall, shelf acetabuloplasty provided 84 % good outcome of Stulberg classes I, II, and III. Shelf acetabuloplasty performed in early stages for containment provided good outcome in 85 %, while only 69 % good outcome was achieved when shelf acetabuloplasty was performed in late stages for reconstruction–salvage.

Conclusion

Shelf acetabuloplasty provides a good or fair Stulberg outcome when performed in early Perthes stages (Waldenström stages I and II) as a containment surgery, but less favorable outcomes were observed when shelf surgery was used for reconstructive–salvage purposes in late Perthes disease stages (Waldenström stages III and IV). Caution is advised in performing the shelf procedure in children over 10–11 years of age.
Geochemistry of Mid-Ocean Ridge Mafic intrusives from the Manipur Ophiolitic Complex, Indo-Myanmar Orogenic Belt, NE India
Authors: Singh A. Krishnakanta , Singh N. Ibotombi , Devi L. Debala , Singh R. K. Bikramaditya
Published: September 2012

Mafic intrusives emplaced within the mélange zone of the Manipur Ophiolitic Complex are subalkaline-tholeiitic affinity with Fe-enrichment. Based on the field occurrences, textures-mineralogy and whole-rock compositions, these mafic intrusives can be identified as type-I (gabbro intrusives) and type-II (basalt-dolerite dykes). The type-I resembling enriched-type mid-ocean ridge basalt (E-MORB) shows moderate LREE enrichment (LaN/SmN = 2.5-2.6), slightly enriched MORB normalized HFSE patterns possibly represent melts derived from enriched MORB sub-oceanic mantle sources by small degree of partial melting. The other type-II has normal-type mid-ocean ridge basalt (N-MORB) geochemical features, as it exhibits nearly flat to depleted LREE (LaN/SmN = 1.0-0.6), flat MORB normalized HFSE patterns with slight LREE/HREE depletion (CeN/YbN = 1.37-0.46). It might have been derived from depleted MORB type sub-oceanic mantle source. The MORB signature displayed by these mafic intrusives indicates that they are dismembered fragments of oceanic crust generated at mid-ocean spreading ridge system and support the hypothesis that the Manipur ophiolites was initially formed in the divergent plate margin.
Sun Belt Rising: Regional Population Change and the Decline in Black Residential Segregation, 1970–2009
Authors: Iceland John , Sharp Gregory , Timberlake Jeffrey M.
Published: September 2012

The goal of this study is to examine the extent to which population shifts over the post–Great Migration period and divergent trends in segregation across regions contributed to the overall decline in black segregation in the United States in recent decades. Using data from the 1970 to 2000 decennial censuses and the 2005–2009 American Community Survey (ACS), our analysis indicates that black dissimilarity and isolation declined more in the South and West than in the Northeast and Midwest. Nevertheless, regional population shifts account for only a modest amount (8 % to 12 %) of the decline in black-white segregation over the period and for an even smaller proportion of the decline in black-nonblack segregation, in part because the largest declines in segregation occurred in the West while the region with the largest relative increase in the black population was the South. Using more refined census divisions rather than census regions provided some additional explanatory power (shifts across divisions explained 15 %–16 % of the decline in black-white segregation): divisions with larger gains in their share of the black population tended to have larger declines in black segregation. Overall, although the effect of the regional redistribution of the black population on declines in segregation was significant, of even greater importance were other causes of substantial declines in segregation in a wide array of metropolitan areas across the country, and especially in the West, over the past 40 years.
Your Place or Mine? On the Residence Choice of Young Couples in Norway
Authors: Løken Katrine V. , Lommerud Kjell Erik , Lundberg Shelly
Published: September 2012

Norwegian registry data are used to investigate the location decisions of a full population cohort of young adults as they complete their education, establish separate households, and form their own families. We find that the labor market opportunities and family ties of both partners affect these location choices. Surprisingly, married men live significantly closer to their own parents than do married women, even if they have children, and this difference cannot be explained by differences in observed characteristics. The principal source of excess female distance from parents in this population is the relatively low mobility of men without a college degree, particularly in rural areas. Despite evidence that intergenerational resource flows, such as childcare and eldercare, are particularly important between women and their parents, the family connections of husbands appear to dominate the location decisions of less-educated married couples.
Discrepancies in military middle‐school adolescents' and parents' perceptions of family functioning, social support, anger frequency, and concerns
Authors: Crow Janet R. , Seybold Amanda K.
Published: September 2012

Previous literature suggests that adolescents' and parents' perceptions of family functioning are typically quite disparate and that perceptual discrepancies increase when a family is under stress. During the years of deployments to Iraq and Afghanistan adolescents in military families have faced uniquely stressful circumstances which may exacerbate difficulties commonly experienced during adolescence. For this study 91 middle‐school adolescent–parent dyads from U.S. Army families were surveyed about their perceptions of family functioning, social support, the adolescent's frequency of anger, and the adolescent's concerns. Findings indicated significant differences in parents' and adolescents' matched ratings for all variables except adolescent concerns. Adolescent–parent perceptual discrepancies were greatest for families who had never experienced deployment and during or following the first deployment. The results of this study may be useful to those supporting military families as they develop strategies to help family members understand the others' perceptions and learn to communicate and solve problems despite the differences.
When Maybe is not good enough
Authors: SPIVEY MICHAEL
Published: September 2012

Many variations upon the theme of parser combinators have been proposed, too many to list here, but the main idea is simple: A parser for phrases of type α is a function that takes an input string and produces results (x, rest), where x is a value of type α, and rest is the remainder of the input after the phrase with value x has been consumed. The results are often arranged into a list, because this allows a parser to signal failure with the empty list of results, an unambiguous success with one result, or multiple possibilities with a longer ‘list of successes’.
Evaluation of an FFQ to assess total energy and nutrient intakes in severely obese pregnant women
Authors: Mohd-Shukri Nor A , Bolton Jennifer L , Norman Jane E , Walker Brian R , Reynolds Rebecca M
Published: September 2012

Objective

FFQ are popular instruments for assessing dietary intakes in epidemiological studies but have not been validated for use in severely obese pregnancy. The aim of the present study was to compare nutrient intakes assessed by an FFQ with those obtained from a food diary among severely obese pregnant women.

Design

Comparison of an FFQ containing 170 food items and a food diary for 4 d (three weekdays and one weekend day); absolute agreement was assessed using the paired t test and relative agreement by Pearson/Spearman correlation, cross-classification into tertiles and weighted kappa values.

Setting

Antenatal metabolic clinic for severely obese women.

Subjects

Thirty-one severely obese (BMI at booking ≥40·0 kg/m2) and thirty-two lean control (BMI = 20·0–24·9 kg/m2) pregnant women.

Results

The findings showed that nutrient intakes estimated by the FFQ were significantly higher than those from the food diary; average correlation was 0·32 in obese and 0·43 in lean women. A mean of 48·5 % of obese and 47·3 % of lean women were correctly classified, while 12·9 % (obese) and 10·0 % (lean) were grossly misclassified. Weighted κ values ranged from −0·04 to 0·79 in obese women and from 0·16 to 0·78 in lean women.

Conclusions

Overall, the relative agreement between the FFQ and food diary was lower in the obese group than in the lean group, but was comparable with earlier studies conducted in pregnant women. The validity assessments suggest that the FFQ is a useful tool for ranking severely obese pregnant women according to the levels of their dietary intake.
Satellite observations of banded VLF emissions in conjunction with energy‐banded ions during very large geomagnetic storms
Authors: Colpitts Christopher A. , Cattell Cynthia A. , Kozyra Janet U. , Parrot Michel
Published: September 2012

Frequency‐banded electromagnetic VLF waves up to 2000 Hz are observed concurrently with warm (10 s to 10,000 s of eV) energy‐banded ions in the low latitude auroral and sub‐auroral zones during every large geomagnetic storm encountered by the FAST and DEMETER satellites. The banded ions and waves persist for several FAST or DEMETER orbits, lasting up to 12 h, in both dawn and dusk sectors, in both the northern and southern hemispheres. If the waves are generated at harmonics of the proton gyrofrequency, the inferred source region would be ∼4000 km altitude. Previous investigations have shown that such waves can propagate from this source region to the locations of both spacecraft. An investigation into the growth of waves at harmonics of fci in the inferred source region suggests that these emissions could be generated by ion bands similar to those observed at the same time as the waves. Magnetospheric waves such as these play a role in energy transfer between distinct particle populations and may contribute to ion heating and ion outflow as well as electron energization. All of these phenomena occur during the strongest magnetic storms. The appearance of the banded ions and associated wave activity suggests that there may be distinct changes in the geospace system that characterize large magnetic storms.
Initiative to establish Research Data Alliance moves forward
Authors: Showstack Randy
Published: September 2012

With the amount of scientific data being gathered growing exponentially—due to the increasing number of sensor networks, scientific instruments, computer models, and other tools—there are enormous scientific opportunities but also significant challenges, including how to effectively share research data within and across scientific communities. A 29 August symposium on global scientific data infrastructures, sponsored by the National Academy of Sciences' Board on Research Data and Information (BRDI), addressed this issue while focusing on a new initiative to establish a Research Data Alliance (RDA). The alliance already has received about $3 million in funding from two U.S. agencies—the National Science Foundation (NSF) and the National Institute of Standards and Technology—the Australian government, and the European Union to move forward with funding a handful of nongovernmental structures (NGS) to work on the initiative, according to Alan Blatecky, director of the NSF's Office of Cyberinfrastructure. The initiative—which he said would include a council, plenary, secretariat, NGSs, and working groups—is on a fast track, with the first NGS meeting planned for 2–3 October in Washington, D. C., and the first meeting of the RDA scheduled for March 2013 in Europe.
Curiosity rover LEGO® version could land soon
Authors: Showstack Randy
Published: September 2012

Now that NASA's Curiosity rover has landed on Mars, a smaller LEGO® plastic brick construction version could be landing in toy stores. Less than 2 weeks after Curiosity set down on 5 August, a LEGO® set concept model designed by a mechanical and aerospace engineer who worked on the real rover garnered its 10,000th supporter on the Web site of CUUSOO, a Japanese partner of the LEGO® group. That milestone triggered a company review that began in September 2012 to test the model's “playability, safety, and ft with the LEGO® brand,” according to a congratulatory statement from the company to designer Stephen Pakbaz. Pakbaz told Eos that he has been an avid LEGO® and space exploration fan for most of his life. “For me, creating a LEGO® model of Curiosity using my firsthand knowledge of the rover was inevitable. What I enjoyed most was being able to faithfully replicate and subsequently demonstrate the rocker‐bogie suspension system to friends, family, and coworkers,” he noted, referring to the suspension system that allows the rover to climb over obstacles while keeping its wheels on the ground. Pakbaz, who is currently with Orbital Sciences Corporation, was involved with aspects of the rover while working at the Jet Propulsion Laboratory from 2007 to 2011 as a mechanical engineer.
A‐posteriori analysis of surface energy budget closure to determine missed energy pathways
Authors: Higgins Chad W.
Published: September 2012

The residual of the surface energy budget is represented as the linearized sum of energy losses due to storage, advection and flux underestimation. Individual contributions to the residual can be quantified through constrained multiple linear regression which identifies the site specific processes that are responsible for the lack of energy budget closure. This residual decomposition approach is applied to energy balance data from the Surface Layer Turbulence and Environmental Science Test (SLTEST) site at the Dugway Proving Grounds in the Utah Salt Flats. In this case, energy storage in the soil and underestimation of the soil heat flux accounted for 89% of the residual variance. Underestimation of the sensible and latent heat fluxes had no apparent contribution to the residual, and the contribution of advection to the residual was not statistically significant.
Heliospheric modulation of galactic cosmic rays during grand solar minima: Past and future variations
Authors: Owens M. J. , Usoskin I. , Lockwood M.
Published: September 2012

Galactic cosmic ray flux at Earth is modulated by the heliospheric magnetic field. Heliospheric modulation potential, Φ, during grand solar minima is investigated using an open solar flux (OSF) model with OSF source based on sunspot number, R, and OSF loss on heliospheric current sheet inclination. Changing dominance between source and loss means Φ varies in‐ (anti‐) phase with R during strong (weak) cycles, in agreement with Φ estimates from ice core records of10Be concentration, which are in‐phase during most of the last 300 years, but anti‐phase during the Maunder Minimum. Model results suggest “flat” OSF cycles, such as solar cycle 20 result from OSF source and loss terms temporarily balancing throughout the cycle. Thus even if solar activity continues to decline steadily, the long‐term drop in OSF through SC21 to SC23 may plateau during SC24, though reemerge in SC25 with the inverted phase relation.
The 2012 Ferrara seismic sequence: Regional crustal structure, earthquake sources, and seismic hazard
Authors: Malagnini Luca , Herrmann Robert B. , Munafò Irene , Buttinelli Mauro , Anselmi Mario , Akinci Aybige , Boschi E.
Published: September 2012

Inadequate seismic design codes can be dangerous, particularly when they underestimate the true hazard. In this study we use data from a sequence of moderate‐sized earthquakes in northeast Italy to validate and test a regional wave propagation model which, in turn, is used to understand some weaknesses of the current design spectra. Our velocity model, while regionalized and somewhatad hoc, is consistent with geophysical observations and the local geology. In the 0.02–0.1 Hz band, this model is validated by using it to calculate moment tensor solutions of 20 earthquakes (5.6 ≥ MW ≥ 3.2) in the 2012 Ferrara, Italy, seismic sequence. The seismic spectra observed for the relatively small main shock significantly exceeded the design spectra to be used in the area for critical structures. Observations and synthetics reveal that the ground motions are dominated by long‐duration surface waves, which, apparently, the design codes do not adequately anticipate. In light of our results, the present seismic hazard assessment in the entire Pianura Padana, including the city of Milan, needs to be re‐evaluated.
Particle‐water heat transfer during explosive volcanic eruptions
Authors: Woodcock D. C. , Gilbert J. S. , Lane S. J.
Published: September 2012

Thermal interaction between volcanic particles and water during explosive eruptions has been quantified using a numerical heat transfer model for spherical particles. The model couples intraparticle conduction with heat transfer from the particle surface by boiling water in order to explore heat loss with time for a range of particle diameters. The results are combined with estimates of particle settling times to provide insight into heat removal during eruption from samples of volcanic particles produced by explosive eruption. Heat removal is restricted by resistance to heat transfer from the volcanic particles with intraparticle thermal conduction important for large particles and surface cooling by boiling dominating for small particles. In most cases, volcanic particles approach thermal equilibrium with the surrounding fluid during an explosive eruption. Application of the results to a sample from the Gjálp 1996, Iceland eruption indicates that, relative to 0○C, 70–80% of the heat is transferred from the particles to boiling water during the settling time before burial in the stratigraphic succession. The implication is that, for subglacial explosive eruptions, much of the heat content of the magma is coupled into melting ice extremely rapidly. If all particles of the Gjálp 1996 deposit were cooled to the local boiling point by the end of the eruption then approximately 78% of the initial heat content was removed from the erupting magma during the eruption. This is consistent with calorimetric calculations based on volumes of ice melted during and after the eruption.
Granular pressure at the base of dry flows of angular rock fragments as a function of grain size and flow volume: A relationship from laboratory experiments
Authors: Cagnoli B. , Romano G. P.
Published: September 2012

Experiments are carried out by releasing angular rock fragments down a curved chute and by measuring the basal pressures that are exerted by the granular flows on the basal containing surface (the substrate). The purpose of these experiments is to understand the mechanisms of energy dissipation and interaction with the ground of rock avalanches and dense pyroclastic flows. Our data show that collisions due to particle agitation affect significantly the basal interaction of granular flows. In particular, our experiments reveal that particle agitation per unit of flow mass increases as grain size increases or as flow volume decreases (with all the other features the same). This is so because as grain size increases or as flow volume decreases (with all the other features the same), there are fewer particles in the flows and the agitation due to the interaction with the rough containing boundary surfaces penetrates relatively more inside the flows. The analysis of the experimental data generates a linear relationship between particle agitation (expressed as a dimensionless basal pressure deviation) and a parameter which is directly proportional to the square of grain size and inversely proportional to the cube root of flow volume. This relationship shows the intrinsic ability of the granular flows to dissipate more energy (larger particle agitation per unit of flow mass) or less energy (smaller particle agitation per unit of flow mass) as a function of flow volume and grain size.
Coseismic slip on the southern Cascadia megathrust implied by tsunami deposits in an Oregon lake and earthquake‐triggered marine turbidites
Authors: Witter Robert C. , Zhang Yinglong , Wang Kelin , Goldfinger Chris , Priest George R. , Allan Jonathan C.
Published: September 2012

We test hypothetical tsunami scenarios against a 4,600‐year record of sandy deposits in a southern Oregon coastal lake that offer minimum inundation limits for prehistoric Cascadia tsunamis. Tsunami simulations constrain coseismic slip estimates for the southern Cascadia megathrust and contrast with slip deficits implied by earthquake recurrence intervals from turbidite paleoseismology. We model the tsunamigenic seafloor deformation using a three‐dimensional elastic dislocation model and test three Cascadia earthquake rupture scenarios: slip partitioned to a splay fault; slip distributed symmetrically on the megathrust; and slip skewed seaward. Numerical tsunami simulations use the hydrodynamic finite element model, SELFE, that solves nonlinear shallow‐water wave equations on unstructured grids. Our simulations of the 1700 Cascadia tsunami require >12–13 m of peak slip on the southern Cascadia megathrust offshore southern Oregon. The simulations account for tidal and shoreline variability and must crest the ∼6‐m‐high lake outlet to satisfy geological evidence of inundation. Accumulating this slip deficit requires ≥360–400 years at the plate convergence rate, exceeding the 330‐year span of two earthquake cycles preceding 1700. Predecessors of the 1700 earthquake likely involved >8–9 m of coseismic slip accrued over >260 years. Simple slip budgets constrained by tsunami simulations allow an average of 5.2 m of slip per event for 11 additional earthquakes inferred from the southern Cascadia turbidite record. By comparison, slip deficits inferred from time intervals separating earthquake‐triggered turbidites are poor predictors of coseismic slip because they meet geological constraints for only 4 out of 12 (∼33%) Cascadia tsunamis.
Probabilistic rainfall thresholds for landslide occurrence using a Bayesian approach
Authors: Berti M. , Martina M. L. V. , Franceschini S. , Pignone S. , Simoni A. , Pizziolo M.
Published: September 2012

Various methods have been proposed in the literature to predict the rainfall conditions that are likely to trigger landslides in a given area. Most of these methods, however, only consider the rainfall events that resulted in landslides and provide deterministic thresholds with a single possible output (landslide or no‐landslide) for a given input (rainfall conditions). Such a deterministic view is not always suited to landslides. Slope stability, in fact, is not ruled by rainfall alone and failure conditions are commonly achieved with a combination of numerous relevant factors. When different outputs (landslide or no‐landslide) can be obtained for the same input a probabilistic approach is preferable. In this work we propose a new method for evaluating rainfall thresholds based on Bayesian probability. The method is simple, statistically rigorous, and returns a value of landslide probability (from 0 to 1) for each combination of the selected rainfall variables. The proposed approach was applied to the Emilia‐Romagna Region of Italy taking advantage of the historical landslide archive, which includes more than 4000 events for which the date of occurrence is known with daily accuracy. The results show that landsliding in the study area is strongly related to rainfall event parameters (duration, intensity, total rainfall) while antecedent rainfall seems to be less important. The distribution of landslide probability in the rainfall duration‐intensity shows an abrupt increase at certain duration‐intensity values which indicates a radical change of state of the system and suggests the existence of a real physical threshold.
Map view restoration of Aegean–West Anatolian accretion and extension since the Eocene
Authors: van Hinsbergen Douwe J. J. , Schmid Stefan M.
Published: September 2012

The Aegean region (Greece, western Turkey) is one of the best studied continental extensional provinces. Here, we provide the first detailed kinematic restoration of the Aegean region since 35 Ma. The region consists of stacked upper crustal slices (nappes) that reflect a complex paleogeography. These were decoupled from the subducting African‐Adriatic lithospheric slab. Especially since ∼25 Ma, extensional detachments cut the nappe stack and exhumed its metamorphosed portions in metamorphic core complexes. We reconstruct up to 400 km of trench‐perpendicular (NE‐SW) extension in two stages. From 25 to 15 Ma, the Aegean forearc rotated clockwise relative to the Moesian platform around Euler poles in northern Greece, accommodated by extensional detachments in the north and an inferred transfer fault SE of the Menderes massif. The majority of extension occurred after 15 Ma (up to 290 km) by opposite rotations of the western and eastern parts of the region. Simultaneously, the Aegean region underwent up to 650 km of post‐25 Ma trench‐parallel extension leading to dramatic crustal thinning on Crete. We restore a detachment configuration with the Mid‐Cycladic Lineament representing a detachment that accommodated trench‐parallel extension in the central Aegean region. Finally, we demonstrate that the Sakarya zone and Cretaceous ophiolites of Turkey cannot be traced far into the Aegean region and are likely bounded by a pre‐35 Ma N‐S fault zone. This fault became reactivated since 25 Ma as an extensional detachment located west of Lesbos Island. The paleogeographic units south of the İzmir‐Ankara‐Sava suture, however, can be correlated from Greece to Turkey.
Variable shortening rates in the eastern Himalayan thrust belt, Bhutan: Insights from multiple thermochronologic and geochronologic data sets tied to kinematic reconstructions
Authors: Long Sean P. , McQuarrie Nadine , Tobgay Tobgay , Coutand Isabelle , Cooper Frances J. , Reiners Peter W. , Wartho Jo‐Anne , Hodges Kip V.
Published: September 2012

We present data on the burial, displacement and exhumation history of the Himalayan fold‐thrust belt in eastern Bhutan. These data document the magnitude and timing of displacement of large, discrete structures and highlight temporal variability in shortening rates. Eight new40Ar/39Ar ages from white mica, 32 new zircon (U‐Th)/He ages, 7 new apatite fission track ages, and 1 new U‐Pb zircon (LA‐MC‐ICP‐MS) metamorphic rim growth age are combined with published cooling ages and deformation temperatures, and incremental shortening magnitudes from restorations of two published balanced cross sections, to illustrate the kinematic and temporal development of the Bhutan thrust belt. Integrating these data from ∼23 Ma to the present illustrates rapid horizontal shortening rates (28–35 mm/yr) between 23–20 Ma and 15–10 Ma, separated by more moderate rates (10–23 mm/yr). Shortening rates decrease significantly to 7–10 mm/yr (and possibly as low as 3–4 mm/yr) from 10 to 0 Ma. This decrease is interpreted to represent the onset of strain partitioning in the eastern part of the Himalayan‐Tibetan orogenic system, between shortening in the Bhutan thrust belt, uplift of the Shillong Plateau, and deformation and outward growth of the northern and eastern Tibetan Plateau. Within estimated error, horizontal shortening rates during emplacement of the Main Central thrust sheet and during construction of the upper Lesser Himalayan duplex approached India‐Asia tectonic velocities. Thus, for periods of time between ∼23–20 Ma and ∼15–10 Ma, the Bhutan thrust belt may have absorbed nearly all India‐Asian convergence at this longitude.
Heparin can liberate high molecular weight DNA from secondary necrotic cells
Authors: Barna Gábor , Sebestyén Anna , Dunai Zsuzsanna A. , Csernus Balázs , Mihalik Rudolf
Published: September 2012

The borderline between necrosis and apoptosis is indistinct, but that between types of cell death is important because necrosis may lead to local inflammation, whereas apoptosis usually does not. In certain autoimmune disorders, inhibition of cell death is crucial, since macromolecules released from the dead cells may accelerate the autoimmune processes. We have used various cell death inhibitors to block cell death induced by 4HPR [N‐(4‐hydroxyphenil)‐retinamide] the BL41 and U937 cell lines. VD‐FMK, a general caspase inhibitor, inhibited DNA fragmentation induced by 4HPR, but not PI (propidium iodide) uptake and necrosis. Interestingly heparin, a serine‐protease inhibitor, lowered the PI fluorescence of the dead cell population and increased the sub‐G1 population as measured by flow cytometry. Regarding these changes, we found that heparin failed to increase DNA fragmentation, but merely liberated high molecular mass DNA fragments from dead cells. The exact mechanism is unclear, but heparin during secondary necrosis might enter the cells, bind RNPs (ribonucleoproteins), and pull them out with the attached DNA, where they would be sensitive to enzymatic degradation. Thus, the results suggest that heparin treatment helps in the clearance of cell debris and decreases the immunogenity of secondary necrotic cells.
Asymptotic expansion of the solution of the steady Stokes equation with variable viscosity in a two-dimensional tube structure
Authors: Cardone G. , Fares R. , Panasenko G. P.
Published: September 2012

The Stokes equation with the varying viscosity is considered in a thin tube structure, i.e., in a connected union of thin rectangles with heights of order ɛ < < 1 and with bases of order 1 with smoothened boundary. An asymptotic expansion of the solution is constructed: it contains some Poiseuille type flows in the channels (rectangles) with some boundary layers correctors in the neighborhoods of the bifurcations of the channels. The estimates for the difference of the exact solution and its asymptotic approximation are proved.
Low-frequency Raman scattering from Si/Ge nanocrystals in different matrixes caused by acoustic phonon quantization
Authors: Mankad Venu , Gupta Sanjeev K. , Jha Prafulla K. , Ovsyuk N. N. , Kachurin G. A.
Published: September 2012

Si and Ge nanocrystals (nc-Si and nc-Ge) with average sizes in the range of 6 and 6.3 nm, embedded in SiO2/GeO2 matrix, were fabricated and their acoustic-phonon vibrational properties were investigated using two different approaches by considering the elastic continuum model and fixed boundary condition. The breathing and quadrupolar modes are found in the spectra. The presence of medium significantly affects the phonon peaks and results into the broadening of the modes which is more in the case of elastically similar materials. The phonon line width is found to depend inversely on the size, similar to that reported experimentally. Using first and second-order optical modes, the electron-phonon coupling strengths have been estimated. The result shows that e-p coupling strength is more in the case of elastically dissimilar materials.
Effect of microstructure on the electromagnetic properties of Al18B4O33w/Co and Al18B4O33w/FeCo composite particles
Authors: Jiang J. T. , Zhen L. , Shao W. Z. , Zhou Z. X.
Published: September 2012

The effect of microstructure on electromagnetic properties was investigated in Al18B4O33w/Co and Al18B4O33w/FeCo composite particles. Resistivity (ρ) and saturation magnetization (Ms) were introduced to determine the relationship between microstructure and electromagnetic properties indirectly. The ρ of Co coatings decreased by nine orders of magnitude when annealed in H2, which substantially affected permittivity and permeability. Intense dielectric relaxation occurred in 2 GHz to 18 GHz band, particularly when the ρ was lower than 1.16 × 10−3 Ω·cm, and a strong eddy current effect began to emerge when the ρ decreased to 5 × 10−4 Ω·cm. An unusual increase in the permeability of the Co coatings was identified, and enhanced exchange-coupling interaction was correspondingly revealed, which was assumed to be related to microstructure evolution. The influence of microstructure observed in Al18B4O33w/Co was further found in the Al18B4O33w/CoFe composite particles. This study suggested that the introduction of ρ and Ms was helpful in demonstrating the relationships between microstructure and electromagnetic properties. However, the quantitative characterization of microstructures and the identification of intrinsic electromagnetic parameters should be studied further.
Two-dimensional background field gravity: A Hamilton-Jacobi analysis
Authors: Bertin M. C. , Pimentel B. M. , Valcárcel C. E.
Published: September 2012

We analyse the constraint structure of the background field model for two-dimensional gravity via the Hamilton-Jacobi formalism. This analysis consists in finding the complete set of involutive Hamiltonians that assure the integrability of the system. We then calculate the characteristic equations of the system, also establishing the equivalence between these equations and the field equations.