Late quaternary fluvial incision and aggradation in the Lesser Himalaya, India

Dosseto, Anthony,May, Jan-Hendrik,Choi, Jeong-Heon,Swander, Zachary J.,Fink, David,Korup, Oliver,Hesse, Paul,Singh, Tejpal,Mifsud, Charles,Srivastava, Pradeep Elsevier 2018 Quaternary science reviews Vol.197 No.-

<P><B>Abstract</B></P> <P>Reconstructing how rivers respond to changes in runoff or sediment supply by incising or aggrading has been pivotal in gauging the role of the Indian Summer Monsoon (ISM) as a geomorphic driver in the Himalayas. Here we present new chronological data for fluvial aggradation and incision from the Donga alluvial fan and the upper Alaknanda River, as well as a compilation of previous work. In addition to conventional OSL-SAR (Single-Aliquot Regenerative-Dose) dating method, we have tested and applied pulsed OSL (POSL) dating for quartz samples that include K-rich feldspar inclusions, which is expected to improve the applicability and validity of OSL ages in the Lesser Himalaya. For previously dated deposits, our OSL ages are shown to be systematically older than previously reported ages. These results suggest periods of aggradation in the Alaknanda and Dehradun Valleys mainly between ∼25 and 35 ka. This most likely reflects decreased stream power during periods of weakened monsoon. In addition, in-situ cosmogenic beryllium-10 was used to infer bedrock surface exposure ages, which are interpreted as episodes of active fluvial erosion. Resulting exposure ages span from 3 to 6 ka, suggesting that strath terraces were exposed relatively recently, and incision was dominant through most of the Holocene. In combination, our results support precipitation-driven fluvial dynamics, which regulates the balance between stream power and sediment supply. On a larger spatial scale, however, fluvial dynamics are probably not spatially homogeneous as aggradation could have been taking place in adjacent catchments while incision dominated in the study area.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Himalayan fluvial history is investigated by establishing a chronology of incision and aggradation. </LI> <LI> We dated alluvial fills using POSL and strath terraces with in-situ cosmogenic beryllium-10. </LI> <LI> Aggradation took place between ∼25 and 35 ka, reflecting decreased stream power during periods of weakened monsoon. </LI> <LI> Bedrock exposure ages span from 3 to 6 ka, suggesting that incision was dominant through most of the Holocene. </LI> <LI> Fluvial dynamics is mainly precipitation-driven, which regulates the balance between stream power and sediment supply. </LI> </UL> </P>

Trends in EU-East Asian Trade and Their Implications for Europe's ASEM Programme

Grimwade, Nigel,Mayes, David G. 세종대학교 국제경제연구소 2000 Journal of Economic Integration Vol.15 No.3

This paper uses a combination of empirical models to investigate how much of a problem the removal of barriers on trade between the ASEM countries is likely to pose for adjustment in the EU economies. While existing revealed comparative advantage and the relative height of barriers suggest that much of the increase in imports will fall in industries where the EU has limited exposure much of the remainder is likely to be highly concentrated and hence costly to absorb. However, a continuation of intra-rather inter-industry specialization seems likely which will reduce the expected costs. Effects on the EU are unlikely to be disproportionate as trade is neither disproportionately restricted in total nor by category. increases in export demand from the Asian countries will help offset the costs for the EU as a whole but not necessarily for the particular firms and employees affected by the growth in imports. The recent Asian crises may have slowed growth but the prospects from liberalization for both partners are still likely to be above average compared to expansion of trade in the world as a whole.

A multi-center, randomized, double blinded, placebo-controlled trial of amantadine to stimulate awakening in comatose patients resuscitated from cardiac arrest

Coppler Patrick J.,Gagnon David J.,Flickinger Katharyn L.,Elmer Jonathan,Callaway, Clifton W.,Guyette Francis X.,Doshi Ankur,Steinberg Alexis,Dezfulian Cameron,Moskowitz Ari L.,Donnino Michael,May Ter 대한응급의학회 2024 Clinical and Experimental Emergency Medicine Vol.11 No.2

Objective We hypothesized that the administration of amantadine would increase awakening of comatose patients resuscitated from cardiac arrest. Methods We performed a prospective, randomized, controlled pilot trial, randomizing subjects to amantadine 100 mg twice daily or placebo for up to 7 days. The study drug was administered between 72 and 120 hours after resuscitation and patients with absent N20 cortical responses, early cerebral edema, or ongoing malignant electroencephalography patterns were excluded. Our primary outcome was awakening, defined as following two-step commands, within 28 days of cardiac arrest. Secondary outcomes included length of stay, awakening, time to awakening, and neurologic outcome measured by Cerebral Performance Category at hospital discharge. We compared the proportion of subjects awakening and hospital survival using Fisher exact tests and time to awakening and hospital length of stay using Wilcoxon rank sum tests. Results After 2 years, we stopped the study due to slow enrollment and lapse of funding. We enrolled 14 subjects (12% of goal enrollment), seven in the amantadine group and seven in the placebo group. The proportion of patients who awakened within 28 days after cardiac arrest did not differ between amantadine (n=2, 28.6%) and placebo groups (n=3, 42.9%; P>0.99). There were no differences in secondary outcomes. Study medication was stopped in three subjects (21.4%). Adverse events included a recurrence of seizures (n=2; 14.3%), both of which occurred in the placebo group. Conclusion We could not determine the effect of amantadine on awakening in comatose survivors of cardiac arrest due to small sample size.

An Empirical Re-examination of the Hotelling Valuation Principle

(Frederick W . Bell),(Donald J . Lacombe),(Michael P . Ryan),(David L . May) 한양대학교 경제연구소 2000 JOURNAL OF ECONOMIC RESEARCH Vol.5 No.2

Determining the Dilution Exponent for Entangled 1,4-Polybutadienes Using Blends of Near-Monodisperse Star with Unentangled, Low Molecular Weight Linear Polymers

Hall, Ryan,Kang, Beom-Goo,Lee, Sanghoon,Chang, Taihyun,Venerus, David C.,Hadjichristidis, Nikos,Mays, Jimmy,Larson, Ronald G. American Chemical Society 2019 Macromolecules Vol.52 No.4

<P>We determine experimentally the “dilution exponent” α for entangled polymers from the scaling of terminal crossover frequency with entanglement density from the linear rheology of three 1,4-polybutadiene star polymers that are blended with low-molecular-weight, unentangled linear 1,4-polybutadiene at various star volume fractions, ϕ<SUB><I>s</I></SUB>. Assuming that the rheology of monodisperse stars depends solely on the plateau modulus <I>G</I><SUB><I>N</I></SUB>(ϕ<SUB>s</SUB>) ∝ ϕ<SUB><I>s</I></SUB><SUP>1+α</SUP>, the number of entanglements per chain <I>M</I><SUB><I>e</I></SUB>(ϕ<SUB><I>s</I></SUB>) ∝ ϕ<SUB><I>s</I></SUB><SUP>-α</SUP>, and the tube-segment frictional Rouse time τ<SUB><I>e</I></SUB>(ϕ<SUB><I>s</I></SUB>) ∝ ϕ<SUB><I>s</I></SUB><SUP>-2α</SUP>, we show that only an α = 1 scaling superposes the <I>M</I><SUB><I>e</I></SUB>(ϕ<SUB><I>s</I></SUB>) dependence of the terminal crossover frequency ω<SUB><I>x</I>,<I>t</I></SUB> of the blends with those of pure stars, not α = 4/3. This is the first determination of α for star polymers that does not rely on any particular tube model implementation. We also show that a generalized tube model, the “Hierarchical model”, using the “Das” parameter set with α = 1 reasonably predicts the rheological data of the melts and blends featured in this paper.</P> [FIG OMISSION]</BR>

Assessing the Range of Validity of Current Tube Models through Analysis of a Comprehensive Set of Star-Linear 1,4-Polybutadiene Polymer Blends

Hall, Ryan,Desai, Priyanka S.,Kang, Beom-Goo,Huang, Qifan,Lee, Sanghoon,Chang, Taihyun,Venerus, David C.,Mays, Jimmy,Ntetsikas, Konstantinos,Polymeropoulos, George,Hadjichristidis, Nikos,Larson, Ronal American Chemical Society 2019 Macromolecules Vol.52 No.20

<P>We blend newly synthesized nearly monodisperse four-arm star 1,4-polybutadienes with various well-entangled linear polymers, confirming the conclusions in Desai et al. [<I>Macromolecules</I>201649 (13)49644977] that advanced tube models, namely, the hierarchical 3.0 and branch-on-branch models [Wang, Z.; <I>J. Rheol.</I>201054 (2)223260], fail to predict the linear rheological data when the pure linear polymers have shorter relaxation times, but within 3-4 orders of magnitude of the star polymer. However, when the linear polymer has a longer relaxation time than the star, our new work, surprisingly, finds that non-monotonic dependence of terminal relaxation behavior on composition is both observed experimentally and captured by the models. Combined with previous data from the literature, we present results from over 50 1,4-polybutadiene star-linear blends, suitable for thorough testing of rheological models of entangled polymers.</P> [FIG OMISSION]</BR>

Challenging Tube and Slip-Link Models: Predicting the Linear Rheology of Blends of Well-Characterized Star and Linear 1,4-Polybutadienes

Desai, Priyanka S.,Kang, Beom-Goo,Katzarova, Maria,Hall, Ryan,Huang, Qifan,Lee, Sanghoon,Shivokhin, Maksim,Chang, Taihyun,Venerus, David C.,Mays, Jimmy,Schieber, Jay D.,Larson, Ronald G. American Chemical Society 2016 Macromolecules Vol.49 No.13

<P>We compare predictions of two of the most advanced versions of the tube model, namely the 'Hierarchical model' by Wang et al. [J. Rheol. 2010, 54, 223] and the BoB (branch-on-branch) model by Das et al. [J. Rheol. 2006, SO, 207], against linear viscoelastic G' and G '' data of binary blends of nearly monodisperse 1,4-polybutadiene 4-arm star polymer of arm molar mass 24 000 g/mol with a monodisperse linear 1,4-polybutadiene of molar mass 58 000 g/mol. The star was carefully synthesized and characterized by temperature gradient interaction chromatography and by linear rheology over a wide frequency region through time temperature superposition. We found large failures of both the Hierarchical and BoB models to predict the terminal relaxation behavior of the star/linear blends, despite their success in predicting the rheology of the pure star and pure linear polymers. This failure occurred regardless of the choices made concerning constraint release, such as assuming arm retraction in 'fat' or 'skinny' tubes. Allowing for 'disentanglement relaxation' to cut off the constraint release Rouse process at long times does lead to improved predictions for our blends, but leads to much worse predictions for other star/linear blends described in the literature, especially those of Shivokhin et al. [Macromolecules 2014, 47, 2451]. In addition, our blends and those of Shivokhin et al. were also tested against a coarse-grained slip-link model, the 'clustered fixed slip-link model (CFSM)' of Schieber and co-workers [J. Rheol. 2014, 58, 723], in which several Kuhn steps are clustered together for computational efficiency. The CFSM with only two molecular-weight- and chain-architecture-independent parameters was able to give very good agreement with all experimental data for both of these sets of blends. In light of its success, the CFSM slip-link model may be used to address the constraint release issue more rigorously and potentially help develop improved tube models.</P>