bluuebunny/crossref_metadata_2025 huggingface dataset:
Intramolecular charge‐transfer excitation energies from range‐separated hybrid functionals using the Yukawa potential
Authors: Akinaga Yoshinobu , Ten‐No Seiichiro
Published: March 2009

Valence and intramolecular charge‐transfer excitation energies of middle‐sized molecules are calculated by time‐dependent density functional theory, with the long‐range corrected hybrid functionals employing the recently developed range‐separation schemes using the Yukawa potential. The Yukawa potential allows modest mixings of the Hartree–Fock exchange over a wide range of electron–electron distance. The Yukawa variant of the Coulomb‐attenuated method (CAM) achieves comparable accuracy in using CAM‐B3LYP functional for predicting not only various types excitation energies but also atomization energies, retaining 100% of the exact exchange potential in large interelectron distances. It is demonstrated that the use of the Yukawa potential is advantageous over the conventional range‐separation schemes with the error function. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Low‐lying excited states of 7‐aminocoumarin derivatives: A theoretical study
Authors: Sakata Tetsuya , Kawashima Yukio , Nakano Haruyuki
Published: March 2009

Excited states of three 7‐aminocoumarin derivatives, coumarin 120 (7‐amino‐4‐methylcoumarin), pyrrolyl coumarin 7‐(1H‐pyrrol‐1‐yl)‐4‐methyl‐2H‐1‐benzopyran‐2‐one, and carbazole‐coumarin hybrid 10H‐4‐methyl‐2H‐2‐oxopyrano[5,6‐b]carbazole, have been studied using B3LYP time‐dependent density functional theory (TDDFT). The solvent effect has been taken into account using the polarizable continuum model. The spectra calculated using TDDFT agree well with the experimental absorption spectra. The electronic structures and the solvent effect for the low‐lying singlet excited states have been investigated. The HOMO of the pyrrolyl coumarin is localized on the pyrrolyl ring, while the HOMO in the other 7‐aminocoumarins is delocalized over the entire molecule. This leads to the weak fluorescence of the pyrrolyl coumarins found in experiments. The HOMO and next HOMO in carbazole‐coumarin hybrids have similar orbital energy values, which is not the case in the other 7‐aminocoumarin derivatives. This leads to the additional peaks found in the 30,000–40,000 cm−1 region of the observed absorption spectra, which are specific for carbazole‐coumarin hybrids. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Symmetry breaking in spin‐restricted, open‐shell Hartree–Fock wave functions
Authors: Li Xiangzhu , Paldus Josef
Published: March 2009

Relying on a unitary group approach (UGA) to coupled‐cluster (CC) theory for open‐shell systems we formulate a spin‐free analogue of Thouless' theorem and derive stability conditions for spin‐restricted, open‐shell Hartree–Fock (ROHF) solutions. The formalism is illustrated on the ground states of the oxygen and boron molecules. For the O2 molecule, the broken‐space‐symmetry solution appears already for a slightly stretched OO bond. For the B2 molecule we find a broken‐symmetry solution even at the equilibrium geometry and, in fact, in almost an entire region of intermolecular separations. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
On a manifestly covariant classical mechanics or ruminations on “The Computable Universe” and the role of mathematical physics in solving the natural resource problems of the future
Authors: Nooijen Marcel , Upadhyay Debajyoti
Published: March 2009

We informally discuss a number of puzzling fundamental issues that illustrate one might view the laws of physics as a loosely connected patchwork of different theories, rather than a grand unified scheme, even within the realm of chemistry. One long‐lasting difficulty is the merging of special relativity and quantum mechanics: the many‐body Dirac equation, which is the most satisfactory description of the effects of relativity in chemistry, is not Lorentz invariant. In this article, we address the formulation of a manifestly Lorentz invariant classical mechanics in which each particle is described by individual space and time coordinates, while the system as a whole evolves according to a Hamiltonian dynamics based upon a universal evolution parameter. The physical interpretation of the theoretical framework, or its agreement with experiment, in particular when the transition would be made to a quantum theory in four dimensions, is not clear at present. Our search for an understanding of the physical concepts underlying the covariant mechanics has led to a broader view on the use of mathematical and theoretical physics: it could possibly be at the basis for a “computable physics” in which the laws of physics are redesigned such that they are optimally suited for computer simulations, rather than aim for the accurate description of physical reality. In the final section of the article, it is argued that this may be a fertile way to address some of the natural resource problems the world is likely to face in the future. This article essentially covers much of the material presented by one of the authors (MN) at the Odyssey meeting in Edmonton, June 2008, and we hope reflects some of the stimulating discourse that can ensue when people from different disciplines are brought together to share their thoughts. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Magnebike: A magnetic wheeled robot with high mobility for inspecting complex‐shaped structures
Authors: Tâche Fabien , Fischer Wolfgang , Caprari Gilles , Siegwart Roland , Moser Roland , Mondada Francesco
Published: March 2009

This paper describes the Magnebike robot, a compact robot with two magnetic wheels in a motorbike arrangement, which is intended for inspecting the inner casing of ferromagnetic pipes with complex‐shaped structures. The locomotion concept is based on an adapted magnetic wheel unit integrating two lateral lever arms. These arms allow for slight lifting off the wheel in order to locally decrease the magnetic attraction force when passing concave edges, as well as laterally stabilizing the wheel unit. The robot has the main advantage of being compact (180 × 130 × 220 mm) and mechanically simple: it features only five active degrees of freedom (two driven wheels each equipped with an active lifter stabilizer and one steering unit). The paper presents in detail design and implementation issues that are specific to magnetic wheeled robots. Low‐level control functionalities are addressed because they are necessary to control the active system. The paper also focuses on characterizing and analyzing the implemented robot. The high mobility is shown through experimental results: the robot not only can climb vertical walls and follow circumferential paths inside pipe structures but it is also able to pass complex combinations of 90‐deg convex and concave ferromagnetic obstacles with almost any inclination regarding gravity. It requires only limited space to maneuver because turning on the spot around the rear wheel is possible. This high mobility enables the robot to access any location in the specified environment. Finally the paper analyzes the maximum payload for different types of environment complexities because this is a key feature for climbing robots and provides a security factor about the risk of falling and slipping. © 2009 Wiley Periodicals, Inc.
Ly-1 Antibody Reactive Clone Is an Important Nucleolar Protein for Control of Self-Renewal and Differentiation in Embryonic Stem Cells
Authors: Li Hui , Wang Beibei , Yang Acong , Lu Rui , Wang Weicheng , Zhou Yang , Shi Guilai , Kwon Sung Won , Zhao Yingming , Jin Ying
Published: March 2009

Embryonic stem cells (ESCs) possess the capacity to self-renew and differentiate into all cell types of an organism. It is essential to understand how these properties are controlled for the potential usage of their derivatives in clinical settings and reprogramming of differentiated somatic cells. Although transcriptional factors, such as Oct4, Sox2, and Nanog, have been considered as a part of the core regulatory circuitry, a growing body of evidence suggests that additional factors exist and contribute to the control of ESC self-renewal and differentiation. Here, we report that Ly-1 antibody reactive clone (LYAR), a zinc finger nucleolar protein highly expressed in undifferentiated ESCs, plays a critical role in maintaining ESC identity. Its downregulation significantly reduces the rate of ESC growth and increases their apoptosis. Moreover, reduced expression of LYAR in ESCs impairs their differentiation capacity, failing to rapidly silence pluripotency markers and to activate differentiation genes upon differentiation. Mechanistically, LYAR forms a complex with another nucleolar protein, nucleolin, and prevents its self-cleavage, maintaining a normal steady-state level of nucleolin protein in undifferentiated ESCs. Interestingly, the downregulation of nucleolin is detrimental to the growth of ESCs and increases the rate of apoptosis, similarly to the knockdown of LYAR. Thus, our data emphasize the fact that other genes besides Oct4 and Nanog are uniquely required for ESC self-renewal and differentiation and demonstrate that LYAR functions to control the stability of nucleolin protein, which in turn is essential for maintaining the self-renewal of ESCs.

Disclosure of potential conflicts of interest is found at the end of this article.
Adiponectin levels correlate with the severity of hypertriglyceridaemia in glycogen storage disease Ia
Authors: Bandsma R. H. J. , Smit G. P. A. , Reijngoud D.‐J. , Kuipers F.
Published: March 2009

Glycogen storage disease type Ia (GSD Ia) is characterized by severe hypercholesterolaemia and hypertriglyceridaemia. Little is known about the aetiology of the hyperlipidaemia in GSD Ia. Adipokines play an important regulatory role in lipid metabolism. We investigated whether adipokine concentrations were correlated with the degree of hyperlipidaemia in GSD Ia patients. Six patients with GSD Ia were studied in semi‐fasted conditions. Adiponectin, but not leptin, correlated (r2 = −0.79, p = 0.02) with plasma triglyceride concentrations in the GSD Ia patients. Leptin correlated well with BMI (r2 = 0.59, p < 0.01). However, neither body mass index (BMI) nor homeostasis model assessment (HOMA), as a marker of insulin sensitivity, correlated with triglyceride concentrations. Although a small number of patients were studied, these results indicate that adiponectin concentrations are correlated with the degree of hypertriglyceridaemia in GSD Ia. Pharmacological treatment aimed at increasing adiponectin levels might improve the metabolic status of these patients.
Occupational Segregation by Race and Sex in Brazil, 1989–2001
Authors: King Mary C.
Published: March 2009

Race and sex differentials in labor market outcomes in Brazil appear substantial, phenomena often tied to occupational segregation. This paper presents an array of Duncan indices of dissimilarity to investigate the magnitude and contours of occupational differentiation in Brazil, as well as changes in the recent past, constructed from Pesquisa Nacional por Amostra de Domicilios (PNAD) microdata for 1989 and 2001. Findings include the facts that measurable occupational differentation by sex is over twice as high as that by race and that differentiation on both counts is highest among people 35 and older and outside the Northeastern region. Occupational differentiation by race appears comparable among women and men, but may be higher among women if accurately measured. Racial differentiation grows with education, while sexual segregation declines. Differentiation has declined modestly since 1989 in almost all categories except by race among younger people, men and the most educated.
The Relationship Between Gender and Postconcussion Symptoms After Sport‐Related Mild Traumatic Brain Injury
Authors: Preiss‐Farzanegan Sarah J. , Chapman Benjamin , Wong Tony M. , Wu Joanne , Bazarian Jeffrey J.
Published: March 2009

Objective

The authors sought to define the relationship between gender and postconcussion symptoms (PCSx) at 3 months after sport‐related mild traumatic brain injury (mTBI) and, further, to examine whether age (minors vs. adults), source of PCSx reporting (self‐reported vs. proxy), previous head injury or loss of consciousness, or the sport type in which the mTBI was incurred explain any observed gender differences in PCSx.

Design

Prospective nested cohort study.

Setting

Regional trauma center emergency department.

Patients

A total of 260 patients who presented with sport‐related mTBI, as defined by American Congress of Rehabilitation Medicine criteria, began the study. The participants who lacked litigation concerning the mTBI and had participated in the follow‐up assessment completed the study (n = 215).

Assessment of Risk Factors

Self, proxy, and interviewer report of age, gender, previous head injury or loss of consciousness, and sport in which injury was sustained.

Main Outcome Measurements

Rivermead Post Concussion Symptoms Questionnaire (RPQ).

Results

Adult females are at greater risk for elevated RPQ scores (odds ratio [OR] = 2.89, 95% confidence interval [95% CI] = 1.25‐6.71;P= .013) but not female minors (OR = 0.87, 95% CI = 0.45‐1.71];P= .695), as compared with male subjects. Adjustment for empirically identified confounders in each age group revealed persisting elevated risk for adult females (OR = 2.57, 95% CI = 1.09‐6.08;P= .031), but not minor females (OR = 1.07, 95% CI = 0.52‐2.19,P= .852). The risk associated with female gender in adults could not be explained by characteristics of the sports, such as helmeted versus not, or contact versus no contact, in which women incurred mTBIs. No sport characteristics were associated with increased risk of PCSx after mTBI.

Conclusions

Adult females, but not female minors, are at increased risk for PCSx after sport‐related mTBI as compared with male patients. This increased risk cannot be explained by self‐report, rather than proxy report, of symptoms, previous head injury or loss of consciousness, age, or sport characteristics. Further research is needed to elucidate the processes of age‐differential recovery from mild brain injury in women and on how to most effectively incorporate appropriate follow‐up after emergency department evaluation.
THE OPTIONAL PROTOCOL TO THE CONVENTION AGAINST TORTURE AND THE DETENTION OF REFUGEES
Authors: Edwards Alice
Published: March 2009

The Optional Protocol to the Convention against Torture entered into force on 22 June 2006. It establishes a Sub-Committee for the Prevention of Torture that has authority to visit places of detention and to assess the conditions of that detention as a way to reduce the incidence of torture or cruel, inhuman or degrading treatment or punishment. Additionally, States parties are required to set up complementary national preventive mechanisms. This article explores both how these mechanisms established under the Optional Protocol could operate in the context of the detention of refugees and/or asylum-seekers, which is an increasingly common occurrence in many parts of the world, as well as whether they add value to existing international mechanisms that are already available in this field. It examines the purported applicability of the Optional Protocol to four refugee/asylum situations, namely detention at airports and other border zones; immigration (or administrative) detention, including semi-open (or semi-closed) asylum centres; closed refugee camps; and extraterritorial processing or holding centres. Reviewing definitional, jurisdictional, and practical issues that may impact on the success or otherwise of these new preventive mechanisms, this article concludes by making a number of recommendations to aid their work in the refugee/asylum context.
The place and date of James Weddell's birth
Authors: Verlinden Jozef
Published: March 2009

It has long been suspected that James Weddell was born in Ostend, Belgium. However, no record of his birth was found during earlier searches in the Belgian archives. New searches in the parish registers of Ostend reveal that he was born in that town on 24 August 1787. The Weddell family is recorded in these archives under the name of Waddle, and it was as such that father Waddle signed documents. The parish registers of Ostend are in Latin and James's name was Latinised to Jacobus. The first record of James Weddell thus refers to Jacobus Waddle. In the parish registers are two other documents relating to the Weddell family: the birth of a brother Charles in 1782 and the death of another brother who was also called Jacobus in 1787. Therefore, the family lived in Ostend at least from 1782 to 1787.
ESTIMATING CONTINUOUS-TIME MODELS ON THE BASIS OF DISCRETE DATA VIA AN EXACT DISCRETE ANALOG
Authors: McCrorie J. Roderick
Published: March 2009

This paper offers a perspective on A.R. Bergstrom’s contribution to continuous-time modeling, focusing on his preferred method of estimating the parameters of a structural continuous-time model using an exact discrete-time analog. Some inherent difficulties in this approach are discussed, which help to explain why, in spite of his prescience, the methods around his time were not universally adopted as he had hoped. Even so, it is argued that Bergstrom’s contribution and legacy is secure and retains some relevance today for the analysis of macroeconomic and financial time series.
A SIMPLE EFFICIENT INSTRUMENTAL VARIABLE ESTIMATOR FOR PANEL AR(p) MODELS WHEN BOTHNANDTARE LARGE
Authors: Hayakawa Kazuhiko
Published: March 2009

In this paper, we show that for panel AR(p) models, an instrumental variable (IV) estimator with instruments deviated from past means has the same asymptotic distribution as the infeasible optimal IV estimator when bothNandT, the dimensions of the cross section and time series, are large. If we assume that the errors are normally distributed, the asymptotic variance of the proposed IV estimator is shown to attain the lower bound when bothNandTare large. A simulation study is conducted to assess the estimator.
FUNCTIONAL PEARL. Proof-directed debugging – Corrigendum
Authors: Harper Robert
Published: March 2009

There is a minor error in Section 3 wherein it is stated that ∖acc 0_ _ k loops in_nitely, even if k succeeds on input _.” This statement is not correct, and should be replaced by ∖If k returns false on input cs, then acc 1_ cs k loops in_nitely.”

The author is grateful to Derek Dreyer for pointing out this mistake, and suggesting the above-mentioned correction.
First-class patterns
Authors: JAY BARRY , KESNER DELIA
Published: March 2009

Pure pattern calculus supports pattern-matching functions in which patterns are first-class citizens that can be passed as parameters, evaluated and returned as results. This new expressive power supports two new forms of polymorphism. Path polymorphism allows recursive functions to traverse arbitrary data structures. Pattern polymorphism allows patterns to be treated as parameters which may be collected from various sources or generated from training data. A general framework for pattern calculi is developed. It supports a proof of confluence that is parameterised by the nature of the matching algorithm, suitable for the pure pattern calculus and all other known pattern calculi.
Awareness and the demand for environmental quality: survey evidence on drinking water in urban India
Authors: JALAN JYOTSNA , SOMANATHAN E. , CHAUDHURI SARASWATA
Published: March 2009

The demand for environmental quality is often presumed to be low in developing countries due to poverty. Less attention has been paid to the possibility that lack of awareness about adverse health effects of environmental pollution could also keep the demand low. We use a household survey from urban India to estimate the effects of schooling, exposure to mass media, and other measures of awareness on home water purification. We find that these measures of awareness have statistically significant effects on home purification and, therefore, on willingness to pay. These effects are similar in magnitude to the wealth effects. Average costs of different home purification methods are used to generate partial estimates of willingness to pay for better drinking water quality.
Sudden stratospheric warmings seen in MINOS deep underground muon data
Authors: Osprey S. , Barnett J. , Smith J. , Adamson P. , Andreopoulos C. , Arms K. E. , Armstrong R. , Auty D. J. , Ayres D. S. , Baller B. , Barnes P. D. , Barr G. D. , Barrett W. L. , Becker B. R. , Belias A. , Bernstein R. H. , Bhattacharya D. , Bishai M. , Blake A. , Bock G. J. , Boehm J. , Boehnlein D. J. , Bogert D. , Bower C. , Buckley‐Geer E. , Cavanaugh S. , Chapman J. D. , Cherdack D. , Childress S. , Choudhary B. C. , Cobb J. H. , Coleman S. J. , Culling A. J. , de Jong J. K. , Dierckxsens M. , Diwan M. V. , Dorman M. , Dytman S. A. , Escobar C. O. , Evans J. J. , Falk E. , Feldman G. J. , Frohne M. V. , Gallagher H. R. , Godley A. , Goodman M. C. , Gouffon P. , Gran R. , Grashorn E. W. , Grossman N. , Grzelak K. , Habig A. , Harris D. , Harris P. G. , Hartnell J. , Hatcher R. , Himmel A. , Holin A. , Hylen J. , Irwin G. M. , Ishitsuka M. , Jaffe D. E. , James C. , Jensen D. , Kafka T. , Kasahara S. M. S. , Kim J. J. , Koizumi G. , Kopp S. , Kordosky M. , Koskinen D. J. , Kreymer A. , Kumaratunga S. , Lang K. , Ling J. , Litchfield P. J. , Litchfield R. P. , Loiacono L. , Lucas P. , Ma J. , Mann W. A. , Marshak M. L. , Marshall J. S. , Mayer N. , McGowan A. M. , Meier J. R. , Messier M. D. , Metelko C. J. , Michael D. G. , Miller L. , Miller W. H. , Mishra S. R. , Moore C. D. , Morfin J. G. , Mualem L. , Mufson S. , Musser J. , Naples D. , Nelson J. K. , Newman H. B. , Nichol R. J. , Nicholls T. C. , Ochoa‐Ricoux J. P. , Oliver W. P. , Ospanov R. , Paley J. , Paolone V. , Pavlovic Z. , Pawloski G. , Pearce G. F. , Peck C. W. , Petyt D. A. , Pittam R. , Plunkett R. K. , Rahaman A. , Rameika R. A. , Raufer T. M. , Rebel B. , Reichenbacher J. , Rodrigues P. A. , Rosenfeld C. , Rubin H. A. , Ruddick K. , Sanchez M. C. , Saoulidou N. , Schneps J. , Schreiner P. , Seun S. M. , Shanahan P. , Smart W. , Smith C. , Smith R. , Sousa A. , Speakman B. , Stamoulis P. , Strait M. , Symes P. , Tagg N. , Talaga R. L. , Tavera M. A. , Thomas J. , Thompson J. , Thomson M. A. , Thron J. L. , Tinti G. , Tzanakos G. , Urheim J. , Vahle P. , Viren B. , Watabe M. , Weber A. , Webb R. C. , Wehmann A. , West N. , White C. , Wojcicki S. G. , Wright D. M. , Yang T. , Zhang K. , Zwaska R.
Published: March 2009

The rate of high energy cosmic ray muons as measured underground is shown to be strongly correlated with upper‐air temperatures during short‐term atmospheric (10‐day) events. The effects are seen by correlating data from the MINOS underground detector and temperatures from the European Centre for Medium Range Weather Forecasts during the winter periods from 2003–2007. This effect provides an independent technique for the measurement of meteorological conditions and presents a unique opportunity to measure both short and long‐term changes in this important part of the atmosphere.
Is coastal mean sea level rising faster than the global mean? A comparison between tide gauges and satellite altimetry over 1993–2007
Authors: Prandi Pierre , Cazenave Anny , Becker Mélanie
Published: March 2009

Based on a careful selection of tide gauges records from the Global Sea Level Observing System network, we investigate whether coastal mean sea level is rising faster than the global mean derived from satellite altimetry over the January 1993–December 2007 time span. Over this 15‐year time span, mean coastal rate of sea level rise is found to be +3.3 ± 0.5 mm/yr, in good agreement with the altimetry‐derived rate of +3.4 ± 0.1 mm/yr. Tests indicate that the trends are statistically significant, hence coastal sea level does not rise faster than the global mean. Although trends agree well, tide gauges‐based mean sea level exhibits much larger interannual variability than altimetry‐based global mean. Interannual variability in coastal sea level appears related to the regional variability in sea level rates reported by satellite altimetry. When global mean sea level is considered (as allowed by satellite altimetry coverage), interannual variability is largely smoothed out.
Is the Dipole Anomaly a major driver to record lows in Arctic summer sea ice extent?
Authors: Wang Jia , Zhang Jinlun , Watanabe Eiji , Ikeda Moto , Mizobata Kohei , Walsh John E. , Bai Xuezhi , Wu Bingyi
Published: March 2009

Recent record lows of Arctic summer sea ice extent are found to be triggered by the Arctic atmospheric Dipole Anomaly (DA) pattern. This local, second–leading mode of sea–level pressure (SLP) anomaly in the Arctic produced a strong meridional wind anomaly that drove more sea ice out of the Arctic Ocean from the western to the eastern Arctic into the northern Atlantic during the summers of 1995, 1999, 2002, 2005, and 2007. In the 2007 summer, the DA also enhanced anomalous oceanic heat flux into the Arctic Ocean via Bering Strait, which accelerated bottom and lateral melting of sea ice and amplified the ice–albedo feedback. A coupled ice–ocean model was used to confirm the historical record lows of summer sea ice extent.
Change in CO2 concentration and O2/N2 ratio in ice cores due to molecular diffusion
Authors: Bereiter Bernhard , Schwander Jakob , Lüthi Dieter , Stocker Thomas F.
Published: March 2009

Polar ice cores are unique archives for ancient air. However, a loss of air due to molecular diffusion during storage could affect the composition of the remaining air. We formulate a model with a high spatial resolution (1 mm) calculating the loss of N2, O2 and CO2 in pure clathrate ice in order to determine which layers of an ice core are affected by significant changes in the CO2 concentration and the δ(O2/N2) ratio for storage durations up to 38 years. The results agree with experimental δ(O2/N2) measurements at ice core pieces performed after different storage durations. Additionally, the calculations confirm the importance of the storage temperature and show that the CO2 concentration is less affected than that of δ(O2/N2). Furthermore, guidelines for ice core sample preparation are provided in dependence of storage duration and temperature.
A Holocene record of climate‐driven shifts in coastal carbon sequestration
Authors: Mitra Siddhartha , Zimmerman Andrew R. , Hunsinger Glendon B. , Willard Debra , Dunn Joshua C.
Published: March 2009

A sediment core collected in the mesohaline portion of Chesapeake Bay was found to contain periods of increased delivery of refractory black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs). The BC was most likely produced by biomass combustion during four centennial‐scale dry periods as indicated by the Palmer Drought Severity Index (PDSI), beginning in the late Medieval Warm Period of 1100 CE. In contrast, wetter periods were associated with increased non‐BC organic matter influx into the bay, likely due to greater runoff and associated nutrient delivery. In addition, an overall increase in both BC and non‐BC organic matter deposition during the past millennium may reflect a shift in climate regime. The finding that carbon sequestration in the coastal zone responds to climate fluctuations at both centennial and millennial scales through fire occurrence and nutrient delivery has implications for past and future climate predictions. Drought‐induced fires may lead, on longer timescales, to greater carbon sequestration and, therefore, represent a negative climate feedback.
Characteristics of organic soil in black spruce forests: Implications for the application of land surface and ecosystem models in cold regions
Authors: Yi Shuhua , Manies Kristen , Harden Jennifer , McGuire A. David
Published: March 2009

Soil organic layers (OL) play an important role in land‐atmosphere exchanges of water, energy and carbon in cold environments. The proper implementation of OL in land surface and ecosystem models is important for predicting dynamic responses to climate warming. Based on the analysis of OL samples of black spruce (Picea mariana), we recommend that implementation of OL for cold regions modeling: (1) use three general organic horizon types (live, fibrous, and amorphous) to represent vertical soil heterogeneity; (2) implement dynamics of OL over the course of disturbance, as there are significant differences of OL thickness between young and mature stands; and (3) use two broad drainage classes to characterize spatial heterogeneity, as there are significant differences in OL thickness between dry and wet sites. Implementation of these suggestions into models has the potential to substantially improve how OL dynamics influence variability in surface temperature and soil moisture in cold regions.
A pressure solution creep law for quartz from indentation experiments
Authors: Gratier Jean‐Pierre , Guiguet Robert , Renard François , Jenatton Liliane , Bernard Dominique
Published: March 2009

Indenter experiments have been performed on quartz crystals in order to establish a pressure solution creep law relevant at upper to middle crustal conditions. This deformation mechanism contributes to Earth's crust geodynamics, controlling processes as different as fault permeability, strength, and stress evolution during interseismic periods or mechanochemical differentiation during diagenesis and metamorphism. Indenter experiments have been performed at 350°C and 20–120 MPa during months with differential stress varying from 25 to 350 MPa. Several experimental parameters were varied: nature of quartz (synthetic or natural), nature of fluid, manner in which the solid/solution/solid interface was filled, and orientation of the indented surfaces versus quartz crystallographic c axis. Significant strain rates could only be obtained when using high‐solubility solutions (NaOH 1 mol L−1). Displacement rates of the indenter were found activated by differential stress, with exponential dependence, as theoretically predicted. The mean thickness of the trapped fluid phase below the indenter was estimated in the range 2–10 nm. Moreover, the development of this trapped fluid phase was relatively fast and allowed fluid penetration into previously dry contact regions by marginal dissolution. The indenter displacement rate was driven by differential stress, and its kinetics was controlled by diffusion along the trapped fluid and the development of a morphological roughness along the interface. Conversely, marginal strain energy driven dissolution was observed around the indenter, and its kinetics was controlled by free‐surface reaction. These experimental results are applied to model the interactions between pressure solution and brittle processes in fault zones, providing characteristic time scales for postseismic transitory creep and sealing processes in quartz‐rich rocks.
Effects of the Changjiang (Yangtze) River discharge on planktonic community respiration in the East China Sea
Authors: Chen Chung‐Chi , Shiah Fuh‐Kwo , Chiang Kuo‐Ping , Gong Gwo‐Ching , Kemp W. Michael
Published: March 2009

Planktonic communities tend to flourish on the western margins of the East China Sea (ECS) fueled by substrates delivered largely from the Changjiang River, the fifth largest river in the world. To study the effects of the Changjiang River discharge on planktonic community respiration (CR), physical‐chemical variables and key processes were measured in three consecutive summers in the ECS. Results showed that concentrations of nitrate and Chl a, protozoan biomass, bacterial production, as well as CR in the surface water were all negatively correlated with sea surface salinity, reflecting the strong influence of river discharge on the ECS shelf ecosystem. Moreover, mean values of nitrate, Chl a concentrations, and CR rates were proportionally related to the area of Changjiang diluted water (CDW; salinity ≤31.0 practical salinity units (psu)), an index of river discharge rate. Presumably, higher river flow delivers higher nutrient concentrations which stimulate phytoplankton growth, which in turn fuels CR. CR exhibited significant monthly and interannual variability, and rates appear to be dominated by bacteria and phytoplankton. Although the plankton community was relatively productive (mean = 0.8 mg C m−2 d−1) in the CDW, the mean ratio of production to respiration was low (0.42). This suggests that the heterotrophic processes regulating CR were supported by riverine organic carbon input in addition to in situ autotrophic production.
An overview of aircraft observations from the Pacific Dust Experiment campaign
Authors: Stith J. L. , Ramanathan V. , Cooper W. A. , Roberts G. C. , DeMott P. J. , Carmichael G. , Hatch C. D. , Adhikary B. , Twohy C. H. , Rogers D. C. , Baumgardner D. , Prenni A. J. , Campos T. , Gao RuShan , Anderson J. , Feng Y.
Published: March 2009

Fourteen research flights were conducted in the Pacific Dust Experiment (PACDEX) during April and May 2007 to sample pollution and dust outbreaks from east Asia as they traveled across the northern Pacific Ocean into North America and interacted with maritime storms. Significant concentrations of black carbon (BC, consisting of soot and other light‐absorbing particles measured with a soot photometer 2 instrument) and dust were observed both in the west and east Pacific Ocean from Asian plumes of dust and pollution. BC particles were observed through much of the troposphere, but the major finding is that the percentage of these particles compared with the total number of accumulation mode particles increased significantly (by a factor of 2–4) with increasing altitude, with peak values occurring between 5 and 10 km. Dust plumes had only a small impact on total cloud condensation nuclei at the sampling supersaturations but did exhibit high concentrations of ice nuclei (IN). IN concentrations in dust plumes exceeded typical tropospheric values by 4–20 times and were similar to previous studies in the Saharan aerosol layer when differences in the number concentrations of dust are accounted for. Enhanced IN concentrations were found in the upper troposphere off the coast of North America, providing a first direct validation of the transport of high‐IN‐containing dust layers near the tropopause entering the North American continent from distant sources. A source‐specific chemical transport model was used to predict dust and other aerosols during PACDEX. The model was able to predict several features of the in situ observations, including the general altitudes where BC was found and a peak in the ratio of BC to sulfate between 5 and 10 km.
Effect of changes in relative humidity on aerosol scattering near clouds
Authors: Twohy Cynthia H. , Coakley James A. , Tahnk William R.
Published: March 2009

Many investigations using satellite data have determined that aerosol optical depth and cloud cover are correlated and some have interpreted the correlation as evidence of an aerosol indirect effect on clouds. This study uses in situ aircraft observations taken during the Indian Ocean Experiment (INDOEX), February–March 1999, and mostly over the northern Indian Ocean, to show that on average, relative humidity increases as distance to the boundaries of small marine trade cumulus decreases. The increase is sufficient to cause substantial growth of hygroscopic aerosol particles and consequently greatly enhance particle scattering cross sections near clouds. The measured increase is from a relative humidity of about 90% at 1‐km horizontal distance from the cloud to about 94–96% at 100 m from cloud edge. This increase would result in about a 40–80% increase in aerosol scattering cross section based on the composition used to model the aerosol. Observations of scattering in the vicinity of clouds using 30‐m‐resolution imagery from the Multichannel Cloud Radiometer (MCR) indicated that the increase in scattering within 1–2 km of cloud edge was about 50%, comparable to the increase calculated for the particle scattering cross sections. On the basis of these findings, global average estimates of the aerosol direct radiative effect as derived from satellite observations of cloud‐free oceans is estimated to be 35–65% larger than that inferred for large (>20 km) cloud‐free ocean regions. This enhancement is consistent with those derived from satellite observations.
Plasma environment of Venus: Comparison of Venus Express ASPERA‐4 measurements with 3‐D hybrid simulations
Authors: Martinecz C. , Boesswetter A. , Fränz M. , Roussos E. , Woch J. , Krupp N. , Dubinin E. , Motschmann U. , Wiehle S. , Simon S. , Barabash S. , Lundin R. , Zhang T. L. , Lammer H. , Lichtenegger H. , Kulikov Y.
Published: March 2009

We use data of the ASPERA‐4 ion and electron spectrometers onboard Venus Express to determine the locations and shapes of the plasma boundaries (bow shock, ion composition boundary, and mantle) at Venus. We also investigate the variation of the terminator bow shock position as a function of the solar wind dynamic pressure and solar EUV flux. We compare the results with a 3‐D hybrid simulation. In the hybrid model, ions are treated as individual particles moving in self‐consistently generated electromagnetic fields and electrons are modeled as a massless charge neutralizing fluid. The planetary heavy ion plasma is generated by an oxygen ionosphere and exosphere adapted to a profile, which depends on the solar zenith angle (Chapman layer). A comparison between observations and simulations indicates that the hybrid model is able to produce an adequate picture of the global plasma environment at Venus. The positions of the plasma boundaries are well reproduced by the model but a significant disagreement appears in the absolute values of the considered parameters.
Mathematical modeling and numerical simulation of polythermal glaciers
Authors: Aschwanden A. , Blatter H.
Published: March 2009

A mathematical model for polythermal glaciers and ice sheets is presented. The enthalpy balance equation is solved in cold and temperate ice together using an enthalpy gradient method. To obtain a relationship between enthalpy, temperature, and water content, we apply a brine pocket parameterization scheme known from sea ice modeling. The proposed enthalpy formulation offers two advantages: (1) the discontinuity at the cold‐temperate transition surface is avoided, and (2) no treatment of the transition as an internal free boundary is required. Fourier's law and Fick‐type diffusion are assumed for sensible heat flux in cold ice and latent heat flux in temperate ice, respectively. The method is tested on Storglaciären, northern Sweden. Numerical simulations are carried out with a commercial finite element code. A sensitivity study reveals a wide range of applicability and defines the limits of the method. Realistic temperature and moisture fields are obtained over a large range of parameters.
Technological advances in suspended‐sediment surrogate monitoring
Authors: Gray John R. , Gartner Jeffrey W.
Published: March 2009

Surrogate technologies to continuously monitor suspended sediment show promise toward supplanting traditional data collection methods requiring routine collection and analysis of water samples. Commercially available instruments operating on bulk optic (turbidity), laser optic, pressure difference, and acoustic backscatter principles are evaluated based on cost, reliability, robustness, accuracy, sample volume, susceptibility to biological fouling, and suitable range of mass concentration and particle size distribution. In situ turbidimeters are widely used. They provide reliable data where the point measurements can be reliably correlated to the river's mean cross section concentration value, effects of biological fouling can be minimized, and concentrations remain below the sensor's upper measurement limit. In situ laser diffraction instruments have similar limitations and can cost 6 times the approximate $5000 purchase price of a turbidimeter. However, laser diffraction instruments provide volumetric‐concentration data in 32 size classes. Pressure differential instruments measure mass density in a water column, thus integrating substantially more streamflow than a point measurement. They are designed for monitoring medium‐to‐large concentrations, are generally unaffected by biological fouling, and cost about the same as a turbidimeter. However, their performance has been marginal in field applications. Acoustic Doppler profilers use acoustic backscatter to measure suspended sediment concentrations in orders of magnitude more streamflow than do instruments that rely on point measurements. The technology is relatively robust and generally immune to effects of biological fouling. Cost of a single‐frequency device is about double that of a turbidimeter. Multifrequency arrays also provide the potential to resolve concentrations by clay silt versus sand size fractions. Multifrequency hydroacoustics shows the most promise for revolutionizing collection of continuous suspended sediment data by instruments that require only periodic calibration for correlation to mean concentrations in river cross sections. Broad application of proven suspended sediment surrogate technologies has the potential to revolutionize fluvial sediment monitoring. Once applied, benefits could be enormous, providing for safer, more frequent and consistent, arguably more accurate, and ultimately less expensive sediment data for managing the world's sedimentary resources.
A 265‐year reconstruction of Lake Erie water levels based on North Pacific tree rings
Authors: Wiles Gregory C. , Krawiec Anne C. , D'Arrigo Rosanne D.
Published: March 2009

A dendroclimatic reconstruction based on tree ring chronologies from the Gulf of Alaska (GOA) explains 50% of the variance in annual Lake Erie levels. Temperature‐sensitive ring‐width series from the GOA are strongly and negatively correlated with annual lake levels, reflecting the Pacific North American (PNA) teleconnection pattern. Phases of the PNA are linked to variable circulation patterns that provide moisture to the Lake Erie basin, determining lake levels. The reconstruction extends back 265 years and shows that annual lake levels were high during the mid 1700s, the mid to late 1800s and the late 1900s. Relative low stands occurred during the late 1700s and early 1900s. The highest lake levels in the reconstruction are found over the past few decades, as seen in the observed record. Multidecadal‐scale fluctuations in the Lake Erie reconstruction underscore the importance of Pacific Decadal Variability in determining levels in the Great Lakes.
ISG15 modification of filamin B negatively regulates the type I interferon‐induced JNK signalling pathway
Authors: Jeon Young Joo , Choi Joon Seok , Lee Jung Yun , Yu Kyung Ryun , Kim Sangman Michael , Ka Seung Hyeun , Oh Kyu Hee , Il Kim Keun , Zhang Dong‐Er , Bang Ok Sun , Ha Chung Chin
Published: March 2009

Interferon (IFN)‐induced signalling pathways have essential functions in innate immune responses. In response to type I IFNs, filamin B tethers RAC1 and a Jun N‐terminal kinase (JNK)‐specific mitogen‐activated protein kinase (MAPK) module—MEKK1, MKK4 and JNK—and thereby promotes the activation of JNK and JNK‐mediated apoptosis. Here, we show that type I IFNs induce the conjugation of filamin B by interferon‐stimulated gene 15 (ISG15). ISGylation of filamin B led to the release of RAC1, MEKK1 and MKK4 from the scaffold protein and thus to the prevention of sequential activation of the JNK cascade. By contrast, blockade of filamin B ISGylation by substitution of Lys 2467 with arginine or by knockdown of ubiquitin‐activating enzyme E1‐like (UBEL1) prevented the release of the signalling molecules from filamin B, resulting in persistent promotion of JNK activation and JNK‐mediated apoptosis. These results indicate that filamin B ISGylation acts as a negative feedback regulatory gate for the desensitization of type I IFN‐induced JNK signalling.
Midzone organization restricts interpolar microtubule plus‐end dynamics during spindle elongation
Authors: Fridman Vladimir , Gerson‐Gurwitz Adina , Movshovich Natalia , Kupiec Martin , Gheber Larisa
Published: March 2009

To study the dynamics of interpolar microtubules (iMTs) in Saccharomyces cerevisiae cells, we photobleached a considerable portion of the middle region of anaphase spindles in cells expressing tubulin‐green fluorescent protein (GFP) and followed fluorescence recovery at the iMT plus‐ends. We found that during anaphase, iMTs show phases of fast growth and shrinkage that are restricted to the iMT plus‐ends. Our data indicate that iMT plus‐end dynamics are regulated during mitosis, as fluorescence recovery was faster in intermediate anaphase (30 s) compared with long (100 s) and pre‐anaphase (80 s) spindles. We also observed that deletion of Cin8, a microtubule‐crosslinking kinesin‐5 motor protein, reduced the recovery rate in anaphase spindles, indicating that Cin8 contributes to the destabilization of iMT plus‐ends. Finally, we show that in cells lacking the midzone organizing protein Ase1, iMTs are highly dynamic and are exchangeable throughout most of their length, indicating that midzone organization is essential for restricting iMT dynamics.
Oxygen and carbon dioxide transport in time-dependent blood flow past fiber rectangular arrays
Authors: Zierenberg Jennifer R. , Fujioka Hideki , Hirschl Ronald B. , Bartlett Robert H. , Grotberg James B.
Published: March 2009

The influence of time-dependent flows on oxygen and carbon dioxide transport for blood flow past fiber arrays arranged in in-line and staggered configurations was computationally investigated as a model for an artificial lung. Both a pulsatile flow, which mimics the flow leaving the right heart and passing through a compliance chamber before entering the artificial lung, and a right ventricular flow, which mimics flow leaving the right heart and directly entering the artificial lung, were considered in addition to a steady flow. The pulsatile flow was modeled as a sinusoidal perturbation superimposed on a steady flow while the right ventricular flow was modeled to accurately depict the period of flow acceleration (increasing flow) and deceleration (decreasing flow) during systole followed by zero flow during diastole. It was observed that the pulsatile flow yielded similar gas transport as compared to the steady flow, while the right ventricular flow resulted in smaller gas transport, with the decrease increasing with Re. The pressure drop across the fiber array (a measure of the resistance), work (an indicator of the work required of the right heart), and shear stress (a measure of potential blood cell activation and damage) are lowest for steady flow, followed by pulsatile flow, and then right ventricular flow. The pressure drop, work, shear stress, and Sherwood numbers (a measure of the gas transport efficiency) decrease with increasing porosity and are smaller for AR<1 as compared to AR>1 (AR is the distance between fibers in the flow direction/distance between fibers in direction perpendicular to flow), although for small porosities the Sherwood numbers are of similar magnitude. In general, for any fiber array geometry, high pressure drop, work, and shear stresses correlate with high Sherwood numbers, and low pressure drop, work, and shear stresses correlate with low Sherwood numbers creating a need for a compromise between pressure drop/work/shear stresses and gas transport.
Dielectric constant at x-band microwave frequencies for multiferroic BiFeO3 thin films
Authors: Abdul Ahad Faris B. , Hung D. S. , Yao Y. D. , Lee S. F. , Tu C. S. , Wang T. H. , Chen Y. Y. , Fu Y. P.
Published: March 2009

The magnetic-induced dielectric responses of BiFeO3 (BFO) thin films were measured at the X-band microwave frequency ranged from 7 to 12.5 GHz. The measurement was given initially by a high-precision cavity microwave resonator without magnetic field. Both the real and imaginary parts of the permittivity showed its dielectric property as a function of the measuring frequency. The X-band dielectric responses of the BFO thin film were then measured by a controlled magnetic field at room temperature. The data demonstrated up to 2.2% dielectric tunability by using only 3.46 kOe magnetic field at TE107 mode (9.97705 GHz).