bluuebunny/crossref_metadata_2025 huggingface dataset:
Probabilistic risk analysis of groundwater remediation strategies
Authors: Bolster D. , Barahona M. , Dentz M. , Fernandez‐Garcia D. , Sanchez‐Vila X. , Trinchero P. , Valhondo C. , Tartakovsky D. M.
Published: June 2009

Heterogeneity of subsurface environments and insufficient site characterization are some of the reasons why decisions about groundwater exploitation and remediation have to be made under uncertainty. A typical decision maker chooses between several alternative remediation strategies by balancing their respective costs with the probability of their success or failure. We conduct a probabilistic risk assessment (PRA) to determine the likelihood of the success of a permeable reactive barrier, one of the leading approaches to groundwater remediation. While PRA is used extensively in many engineering fields, its applications in hydrogeology are scarce. This is because rigorous PRA requires one to quantify structural and parametric uncertainties inherent in predictions of subsurface flow and transport. We demonstrate how PRA can facilitate a comprehensive uncertainty quantification for complex subsurface phenomena by identifying key transport processes contributing to a barrier's failure, each of which is amenable to uncertainty analysis. Probability of failure of a remediation strategy is computed by combining independent and conditional probabilities of failure of each process. Individual probabilities can be evaluated either analytically or numerically or, barring both, can be inferred from expert opinion.
Seismic observations of transient subglacial water‐flow beneath MacAyeal Ice Stream, West Antarctica
Authors: Winberry J. Paul , Anandakrishnan Sridhar , Alley Richard B.
Published: June 2009

New seismic observations of harmonic tremors beneath MacAyeal Ice Stream, West Antarctica are reported. Each of the two tremor events that we recorded during a six week period had sustained arrival of 3 Hz energy for approximately 10 minutes. During that time the source location migrated a few kilometers. The harmonic nature of the tremors is interpreted as the result of resonance in subglacial water‐filled cracks and conduits. The duration, monochromatic nature, and movement of the tremor indicate that the source mechanism is likely flow in the subglacial water system resulting from the discharge from a small subglacial lake. Our results suggest that the subglacial water system produces repeated, small outburst floods, with possible implications for ice‐stream dynamics.
P‐V‐T relations of wadsleyite determined by in situ X‐ray diffraction in a large‐volume high‐pressure apparatus
Authors: Katsura Tomoo , Shatskiy Anton , Manthilake M. A. Geeth M. , Zhai Shuangmeng , Yamazaki Daisuke , Matsuzaki Takuya , Yoshino Takashi , Yoneda Akira , Ito Eiji , Sugita Mitsuhiro , Tomioka Natotaka , Nozawa Akifumi , Funakoshi Ken‐ichi
Published: June 2009

The volume of Mg2SiO4 wadsleyite has been precisely measured at pressures of 11 to 20 GPa and temperatures of 300 to 2100 K by means of in situ X‐ray diffraction in a multi‐anvil apparatus. The fixed isothermal bulk modulus KT0 = 169.2 GPa gives its pressure derivative K′T0 = 4.1(1). The fixed Debye temperature θ0 = 814 K gives a Grüneisen parameter at ambient pressure γ0 = 1.64(2) and its logarithmic volume dependence q = 1.5(1). The pressure derivative of the isothermal bulk modulus, Anderson‐Grüneisen parameter and thermal expansion coefficient at ambient pressure are found to be (∂KT/∂T)P = −0.021(1) GPa/K, δT = 5.5(2), α0 = 2.31(3) × 10−5 + 1.18(3) × 10−8 (T − 300) K−1. The pressure and volume dependence of thermal expansion coefficient of wadsleyite is the smallest among those of the mantle minerals. The adiabatic temperature gradient in the upper part of the mantle transition zone is 0.34(1) K/km.
Hydraulic properties of adsorbed water films in unsaturated porous media
Authors: Tokunaga Tetsu K.
Published: June 2009

Adsorbed water films strongly influence residual water saturations and hydraulic conductivities in porous media at low saturations. Hydraulic properties of adsorbed water films in unsaturated porous media were investigated through combining Langmuir's film model with scaling analysis, without use of any adjustable parameters. Diffuse double‐layer influences are predicted to be important through the strong dependence of adsorbed water film thickness (f) on matric potential (ψ) and ion charge (z). Film thickness, film velocity, and unsaturated hydraulic conductivity are predicted to vary with z−1, z−2, and z−3, respectively. In monodisperse granular media, the characteristic grain size (λ) controls film hydraulics through λ−1 scaling of (1) the perimeter length per unit cross‐sectional area over which films occur, (2) the critical matric potential (ψc) below which films control flow, and (3) the magnitude of the unsaturated hydraulic conductivity when ψ < ψc. While it is recognized that finer‐textured sediments have higher unsaturated hydraulic conductivities than coarser sands at intermediate ψ, the λ−1 scaling of hydraulic conductivity predicted here extends this understanding to very low saturations where all pores are drained. Extremely low unsaturated hydraulic conductivities are predicted under adsorbed film‐controlled conditions (generally <0.1 mm a−1). On flat surfaces, the film hydraulic diffusivity is shown to be constant (invariant with respect to ψ).
Phylogenetic composition and properties of bacteria coexisting with the fungus Hypholoma fasciculare in decaying wood
Authors: Valášková Vendula , de Boer Wietse , Klein Gunnewiek Paulien JA , Pospíšek Martin , Baldrian Petr
Published: June 2009

White-rot fungi are major degraders of woody materials in terrestrial environments because of their ability to decompose lignin. However, little is known on the possible associations of white-rot fungi with other microorganisms during wood decay. We investigated the numbers, community composition and functional traits of bacteria present in natural wood samples under advanced decay by the white-rot basidiomycete Hypholoma fasciculare. The wood samples contained high numbers of cultivable bacteria (0.2–8 × 109 colony forming units (CFU) per g of dry wood). Most cultivable bacteria belonged to Proteobacteria and Acidobacteria (75% and 23% of sequences, respectively). The same phyla were also found to be dominant (59% and 23%, respectively) using a non-culturable quantification technique, namely, direct cloning and sequencing of 16sRNA genes extracted from wood. Bacteria that could be subcultured consisted of acid-tolerant strains that seemed to rely on substrates released by lignocellulolytic enzyme activities of the fungus. There were no indications for antagonism (antibiosis) of the bacteria against the fungus.
Experimental Hyperlipidemia Dramatically Reduces Access of Insulin to Canine Skeletal Muscle
Authors: Chiu Jenny D. , Kolka Cathryn M. , Richey Joyce M. , Harrison Lisa N. , Zuniga Edward , Kirkman Erlinda L. , Bergman Richard N.
Published: June 2009

A complex sequence of steps is required for insulin to cause glucose uptake. Impairment of any one of these steps can contribute to insulin resistance. We observed the effect of insulin resistance induced by hyperlipidemia on the dynamics of insulin injected into skeletal muscle. Basal insulin euglycemic clamps (0.2 mU/min/kg) with or without lipid infusions (20% at 1.5 ml/min) were done on anesthetized dogs. Sequential insulin doses were administered by intramuscular injection directly into the vastus medialis of one hindlimb, using the contralateral leg for comparison. Intramuscular insulin injection in normal animals caused a clear dose‐dependent increment in interstitial insulin levels, as well as dose‐dependent increase in leg glucose uptake. In a second group of animals, lipid was infused before and during intramuscular insulin injection to cause systemic increase in free fatty acids (FFAs). In sharp contrast, systemic lipid infusion caused insulin resistance, indicated by reduced glucose infusion required to maintain euglycemia, and prevented injection‐induced increase in lymphatic insulin and leg glucose uptake observed without lipid. The injected insulin was instead detected in the venous outflow from the leg. Lipid infusion caused intramuscular insulin to be diverted from interstitium into the capillary circulation, preventing a rise in intersitial insulin and any increase in local leg glucose uptake. The diversion of insulin from the interstitium under hyperlipidemic conditions may play a role in the insulin resistance observed coincident with elevated nocturnal FFAs as is observed in obesity.
Evidence for Three Novel QTLs for Adiposity on Chromosome 2 With Epistatic Interactions: The NHLBI Family Heart Study
Authors: Feitosa Mary F. , North Kari E. , Myers Richard H. , Pankow James S. , Borecki Ingrid B.
Published: June 2009

We sought to identify quantitative trait loci (QTLs) by genome‐wide linkage analysis for BMI and waist circumference (WC) exploring various strategies to address heterogeneity including covariate adjustments and complex models based on epistatic components of variance. Because cholesterol‐lowering drugs and diabetes medications may affect adiposity and risk of coronary heart disease, we excluded subjects medicated for hypercholesterolemia and hyperglycemia. The evidence of linkage increased on 2p25 (BMI: lod = 1.59 vs. 2.43, WC: lod = 1.32 vs. 2.26). Because environmental and/or genetic components could mask the effect of a specific locus, we investigated further whether a QTL could influence adiposity independently of lipid pathway and dietary habits. Strong evidence of linkage on 2p25 (BMI: lod = 4.31; WC: lod = 4.23) was found using Willet's dietary factors and lipid profile together with age and sex in adjustment. It suggests that lipid profile and dietary habits are confounding factors for detecting a 2p25 QTL for adiposity. Because evidence of linkage has been previously detected for BMI on 7q34 and 13q14 in National Heart, Lung, and Blood Institute Family Heart Study (NHLBI FHS), and for diabetes on 15q13, we investigated epistasis between chromosome 2 and these loci. Significant epistatic interactions were found between QTLs 2p25 and 7q34, 2q37 and 7q34, 2q31 and 13q14, and 2q31–q36 and 15q13. These results suggest multiple pathways and factors involving genetic and environmental effects influencing adiposity. By taking some of these known factors into account, we clarified our linkage evidence of a QTL on 2p25 influencing BMI and WC. The 2p25, 2q24–q31, and 2q36–q37 showed evidence of epistatic interaction with 7q34, 13q14, and 15q13.
Maternal Obesity and Breast‐feeding Practices Among White and Black Women
Authors: Liu Jihong , Smith Michael G. , Dobre Mirela A. , Ferguson James E.
Published: June 2009

Despite the increase in obesity among women of reproductive ages, few studies have considered maternal obesity as a risk factor for breast‐feeding success. We tested the hypothesis that women who are obese (BMI = 30–34.9) and very obese (BMI ≥35) before pregnancy are less likely to initiate and maintain breast‐feeding than are their normal‐weight counterparts (BMI = 18.5–24.9) among white and black women. Data from 2000 to 2005 South Carolina Pregnancy Risk Assessment Monitoring System (PRAMS) were used. The overall response rate was 71.0%; there were 3,517 white and 2,846 black respondents. Black women were less likely to initiate breast‐feeding and breast‐fed their babies for a shorter duration than white women. Compared to normal‐weight white women, very obese white women were less likely to initiate breast‐feeding (odds ratio: 0.63; 95% confidence interval (CI) = 0.42, 0.94) and more likely to discontinue breast‐feeding within the first 6 months (hazard ratio (HR) = 1.89; 95% CI: 1.39, 2.58). Among black women, prepregnancy BMI was neither associated with breast‐feeding initiation nor with breast‐feeding continuation within the first 6 months. Because very obese white women are less likely to initiate or continue breast‐feeding than other white women, health professionals should be aware that very obese white women need additional breast‐feeding support. Lower rates of breast‐feeding among black women suggest that they should continue to be the focus of the programs and policies aimed at breast‐feeding promotion in the United States.
Perceived Stress and Weight Gain in Adolescence: A Longitudinal Analysis
Authors: van Jaarsveld Cornelia H.M. , Fidler Jennifer A. , Steptoe Andrew , Boniface David , Wardle Jane
Published: June 2009

Although perceived stress has been hypothesized to be a risk factor for obesity, epidemiological studies relating stress to weight gain have shown mixed results. We examined prospective associations between perceived stress and changes in waist circumference and BMI in a large study of adolescents. As part of the Health and Behaviour in Teenagers Study (HABITS), height, weight, and waist circumference were measured annually in 4,065 adolescents aged from 11 to 16. Waist and BMI standard deviation scores (SDS) were used as indices of adiposity. Adolescents completed a measure of perceived stress each year, from which mean stress scores over the 5‐year period were also calculated and divided by tertile into lower, moderate, and higher stress. Associations between perceived stress at each year and adiposity 1–4 years later and also adiposity trajectories over the whole period in relation to mean stress were investigated. Analyses were adjusted for age, sex, ethnicity, socioeconomic deprivation, pubertal timing, and smoking. Perceived stress in any year was not related prospectively to increases in waist or BMI SDS 1–4 years later, nor was there any evidence that higher stress over the whole period was associated with greater gains in waist or BMI SDS. However, waist and BMI SDS were significantly higher in the moderate‐ and higher‐stress groups than the lower‐stress group across the whole 5‐year period. Persistent stress was associated with higher waist circumference and BMI in adolescence, but did not lead to differential changes over 5 years.
Prevalence of Obesity Among Children With Chronic Conditions
Authors: Chen Alex Y. , Kim Sue E. , Houtrow Amy J. , Newacheck Paul W.
Published: June 2009

New evidence suggests that children with chronic conditions may be predisposed to overweight and obesity. This study provides prevalence estimate of obesity for children and adolescents with select chronic conditions. We analyzed reported height and weight and the corresponding BMI from 46,707 subjects aged 10–17 years collected by the National Survey of Children's Health (NSCH‐2003). Our main outcome measure was the prevalence of obesity (defined as ≥95th percentile of the sex‐specific BMI for age growth charts), adjusted for underlying demographic and socioeconomic factors. We found that the prevalence of obesity among children 10–17 years of age without a chronic condition was 12.2% (95% confidence interval (CI) 11.5–13.0); the prevalence of obesity for children with asthma was 19.7% (19.5–19.9); with a hearing/vision condition was 18.4% (18.2–18.5); with learning disability was 19.3% (19.2–19.4); with autism was 23.4% (23.2–23.6); and with attention‐deficit/hyperactivity disorder was 18.9% (18.7–19.0). Our findings suggest that children 10–17 years of age with select chronic conditions were at increased risk for obesity compared to their counterparts without a chronic condition.
12/15‐Lipoxygenase Products Induce Inflammation and Impair Insulin Signaling in 3T3‐L1 Adipocytes
Authors: Chakrabarti Swarup K. , Cole Banumathi K. , Wen Yeshao , Keller Susanna R. , Nadler Jerry L.
Published: June 2009

Inflammation and insulin resistance associated with visceral obesity are important risk factors for the development of type 2 diabetes, atherosclerosis, and the metabolic syndrome. The 12/15‐lipoxygenase (12/15‐LO) enzyme has been linked to inflammatory changes in blood vessels that precede the development of atherosclerosis. The expression and role of 12/15‐LO in adipocytes have not been evaluated. We found that 12/15‐LO mRNA was dramatically upregulated in white epididymal adipocytes of high‐fat fed mice. 12/15‐LO was poorly expressed in 3T3‐L1 fibroblasts and was upregulated during differentiation into adipocytes. Interestingly, the saturated fatty acid palmitate, a major component of high fat diets, augmented expression of 12/15‐LO in vitro. When 3T3‐L1 adipocytes were treated with the 12/15‐LO products, 12‐hydroxyeicosatetranoic acid (12(S)‐HETE) and 12‐hydroperoxyeicosatetraenoic acid (12(S)‐HPETE), expression of proinflammatory cytokine genes, including tumor necrosis factor‐α (TNF‐α), monocyte chemoattractant protein 1 (MCP‐1), interleukin 6 (IL‐6), and IL‐12p40, was upregulated whereas anti‐inflammatory adiponectin gene expression was downregulated. 12/15‐LO products also augmented c‐Jun N‐terminal kinase 1 (JNK‐1) phosphorylation, a known negative regulator of insulin signaling. Consistent with impaired insulin signaling, we found that insulin‐stimulated 3T3‐L1 adipocytes exhibited decreased IRS‐1(Tyr) phosphorylation, increased IRS‐1(Ser) phosphorylation, and impaired Akt phosphorylation when treated with 12/15‐LO product. Taken together, our data suggest that 12/15‐LO products create a proinflammatory state and impair insulin signaling in 3T3‐L1 adipocytes. Because 12/15‐LO expression is upregulated in visceral adipocytes by high‐fat feeding in vivo and also by addition of palmitic acid in vitro, we propose that 12/15‐LO plays a role in promoting inflammation and insulin resistance associated with obesity.
Rescue of anaemia and autoimmune responses in SOD1-deficient mice by transgenic expression of human SOD1 in erythrocytes
Authors: Iuchi Yoshihito , Okada Futoshi , Takamiya Rina , Kibe Noriko , Tsunoda Satoshi , Nakajima Osamu , Toyoda Kazuyo , Nagae Ritsuko , Suematsu Makoto , Soga Tomoyoshi , Uchida Koji , Fujii Junichi
Published: June 2009

Oxidative stress has been implicated as a cause of various diseases such as anaemia. We found that the SOD1 [Cu,Zn-SOD (superoxide dismutase)] gene deficiency causes anaemia, the production of autoantibodies against RBCs (red blood cells) and renal damage. In the present study, to further understand the role of oxidative stress in the autoimmune response triggered by SOD1 deficiency, we generated mice that had the hSOD1 (human SOD1) transgene under regulation of the GATA-1 promoter, and bred the transgene onto the SOD1−/− background (SOD1−/−;hSOD1tg/+). The lifespan of RBCs, levels of intracellular reactive oxygen species, and RBC content in SOD1−/−;hSOD1tg/+ mice, were approximately equivalent to those of SOD1+/+ mice. The production of antibodies against lipid peroxidation products, 4-hydroxy-2-nonenal and acrolein, as well as autoantibodies against RBCs and carbonic anhydrase II were elevated in the SOD1−/− mice, but were suppressed in the SOD1−/−;hSOD1tg/+ mice. Renal function, as judged by blood urea nitrogen, was improved in the transgenic mice. These results rule out the involvement of a defective immune system in the autoimmune response of SOD1-deficient mice, because SOD1−/−;hSOD1tg/+ mice carry the hSOD1 protein only in RBCs. Metabolomic analysis indicated a shift in glucose metabolism to the pentose phosphate pathway and a decrease in the energy charge potential of RBCs in SOD1-deficient mice. We conclude that the increase in reactive oxygen species due to SOD1 deficiency accelerates RBC destruction by affecting carbon metabolism and increasing oxidative modification of lipids and proteins. The resulting oxidation products are antigenic and, consequently, trigger autoantibody production, leading to autoimmune responses.
Immunocytochemical techniques reveal multiple, distinct cellular pools of PtdIns4P and PtdIns(4,5)P2
Authors: Hammond Gerald R. V. , Schiavo Giampietro , Irvine Robin F.
Published: June 2009

PtdIns4P is the major precursor for the synthesis of the multifunctional plasma membrane lipid, PtdIns(4,5)P2. Yet PtdIns4P also functions as a regulatory lipid in its own right, particularly at the Golgi apparatus. In the present study we define specific conditions that enable preservation of several organellar membranes for the immunocytochemical detection of PtdIns4P. We report distinct pools of this lipid in both Golgi and plasma membranes, which are synthesized by different PI4K (phosphatidylinositol 4-kinase) activities, and also the presence of PtdIns4P in cytoplasmic vesicles, which are not readily identifiable as PI4K containing trafficking intermediates. In addition, we present evidence that the majority of PtdIns4P resides in the plasma membrane, where it is metabolically distinct from the steady-state plasma membrane pool of PtdIns(4,5)P2.
The 5′ terminal uracil of let-7a is critical for the recruitment of mRNA to Argonaute2
Authors: Felice Kristin M. , Salzman David W. , Shubert-Coleman Jonathan , Jensen Kevin P. , Furneaux Henry M.
Published: June 2009

Small RNAs modulate gene expression by forming a ribonucleoprotein complex with Argonaute proteins and directing them to specific complementary sites in target nucleic acids. However, the interactions required for the recruitment of the target nucleic acid to the ribonucleoprotein complex are poorly understood. In the present manuscript we have investigated this question by using let-7a, Argonaute2 and a fully complementary mRNA target. Importantly, we have found that recombinant Argonaute2 is sufficient to direct let-7a guided cleavage of mRNA. Thus this model system has allowed us to investigate the mechanistic basis of silencing in vitro and in vivo. Current models suggest that Argonaute proteins bind to both the 5′ and 3′ termini of the guide RNA. We have found that the termini of the let-7a microRNA are indeed critical, since circular let-7a does not support mRNA cleavage. However, the 5′ end is the key determinant, since its deletion abrogates activity. Surprisingly, we have found that alteration of the 5′ terminal uracil compromises mRNA cleavage. Importantly, we have found that substitution of this base has little effect upon the formation of the binary let-7a–Argonaute2 complex, but inhibits the formation of the ternary let-7a–Argonaute2–mRNA complex. Thus we conclude that the interaction of the 5′ uracil base with Argonaute2 plays a critical and novel role in the recruitment of mRNA.
High plasma homocysteine levels contribute to the risk of stroke recurrence and all-cause mortality in a large prospective stroke population
Authors: Zhang Weili , Sun Kai , Chen Jinxing , Liao Yuhua , Qin Qin , Ma Aiqun , Wang Daowen , Zhu Zhiming , Wang Yibo , Hui Rutai
Published: June 2009

Plasma homocysteine concentrations have been associated with the risk of stroke, but its relevance to secondary vascular events and mortality after stroke remains unclear because of inconsistent results from clinical trials. The aim of the present study was to investigate whether plasma homocysteine levels and the MTHFR (methylenetetrahydrofolate reductase) variant C677T contributed to the risk of stroke recurrence and all-cause mortality in a large prospective cohort of stroke patients in a Chinese population. A total of 1823 stroke patients (age, 35–74 years) were recruited during 2000–2001 and prospectively followed-up for a median of 4.5 years. During the follow-up, 347 recurrent strokes and 323 deaths from all-causes were documented. After adjustment for age, gender and other cardiovascular risk factors, a high homocysteine concentration was associated with an increased risk of 1.74-fold for stroke recurrence {RR (relative risk), 1.74 [95% CI (confidence interval), 1.3–2.3]; P<0.0001} and 1.75-fold for all-cause mortality [RR, 1.75 (95% CI, 1.3–2.4); P<0.0001] when highest and lowest categories were compared. Spline regression analyses revealed a threshold level of homocysteine for stroke recurrence. By dichotomizing homocysteine concentrations, the RRs were 1.31 (95% CI, 1.10–1.61; P=0.016) for stroke recurrence and 1.47 (95% CI, 1.15–1.88; P<0.0001) for all-cause mortality in patients with homocysteine levels ≥16 μmol/l relative to those with levels <16 μmol/l. The association of elevated plasma homocysteine concentrations with all-cause mortality was mainly due to an increased risk of cardiovascular deaths. No significant association was found between MTHFR C677T and stroke recurrence or mortality. In conclusion, our findings suggest that elevated homocysteine concentrations can predict the risk of stroke recurrence and mortality in patients with stroke.
Transient decrease in circulating dendritic cell precursors after acute stroke: potential recruitment into the brain
Authors: Yilmaz Atilla , Fuchs Tanja , Dietel Barbara , Altendorf Regina , Cicha Iwona , Stumpf Christian , Schellinger Peter D. , Blümcke Ingmar , Schwab Stefan , Daniel Werner G. , Garlichs Christoph D. , Kollmar Rainer
Published: June 2009

The role of DCs (dendritic cells) as potent mediators of inflammation has not been sufficiently investigated in stroke. Therefore, in the present study, circulating mDCPs (myeloid DC precursors), pDCPs (plasmacytoid DCPs) and tDCPs (total DCPs) were analysed by flow cytometry in (i) healthy controls (n=29), (ii) patients with ACI-S (asymptomatic cerebral infarction stenosis; n=46), (iii) patients with TIA (transient ischaemic attack; n=39), (iv) patients with AIS (acute ischaemic stroke; n=73), and (v) patients with AHS (acute haemorrhagic stroke; n=31). The NIHSS (National Institutes of Health Stroke Scale) and infarction size on a CT (computer tomography) scan were evaluated after stroke. In a patient subgroup, post-mortem immunohistochemical brain analyses were performed to detect mDCs (CD209), pDCs (CD123), T-cells (CD3) and HLA-DR. In AIS and AHS, the numbers of circulating mDCPs (P<0.005), pDCPs (P<0.005) and tDCPs (P<0.001) were significantly reduced. A significant inverse correlation was found between the NIHSS and circulating DCPs (P<0.02), as well as between hsCRP (high-sensitivity C-reactive protein) and circulating DCPs (P<0.001). Patients with large stroke sizes on a CT scan had significantly lower numbers of mDCPs (P=0.007), pDCPs (P=0.05) and tDCPs (P=0.01) than those with smaller stroke sizes. Follow-up analysis showed a significant recovery of circulating DCPs in the first few days after stroke. In the infarcted brain, a dense infiltration of mDCs co-localized with T-cells, single pDCs and high HLA-DR expression were observed. In conclusion, acute stroke leads to a decrease in circulating DCPs. Potentially, circulating DCPs are recruited from the blood into the infarcted brain and probably trigger cerebral immune reactions there.
Critically Evaluated Atomic Transition Probabilities for Sulfur SI–SXV
Authors: Podobedova L. I. , Kelleher D. E. , Wiese W. L.
Published: June 2009

Atomic transition probabilities for about 6400 allowed and forbidden lines of SI–SXV are tabulated based on a critical evaluation of recent literature sources. The transition probabilities were obtained mainly from recent sophisticated calculations carried out with complex computer codes. These tables provide data of interest for astronomical as well as laboratory plasmas. They will also be useful for the diagnostics of plasmas encountered in fusion energy research.
New International Formulation for the Viscosity of H2O
Authors: Huber M. L. , Perkins R. A. , Laesecke A. , Friend D. G. , Sengers J. V. , Assael M. J. , Metaxa I. N. , Vogel E. , Mareš R. , Miyagawa K.
Published: June 2009

The International Association for the Properties of Water and Steam (IAPWS) encouraged an extensive research effort to update the IAPS Formulation 1985 for the Viscosity of Ordinary Water Substance, leading to the adoption of a Release on the IAPWS Formulation 2008 for the Viscosity of Ordinary Water Substance. This manuscript describes the development and evaluation of the 2008 formulation, which provides a correlating equation for the viscosity of water for fluid states up to 1173K and 1000MPa with uncertainties from less than 1% to 7% depending on the state point.
A Fundamental Equation of State for 2-propanol (C3H8O) in the Extended Equation of State Format
Authors: Scalabrin G. , Stringari P.
Published: June 2009

An innovative method for the regression of a fundamental equation of state of a pure fluid was recently proposed. This technique, called an extended equation of state, adopts a framework similar to the extended corresponding states method but uses a cubic equation for the target fluid instead of the equation of state for the reference fluid, and shape functions are expressed through a multilayer feedforward neural network. The use of a neural network assures very high flexibility of the functional forms to be regressed, allowing the resulting model to represent the thermodynamic properties of a pure fluid with an accuracy comparable to that attained by state-of-the-art multiparameter equations of state. The technique is applied here to 2-propanol to derive a dedicated equation of state in a heuristic mode directly from the available experimental data. The majority of the data cover the range of temperatures from 280to600K and pressures up to 50MPa; this is also the validity range of the developed equation. For the present case, primarily due to the unfavorable situation of the data, all of the available thermodynamic properties have been used for the regression procedure in order to get the expected accuracy. The model has been validated with data for coexistence states, density, isobaric and isochoric heat capacities, and speed of sound. The obtained results are satisfactory because the proposed equation of state represents the available data within their mean experimental uncertainties.
IUPAC-NIST Solubility Data Series. 87. Rare Earth Metal Chlorides in Water and Aqueous Systems. Part 2. Light Lanthanides (Ce–Eu)
Authors: Mioduski Tomasz , Gumiński Cezary , Zeng Dewen
Published: June 2009

This is the second part of the volume devoted to solubility data of rare earth metal chlorides in water, ternary, and quaternary aqueous systems. This part covers chlorides of Ce, Pr, Nd, Pm, Sm, and Eu as the main solutes. Compilations of all available experimental data are introduced for each rare earth metal chloride with a corresponding critical evaluation. Every such evaluation contains a tabulated collection of all solubility results in water, a scheme of the water-rich part of the equilibrium LnCl3–H2O phase diagram, solubility equation(s), a selection of suggested solubility data, and a brief discussion of the multicomponent systems. Because the ternary and quaternary systems were almost never studied more than once, no critical evaluations or systematic comparisons of such data were possible. Only simple chlorides (no complexes) are treated as the input substances in this work. The literature (including a thorough coverage of papers in Chinese and Russian) has been covered through the middle of 2007.
Decomposition driven interface evolution for layers of binary mixtures. II. Influence of convective transport on linear stability
Authors: Madruga Santiago , Thiele Uwe
Published: June 2009

We study the linear stability with respect to lateral perturbations of free surface films of polymer mixtures on solid substrates. The study focuses on the stability properties of the stratified and homogeneous steady film states studied in Part I [U. Thiele, S. Madruga, and L. Frastia, Phys. Fluids 19, 122106 (2007)]. To this aim, the linearized bulk equations and boundary equations are solved using continuation techniques for several different cases of energetic bias at the surfaces corresponding to linear and quadratic solutal Marangoni effects. For purely diffusive transport, an increase in the film thickness either exponentially decreases the lateral instability or entirely stabilizes the film. Including convective transport leads to a further destabilization as compared to the purely diffusive case. In some cases the inclusion of convective transport and the related widening of the range of available film configurations (it is then able to change its surface profile) change the stability behavior qualitatively. We furthermore present results regarding the dependence of the instability on several other parameters, namely, the Reynolds number, the surface tension number, and the ratio of the typical velocities of convective and diffusive transport.
High-resolution, high-transmission soft x-ray spectrometer for the study of biological samples
Authors: Fuchs O. , Weinhardt L. , Blum M. , Weigand M. , Umbach E. , Bär M. , Heske C. , Denlinger J. , Chuang Y.-D. , McKinney W. , Hussain Z. , Gullikson E. , Jones M. , Batson P. , Nelles B. , Follath R.
Published: June 2009

We present a variable line-space grating spectrometer for soft x-rays that covers the photon energy range between 130 and 650 eV. The optical design is based on the Hettrick–Underwood principle and tailored to synchrotron-based studies of radiation-sensitive biological samples. The spectrometer is able to record the entire spectral range in one shot, i.e., without any mechanical motion, at a resolving power of 1200 or better. Despite its slitless design, such a resolving power can be achieved for a source spot as large as (30×3000) μm2, which is important for keeping beam damage effects in radiation-sensitive samples low. The high spectrometer efficiency allows recording of comprehensive two-dimensional resonant inelastic soft x-ray scattering (RIXS) maps with good statistics within several minutes. This is exemplarily demonstrated for a RIXS map of highly oriented pyrolytic graphite, which was taken within 10 min.
Digital ratemeter with fast response
Authors: Puzović J. M. , Aničin I. V.
Published: June 2009

Digital ratemeter that operates according to a self-adjusting algorithm, which at low rates automatically switches from a preset count to the preset time method, is proposed. It combines the good properties of both methods concerning the accuracy of the measured average counting rate and the response time to sudden changes of rate.
Computing the viscosity of supercooled liquids
Authors: Kushima Akihiro , Lin Xi , Li Ju , Eapen Jacob , Mauro John C. , Qian Xiaofeng , Diep Phong , Yip Sidney
Published: June 2009

We describe an atomistic method for computing the viscosity of highly viscous liquids based on activated state kinetics. A basin-filling algorithm allowing the system to climb out of deep energy minima through a series of activation and relaxation is proposed and first benchmarked on the problem of adatom diffusion on a metal surface. It is then used to generate transition state pathway trajectories in the potential energy landscape of a binary Lennard-Jones system. Analysis of a sampled trajectory shows the system moves from one deep minimum to another by a process that involves high activation energy and the crossing of many local minima and saddle points. To use the trajectory data to compute the viscosity we derive a Markov Network model within the Green–Kubo formalism and show that it is capable of producing the temperature dependence in the low-viscosity regime described by molecular dynamics simulation, and in the high-viscosity regime (102–1012 Pa s) shown by experiments on fragile glass-forming liquids. We also derive a mean-field-like description involving a coarse-grained temperature-dependent activation barrier, and show it can account qualitatively for the fragile behavior. From the standpoint of molecular studies of transport phenomena this work provides access to long relaxation time processes beyond the reach of current molecular dynamics capabilities. In a companion paper we report a similar study of silica, a representative strong liquid. A comparison of the two systems gives insight into the fundamental difference between strong and fragile temperature variations.
Complex dielectric response of ellipsoidal particles with surface conduction
Authors: Bertrand Edward A. , Endres Anthony L.
Published: June 2009

Both particle shape and surface phenomena significantly affect the effective complex dielectric properties of colloidal systems. The treatment of particle shape has generally relied on the extrapolation from the solution of the spherical case proposed by O’Konski [J. Chem. Phys. 64, 605 (1960)] that treats ellipsoidal particles possessing surface conductivity as equivalent homogeneous anisotropic ellipsoids with bulk conduction. To test this approach, we have performed a rigorous analysis of the complex dielectric response of an ellipsoidal particle with surface conductivity using the generalization of the O’Konski boundary conditions to an ellipsoidal shape. The resulting closed-form solution obtained shows that surface conduction effects are represented by an equivalent inhomogeneous anisotropic ellipsoid. For the case of a spheroidal particle, the principle axes of the effective dielectric permittivity tensor of the equivalent particle are aligned with its geometrical principal axes; the effective permittivity varies in the direction of the unique spheroidal axis. In addition, numerical results indicate that the product of the surface area to volume ratio and the specific surface conductivity completely characterizes the effect of the surface phenomena on the response of spheroidal particles with a given shape. Numerical simulations show that spherical and prolate spheroidal particles exhibit a progressive dielectric enhancement while more disklike oblate spheroidal particles undergo an initial dielectric suppression followed by a subsequent enhancement with increasing surface conduction. A comparison of our model predictions with those obtained using the O’Konski approximation revealed significant differences in the magnitude of the low-frequency dielectric enhancement and relaxation frequency for ellipsoidal particle suspensions.
Time-of-flight observation of electron swarm in methane
Authors: Hasegawa H. , Date H. , Yoshida K. , Shimozuma M.
Published: June 2009

This paper reports on the evolution of an isolated electron swarm, which is experimentally observed as spatial distributions at every moment. This observation is assumed to directly correspond to the conventional time-of-flight theory. We have measured the spatial distribution of electrons using a double-shutter technique in the drift tube, where a shutter electrode to collect electrons can be slid along the field (E/N) direction in order to capture a relative electron number at a certain range of location. As a typical parameter defined by this spatial distribution, the center-of-mass drift velocity (Wr) is determined for methane gas. The result is compared with the mean-arrival-time drift velocity (Wm) defined from the arriving electron number at fixed positions. We have also performed a theoretical analysis in which a Fourier transformed Boltzmann equation is solved to deduce both of the drift velocities from a dispersion relationship. The difference between Wr and Wm at high E/Ns (above 200 Td) is clearly ascertained in the experimental and theoretical investigations, which is attributable to the occurrence of ionization events.
Fine structure of the asymptotic expansion of cyclic integrals
Authors: Kozlowski K. K.
Published: June 2009

The asymptotic expansion of n-dimensional cyclic integrals was expressed as a series of functionals acting on the symmetric function involved in the cyclic integral. In this article, we give an explicit formula for the action of these functionals on a specific class of symmetric functions. These results are necessary for the computation of the O(1) part in the long-distance asymptotic behavior of correlation functions in integrable models.
Domain engineering in compositionally graded ferroelectric films for enhanced dielectric response and tunability
Authors: Okatan M. B. , Roytburd A. L. , Mantese J. V. , Alpay S. P.
Published: June 2009

Functional materials with nonlinear dielectric response are ideally suited for telecommunications applications and threat detection in beam-steering and frequency tuning devices. Developing the theory of wedge domain in graded ferroelectrics, we present herein a quantitative model of domain evolution and dielectric response of compositionally graded ferroelectric multilayers. We show that the domain structure adapts itself to the applied electric field via domain modification. As the applied field rises, the domains are swept away layer by layer resulting in a strong nonlinear field dependence of the dielectric constant and tunability of the multilayers. There is approximately a fivefold improvement in the small-signal dielectric response and threefold enhancement in the dielectric tunability at 400 kV cm−1 in compositionally graded (001) BaxSr1−xTiO3 [BST x/(1−x)] compared to homogeneous BST layers on (001) SrTiO3 substrate. We also demonstrate that by controlling the relative thicknesses of the layers that make up the graded heterostructure, one could further enhance the dielectric response and tunability.
Wall thickness dependent double optical bistability in gold nanotube: A physical mechanism based on local field enhancement
Authors: Zhu Jian , Liu Hai , Huang Li-Qing
Published: June 2009

The intrinsic optical bistability (OB) in a two-phase composite, a nonlinear gold nanotube embedded in a linear dielectric host, is investigated by theoretical calculation. Based on quasistatic approximation and Kerr nonlinearity, we obtain the local electric field in a certain position of the gold nanotube as a function of the incident field. In addition to the single OB, the appearance of double OB and optical tristability are also reported. It is shown that both wavelength and wall thickness can dramatically affect the optical bistable behavior of gold nanotube. Both the critical wavelength and the region of double OB decrease obviously with increasing the wall thickness. Thus double OB only appears in the thinner gold tube and is absent as the wall thickness exceeds the critical value. Furthermore, all these OB characteristics have been explained by the local field enhancement effect.
Properties of green-light-emitting anodic layers formed on Si substrates in HF/MnO2 mixed solution
Authors: Xu Yan Kai , Adachi Sadao
Published: June 2009

We report the properties of anodic layers formed on p-Si substrates in a 50% HF solution with the addition of an oxidizing agent MnO2. The structural and optical properties are investigated using scanning electron microscopy (SEM), photoluminescence (PL), PL excitation, x-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. The anodic layers formed have several unique properties. For example, they are stable in acidic solutions, HF, HCl, and CH3COOH, regardless of light illumination but are unstable in air exposure or in water regardless of light illumination and in methanol under UV illumination. The as-prepared layer emits light in the green spectral region, but an exposure in air without light illumination or in methanol with UV illumination leads to spectral redshift with increasing its intensity. The SEM image indicates that the anodic layer usually shows a double-layered (much roughened top/uniform bottom) structure. The XPS and FTIR spectroscopy support that the anodic layer is any compound of the hydroxyl group or others.
Characterization of high temperature piezoelectric crystals with an ordered langasite structure
Authors: Zhang Shujun , Zheng Yanqing , Kong Haikuan , Xin Jun , Frantz Eric , Shrout Thomas R.
Published: June 2009

Piezoelectric single crystals with the ordered langasite structure A3BC3D2O14, including Sr3TaGa3Si2O14, Sr3NbGa3Si2O14, Ca3TaGa3Si2O14, and Ca3TaAl3Si2O14 (CTAS), were studied as a function of temperature, up to 900 °C. The dielectric permittivity ε11 and piezoelectric coefficient d11 of the ordered crystals were found to be on the orders of 12–16 and 4–5 pC/N, respectively, slightly lower than langasite (La3Ga5SiO14-LGS) or langanite (La3Ga5.5Nb0.5O14) crystals which possess a disordered structure. The mechanical quality factor Q and electrical resistivity ρ, however, were found to be greatly improved at elevated temperatures ≥500 °C, being one to two orders of magnitude higher, due to cation ordering. Of particular interest is the CTAS crystal, in which, the Ga cations are totally replaced by low cost Al cations. Together with its thermally stable piezoelectric properties and high electrical resistivity, CTAS crystals offer a competitive material for high temperature sensing applications.
A generalized rule for large piezoelectric response in perovskite oxide ceramics and its application for design of lead-free compositions
Authors: Ahn Cheol-Woo , Maurya Deepam , Park Chee-Sung , Nahm Sahn , Priya Shashank
Published: June 2009

We present a general rule for the perovskite oxide ceramics: “A large piezoelectric constant in ABO3 perovskite ceramics can be obtained by tuning the weight ratio of A and B sites, WA/WB or WB/WA, to 3. Piezoelectric constant decreases significantly when WA/WB or WB/WA is in the range of 0.5–2.0, termed as forbidden zone.” A comparative analysis was conducted for broad range of materials demonstrating the applicability of proposed rule. Further based on this rule optimized compositions in BaTiO3 and alkali niobate based systems were developed. Polycrystalline ceramics in modified BaTiO3 system were found to exhibit longitudinal piezoelectric coefficient (d33) of 330 pC/N, while alkali niobate ceramics showed d33 of 294 pC/N.
Electrical properties and deep traps spectra of N-polar and Ga-polar AlGaN films grown by molecular beam epitaxy in a wide composition range
Authors: Zhuravlev K. S. , Mansurov V. G. , Protasov D. Yu. , Polyakov A. Y. , Smirnov N. B. , Govorkov A. V.
Published: June 2009

The polarity type, surface morphology, electrical properties, and deep trap spectra were studied for undoped AlxGa1−xN films (x=0–0.6) grown by molecular beam epitaxy on on-axis (0001) sapphire using composite buffers consisting of low temperature (LT) AlN nucleation layer, AlN, and AlN/AlGaN superlattice. It is shown that the films grow with N-polarity if the LT AlN layer is deposited under N-rich conditions and with Ga-polarity for the LT AlN layers deposited under Al-rich conditions. For both polarities the film morphology was acceptable for fabrication of typical GaN-based devices. It is demonstrated that the Ga-polar AlGaN films are heavily compensated p-type, with the dominant acceptors believed to be due to C. N-polar films are n type, with the residual donors pinning the Fermi level being most likely due to Si. N-polar films show a high concentration of deep electron traps.
Influence of thin porous Al2O3 layer on aluminum cathode to the Hα line shape in glow discharge
Authors: Steflekova V. , Šišović N. M. , Konjević N.
Published: June 2009

The results of the Balmer alfa line shape study in a plane cathode-hollow anode Grimm discharge with aluminum (Al) cathode covered with thin layer of porous Al2O3 are presented. The comparison with same line profile recorded with pure Al cathode shows lack of excessive Doppler broadened line wings, which are always detected in glow discharge with metal cathode. The effect is explained by the lack of strong electric field in the cathode sheath region, which is missing in the presence of thin oxide layer in, so called, spray discharge.
Dielectric charging in microwave microelectromechanical Ohmic series and capacitive shunt switches
Authors: Marcelli Romolo , Papaioannu George , Catoni Simone , De Angelis Giorgio , Lucibello Andrea , Proietti Emanuela , Margesin Benno , Giacomozzi Flavio , Deborgies François
Published: June 2009

The charging of the dielectric used for the actuation in microelectromechanical system (MEMS) devices is one of the major failure sources for switches based on this technology. For this reason, a better understanding of such an effect is vital to improve the reliability for both ground and space applications. In this paper, the expected response of MEMS switches to unipolar and bipolar dc actuation voltages has been measured and modeled. Two configurations of MEMS switches, namely, an Ohmic series and a shunt capacitive one designed for microwave applications, have been studied as a test vehicle for charging effects related to the dc actuation pads. The recorded data have been interpreted mainly through the Poole–Frenkel effect due to charge injection when a high voltage is applied to the dielectric layer. Metal-Insulator-Metal (MIM) structures have been also considered as a complementary information for the response of the dielectric material.