bluuebunny/crossref_metadata_2025 huggingface dataset:
Aircraft type‐specific errors in AMDAR weather reports from commercial aircraft
Authors: Drüe C. , Frey W. , Hoff A. , Hauf Th.
Published: March 2008

AMDAR (Aircraft Meteorological DAta Relay) automated weather reports from commercial aircraft provide an increasing amount of input data for numerical weather prediction models. Previous studies have investigated the quality of AMDAR data. Few of these studies, however, have revealed indications of systematic errors dependent upon the aircraft type. Since different airlines use different algorithms to generate AMDAR reports, it has remained unclear whether a dependency on the aircraft type is caused by physical properties of the aircraft or by different data processing algorithms. In the present study, a special AMDAR dataset was used to investigate the physical type‐dependent errors of AMDAR reports. This dataset consists of AMDAR measurements by Lufthansa aircraft performing over 300 landings overall at Frankfurt Rhein/Main (EDDF/FRA) on 22 days in 2004. All of this data has been processed by the same software, implying that influences from different processing algorithms should not be expected. From the comparison of single descents to hourly averaged vertical profiles, it is shown that temperature measurements by different aircraft types can have systematic differences of up to 1 K. In contrast, random temperature errors of most types are estimated to be less than 0.3 K. It is demonstrated that systematic deviations in AMDAR wind measurements can be regarded as an error vector, which is fixed to the aircraft reference system. The largest systematic deviations in wind measurements from different aircraft types (more than 0.5 m s−1) were found to exist in the longitudinal direction (i.e. parallel to the flight direction). Copyright © 2008 Royal Meteorological Society
Can multi‐model combination really enhance the prediction skill of probabilistic ensemble forecasts?
Authors: Weigel A. P. , Liniger M. A. , Appenzeller C.
Published: March 2008

The success of multi‐model ensemble combination has been demonstrated in many studies. Given that a multi‐model contains information from all participating models, including the less skilful ones, the question remains as to why, and under what conditions, a multi‐model can outperform the best participating single model. It is the aim of this paper to resolve this apparent paradox.

The study is based on a synthetic forecast generator, allowing the generation of perfectly‐calibrated single‐model ensembles of any size and skill. Additionally, the degree of ensemble under‐dispersion (or overconfidence) can be prescribed. Multi‐model ensembles are then constructed from both weighted and unweighted averages of these single‐model ensembles.

Applying this toy model, we carry out systematic model‐combination experiments. We evaluate how multi‐model performance depends on the skill and overconfidence of the participating single models. It turns out that multi‐model ensembles can indeed locally outperform a ‘best‐model’ approach, but only if the single‐model ensembles are overconfident. The reason is that multi‐model combination reduces overconfidence, i.e. ensemble spread is widened while average ensemble‐mean error is reduced. This implies a net gain in prediction skill, because probabilistic skill scores penalize overconfidence. Under these conditions, even the addition of an objectively‐poor model can improve multi‐model skill. It seems that simple ensemble inflation methods cannot yield the same skill improvement.

Using seasonal near‐surface temperature forecasts from the DEMETER dataset, we show that the conclusions drawn from the toy‐model experiments hold equally in a real multi‐model ensemble prediction system. Copyright © 2008 Royal Meteorological Society
Morphological and photoluminescence study of porous thin SiC layer grown onto silicon
Authors: Bourenane K. , Keffous A. , Kechouache M. , Nezzal G. , Boukezzata A. , Kerdja T.
Published: March 2008

A porous SiC layer was fabricated by anodization of a 1.6 µm‐thin SiC layer deposited onto p‐type Si(100) substrate by pulsed laser deposition (PLD), using a hot‐pressed 6H‐SiC(p) as sputtered target. P‐type porous SiC layers were realized by anodization in HF/ethylene glycol (ETG) electrolyte (1:1 by vol.) at different etching times. The properties of the porous SiC layer formed by this method were investigated by SIMS, SEM, Fourier transform Infra‐Red spectroscopy (FT‐IR) and photoluminescence (PL). The results show that the growth layer was crystalline, with the photoluminescent spectra showing a blue band emission. In addition, the results clearly indicate an increase in PL intensity by 10 times of magnitude compared to that exhibited by the unetched sample. Copyright © 2008 John Wiley & Sons, Ltd.
Investigation of methods to enhance the secondary ion yields in TOF‐SIMS of organic samples
Authors: Heile A. , Lipinsky D. , Wehbe N. , Delcorte A. , Bertrand P. , Felten A. , Houssiau L. , Pireaux J.‐J. , De Mondt R. , Van Royen P. , Van Vaeck L. , Arlinghaus H. F.
Published: March 2008

In addition to structural information, detailed knowledge of the local chemical environment proves to be of ever greater importance, for example for the development of new types of materials as well as for specific modifications of surfaces and interfaces in multiple fields of materials science, or various biomedical and chemical applications. But the ongoing miniaturization, and therefore, reduction of the amount of material available for analysis constitute a challenge to the detection limits of analytical methods.

In the case of time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS), several methods of secondary ion yield enhancement have been proposed. This article focuses on the investigation of the effects of two of these methods, metal‐assisted SIMS and polyatomic primary ion (PI) bombardment. For this purpose, thicker layers of organic molecules (polymers and dyes), both pristine, and metallized with different amounts of gold, were analyzed using monoatomic (Ar+, Ga+, Xe+, Bi+) and polyatomic (SF5+, Bi3+, C60+) PIs. It was found that polyatomic ions generally induce a significant increase of the secondary ion yield. On the other hand, with gold deposition, a yield enhancement can only be detected for monoatomic ion bombardment. Copyright © 2008 John Wiley & Sons, Ltd.
Burnout, critical incidents and social support in security guards
Authors: Vanheule Stijn , Declercq Frederic , Meganck Reitske , Desmet Mattias
Published: March 2008

The present study examines whether the experience of a critical incident (CI) is associated with higher burnout scores; whether strong social support is associated with reduced burnout scores; and whether social support moderates the relationship between a CI and burnout scores. Security guards (n = 530) filled out the Maslach Burnout Inventory, the Self‐Rating Inventory for Post‐traumatic Stress Disorder and the Social Support List. The experience of a CI was reported by 41.1 per cent of the participants, which explained a significant amount of variance in the participants' burnout scores. Everyday emotional support and social companionship were negatively related to burnout. Emotional support with problems showed a positive association with burnout. The authors suggest that the first two forms of social support may function as buffers, whereas the latter could have an aggravating effect on burnout complaints. No significant interaction effects between social support and CI were present. This indicates that, in the present study, social support did not have a moderating effect on the relationship between a CI and burnout. Relations between social support and burnout are discussed, as are limitations of this study and suggestions for further research. Copyright © 2008 John Wiley & Sons, Ltd.
Shift between carnivory and omnivory in stream stonefly predators
Authors: Miyasaka Hitoshi , Genkai‐Kato Motomi
Published: March 2008

Omnivory can have profound effects on the trophic dynamics of communities and ecosystems, as they may interact with multiple trophic levels simultaneously. Some species of large‐bodied stoneflies may be viewed as omnivores rather than true carnivores even at later nymphal stages. We evaluated the seasonal change in the diet of stonefly predators by analyzing their stable isotope ratio, gut contents, physiological activity, and food availability. A two‐source‐based mixing model based on stable isotope analysis revealed that stoneflies shifted their diet between carnivory in summer and omnivory in winter—despite the higher availability of animal prey in winter. The gut content analysis showed that swift prey (mayflies) were consumed in the summer, whereas sluggish prey (Chironomidae) were consumed in the winter. The physiological activity of stoneflies also declined markedly in winter. These results suggest that, in winter, stoneflies foraged on a mixture of Chironomidae and algae. It appears that omnivory in some stream consumers is related to the seasonal change in temperature‐dependent physiological activity, rather than prey availability.
New classification and score for tibial hemimelia
Authors: Weber Michael
Published: March 2008

Purpose

Previous classifications of tibial malformations are no longer sufficient and practical for clinics and treatment. They are not precisely defined, include incorrect pathological–anatomical definitions, are related to X-ray diagnosis only, miss complete formal types of malformation, or describe too complex concepts not useful for clinical applications (Jones et al., J Bone Joint Surg B 60:31–39, 1978; Kalamchi and Dawe, J Bone Joint Surg B 67:581–584, 1985; Henkel et al., Arch Orthop Trauma Surg 93:1–19, 1978). More precise preoperative diagnosis, including by sonography and MRI and experienced intraoperative analysis of anatomical structures ensure exact description of the pathological–anatomical situation which can be used because of new potential in therapy. Until now, no score was available for detection of additional limb malformations and, therefore, clinical and scientific comparison of the different tibial reduction deficiencies, especially in respect to the success of therapy, was not sufficiently realisable. A new classification and score is presented reflecting the improved therapy currently available.

Methods

In this classification and score the main pathological findings of the complete leg are included (coxa–femur–patella–tibia–fibula–pes), with specific importance of the tibia. Tibial malformations are divided into seven main groups and five of them into two subgroups. The cartilaginous anlage of the tibia which has not yet received much attention in the literature plays an important role in this classification. Only seven main types of tibial defect have to be recognized and, if necessary, additional defects of the whole leg, including the function of the affected parts, can be summarized in a-five-class-system.

Results

With this classification and this score system which was evaluated on 95 affected limbs, with a sex ratio of 51%:49% (male:female), right:left affection, and unilateral:bilateral affection also, we found the sequence of the distribution of types as follows: 61% of cases with type-VII, 15% with type-III, 6% with type-I, 6% with type-V, 5% with type-II, 3% with type-IV, and 3% with type-VI. In comparison with the Jones et al. (J Bone Joint Surg B 60:31–39, 1978), Kalamchi and Dawe (J Bone Joint Surg B 67:581–584, 1985) and Henkel et al. (Arch Orthop Trauma Surg 93:1–19, 1978) classifications the tibial defects in the presented classification are detected more precisely, the pathological anatomical terms are correctly used, the whole leg and all main functions are included and, thus, reference to therapeutical possibilities is given.

Conclusions

The new classification and the score system allow simple, therapeutically relevant, and comprehensive classification and, additionally, scientific comparison of the different pattern of defects described by diverse authors. For daily clinical use the tibial classification only is preferred.
Children's daily living activities during immobilization of upper-limb fractures with an above- or below-elbow cast
Authors: Aviv Barak , Bar-On Elhanan , Weigl Daniel , Becker Tal , Katz Kalman
Published: March 2008

Background

The purpose of this prospective study was to assess the impact of cast immobilization on the activities of daily living in children with fractured upper limbs.

Methods

Using the Activities Scale for Kids (ASK), 52 consecutive children (17 girls, 35 boys), aged 5–15 years (mean, 9 years), with upper limb fractures treated by means of above- or below-elbow casts were assessed. The files were reviewed for background and fracture-related data.

Results

Mean score of the above-elbow group was 65.4 ± 15.5 points on the ASK capability domain (ASK-c) (with cast) and 98.7 ± 3 points on the ASK-performance domain (without cast). Corresponding scores for the below-cast group were 89.8 ± 13 and 99.5 ± 2. Factors that positively affected overall function were older age, male sex, shorter duration of pain, and less displacement. On multivariate analysis, only age proved to be a potential predictive factor. Cast position and hand dominance had no effect. The specific activities affected were personal hygiene, dressing, making a snack, and reaching high objects.

Conclusions

To ease their children's adjustment to forearm cast immobilization after fractures, parents should be educated in the areas of daily living that may be affected. This is particularly true for younger children with more displaced fractures that cause more pain.
Expression of recombinant anticoagulant hirudin in the differentiated cultures of the porcine mammary epithelial cell line SI‐PMEC
Authors: Sun Y.L. , Chou Y.C. , Kuan T.C. , Tu C.F. , Lin C.S.
Published: March 2008

To express recombinant proteins in the spontaneously immortalized porcine mammary epithelial cell line (SI‐PMEC) currently established in our laboratory, a chemically synthesized DNA fragment encoding the anticoagulant hirudin was used to construct a mammalian expression vector under the control of the goat β‐casein regulatory sequence. The vector, named pGB562/Hi, was transfected into the SI‐PMEC cells to yield pGB562/Hi/SI‐PMEC. The pGB562/Hi/SI‐PMEC cells expressed recombinant hirudin only when they were differentiated into functional structures by growth on a Matrigel‐coated petri dish supplemented with the lactogenic hormone prolactin. The differentiated pGB562/Hi/SI‐PMEC cells produced about 0.5–0.6 μg of recombinant hirudin/mg of total cellular protein. These results suggest that the established SI‐PMEC cells have pharmaceutical potential to inducibly express bioactive heterogeneous proteins.
Hyperthermia in combination with oxidative stress induces autophagic cell death in HT‐29 colon cancer cells
Authors: Chen Fei , Wang Chia‐Chi , Kim Eugene , Harrison Lawrence E.
Published: March 2008

The purpose of this study was to evaluate the mechanism of ROS‐induced hyperthermic cell death in a colon cancer cell line. HT‐29 colon cancer cells were exposed to heat (43 °C) in the presence of tert‐butyl hydroperoxide (t‐BOOH). t‐BOOH combined with hyperthermia significantly decreased cell viability as compared with t‐BOOH or hyperthermia alone. This decrease in cell numbers was associated with retardation in the S phase transit and not through apoptosis. Cell death was noted to be accompanied by specific features characteristic of autophagy: the presence of cytoplasmic autophagic vacuoles; autophagosome membrane association of microtubule‐associated protein light chain 3; accumulation of acidic vesicular organelles; and increased incorporation of MDC in the autophagosome. Thermal sensitization through modulation of cellular ROS may represent a novel approach to increase the efficacy of hyperthermia as an anticancer modality.
Crystal structure of the Clostridium limosum C3 exoenzyme
Authors: Vogelsgesang Martin , Stieglitz Benjamin , Herrmann Christian , Pautsch Alex , Aktories Klaus
Published: March 2008

C3‐like toxins ADP‐ribosylate and inactivate Rho GTPases. Seven C3‐like ADP‐ribosyltransferases produced by Clostridium botulinum, Clostridium limosum, Bacillus cereus and Staphylococcus aureus were identified and two representatives – C3bot from C. botulinum and C3stau2 from S. aureus – were crystallized. Here we present the 1.8 Å structure of C. limosum C3 transferase C3lim and compare it to the structures of other family members. In contrast to the structure of apo‐C3bot, the canonical ADP‐ribosylating turn turn motif is observed in a primed conformation, ready for NAD binding. This suggests an impact on the binding mode of NAD and on the transferase reaction. The crystal structure explains why auto‐ADP‐ribosylation of C3lim at Arg41 interferes with the ADP‐ribosyltransferase activity of the toxin.
Human fortilin is a molecular target of dihydroartemisinin
Authors: Fujita Takayuki , Felix Kumar , Pinkaew Decha , Hutadilok-Towatana Nongporn , Liu Zhihe , Fujise Ken
Published: March 2008

Dehydroartemisinin (DHA) is an effective anti‐malaria agent. Fortilin is an anti‐apoptotic molecule overexpressed in many human cancers. Here, we show that DHA binds human fortilin, increases the ubiquitination of fortilin, shortens fortilin's half‐life in a proteasome‐dependent fashion, and reduces cellular levels of fortilin in varieties of cells. DHA induced DNA fragmentation in U2OS cells in a fortilin‐dependent manner. The fortilin‐knocked‐down cells were less susceptible—and fortilin‐overexpressing cells more susceptible—to DHA than were wild‐type cells, suggesting that apoptotic effects of DHA are—at least partly—conferred through fortilin. Together, these data suggest that fortilin is a molecular target of DHA. DHA and its derivative may prove to be viable anti‐cancer agents in fortilin‐overexpressing cancers.
The effect of prenatal nicotine on mRNA of central cholinergic markers and hematological parameters in rat fetuses
Authors: Mao Caiping , Yuan Xin , Zhang Hong , Lv Juanxiu , Guan Junchang , Miao Liyan , Chen Linqi , Zhang Yuying , Zhang Lubo , Xu Zhice
Published: March 2008

A number of studies have demonstrated the influence of nicotine on fetal development. This study determined the expression of choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT), and high‐affinity choline transporter (CHT1) in the forebrain and hindbrain following chronic prenatal nicotine exposure in the rat fetus (maternal rats were subcutaneously injected with nicotine at different gestation periods). We also measured the effect of chronic nicotine exposure on fetal blood pO2, pCO2, pH, Na+ and K+ concentrations, as well as lactic acid levels. Maternal nicotine exposure during pregnancy was associated with a decrease in fetal pO2 coupled with a significant increase in pCO2 and lactic acid as well as restricted fetal growth. Additionally, maternal nicotine administration also reduced ChAT, VAChT, and CHT1 mRNA levels in the fetal brain. Nicotine‐induced fetal hypoxic responses and reduced cholinergic marker expression in the brain were more severe when nicotine was started in early gestation. Our results provide new information about the effects of repeated exposure to nicotine in utero on the expression of central ChAT, VAChT, and CHT1 in the rat fetus. These results indicate that repeated hypoxic episodes or/and a direct effect of nicotine on the central cholinergic system during pregnancy may contribute to brain developmental problems in fetal origin.
RNAi‐induced down‐regulation of Mecp2 expression in the rat brain
Authors: Jin Jing , Bao Xinhua , Wang Hansen , Pan Hong , Zhang Yuzhi , Wu Xiru
Published: March 2008

The MECP2 (methyl‐CpG‐binding protein 2) gene has been implicated in the pathogenesis of Rett Syndrome. A rat model with a down‐regulated Mecp2 was established using a recombinant lentiviral vector expressing small hairpin RNA of the rat Mecp2 gene. Four recombinant vectors were constructed by inserting sequences of small hairpin RNA targeting the rat Mecp2 gene. To determine which vector resulted in optimal down‐regulation, rat skin fibroblasts were transfected with four recombinant vectors, respectively. The recombinant vector mecp2‐sh‐1 decreased expression of Mecp2 mRNA and protein relative to the Control group. 12–24 h after birth, neonatal rat pups were divided into three groups, Re‐Lenti group (injected with recombinant lentiviral vector, mecp2‐sh‐1), Lenti group (injected with lentivirus containing no inserted sequences) and a non‐injected Control group (Control group). Rats in the injection groups were given intraventricular injections. 7 days and 21 days following injection, no inflammation was observed in the rat brain in the two injected groups, whereas EGFP expression was readily detectable. Sensory‐motor reflexes were transiently abnormal in Re‐Lenti group, whereas no abnormality was observed in either Control group. Mecp2 mRNA was lower in the hippocampus and cerebral cortex in the Re‐Lenti group relative to the Lenti and Control groups. Although no typical RTT like symptoms were observed, the neonatal rats injected with recombinant lentivirus displayed some transient neurobehavioral abnormalities during early development. Bdnf mRNA expression decreased in the hippocampus, supporting the hypothesis that Bdnf may be a target gene of MeCP2 in the CNS.
PINCHING THEOREMS FOR A COMPACT MINIMAL SUBMANIFOLD IN A COMPLEX PROJECTIVE SPACE
Authors: KON MAYUKO
Published: March 2008

We give a formula for the Laplacian of the second fundamental form of an n-dimensional compact minimal submanifold M in a complex projective space CPm. As an application of this formula, we prove that M is a geodesic minimal hypersphere in CPm if the sectional curvature satisfies K≥1/n, if the normal connection is flat, and if M satisfies an additional condition which is automatically satisfied when M is a CR submanifold. We also prove that M is the complex projective space CPn/2 if K≥3/n, and if the normal connection of M is semi-flat.
ON THE METHOD OF APPROXIMATION FOR EVOLUTIONARY INCLUSIONS OF PSEUDOMONOTONE TYPE
Authors: KASYANOV PAVLO , MELNIK VALERY , VALERO JOSÉ
Published: March 2008

For a large class of operator inclusions, including those generated by maps of pseudomonotone type, we obtain a general theorem on existence of solutions. We apply this result to some particular examples. This theorem is proved using the method of difference approximations.
ON THE STABILITY OF A MIXED-TYPE LINEAR AND QUADRATIC FUNCTIONAL EQUATION
Authors: NAKMAHACHALASINT PAISAN
Published: March 2008

We give the general solution of the n-dimensional mixed-type linear and quadratic functional equation, where $P_m=\{A\subset \{1,2,\ldots ,n\}: |A|=m\}$, and 1<m<n are integers.
Preface to Special Issue devoted to the memory of Sauro Tulipani
Authors: CORRADINI FLAVIO , TOFFALORI CARLO
Published: March 2008

2006 was a special year for both mathematical logic and computer science, as it celebrated Gödel's centenary. Although Gödel's work was mainly concerned with mathematics and metamathematics, the crucial role it had in the foundation of modern theoretical computer science is undeniable: for instance, one only has to remember Gödel's contributions to the birth of recursion theory as well as his part in the debate in the nineteen thirties on the subject of the Church Thesis.
Multiple-Labelled Transition Systems for nominal calculi and their logics
Authors: DE NICOLA ROCCO , LORETI MICHELE
Published: March 2008

Action-labelled transition systems (LTSs) have proved to be a fundamental model for describing and proving properties of concurrent systems. In this paper we introduce Multiple-Labelled Transition Systems (MLTSs) as generalisations of LTSs that enable us to deal with system features that are becoming increasingly important when considering languages and models for network-aware programming. MLTSs enable us to describe not only the actions that systems can perform but also their usage of resources and their handling (creation, revelation . . .) of names; these are essential for modelling changing evaluation environments. We also introduce MoMo, which is a logic inspired by Hennessy–Milner Logic and the μ-calculus, that enables us to consider state properties in a distributed environment and the impact of actions and movements over the different sites. MoMo operators are interpreted over MLTSs and both MLTSs and MoMo are used to provide a semantic framework to describe two basic calculi for mobile computing, namely μKlaim and the asynchronous π-calculus.
Model theory of exponentials on Lie algebras
Authors: MACINTYRE ANGUS
Published: March 2008

This paper presents an analysis of definitions and decidability for exponential functions on various matrix algebras. The main idea is to show that, generically, the entries of the exponential (or logarithm) of a matrix are Pfaffian functions of the entries of the matrix.
Mass‐independent fractionation of mercury isotopes in the environment
Authors: Ghosh Sanghamitra , Xu Yingfeng , Humayun Munir , Odom Leroy
Published: March 2008

The toxicity of mercury's methylated species and its biomagnification in aquatic food chains and global dispersion by the atmosphere are the cause of worldwide health problems. Recent reports have observed natural mass‐dependent fractionation in mercury isotopes, and recent theoretical work has demonstrated that isotopic separation in mercury is due primarily to nuclear field shifts (nuclear volume effect), and the magnetic spin effect gives rise to mass‐independent fractionation (MIF) of odd neutron number isotopes. Now we present analytical evidence of mass‐independent isotopic variations in mercury produced by both nuclear volume and magnetic isotope processes. Even mass number isotopes exhibit a pattern indistinguishable from that produced by mass‐dependent fractionation, with both positive and negative 199Hg and 201Hg anomalies. MIF is easier to reliably determine in Hg isotopes than mass‐dependent fractionation alone, and thus it provides a potentially important key in constraining models of mercury sources and pathways in the environment.
Constraints on the radiogenic heat production rate in the Martian interior from viscous relaxation of crustal thickness variations
Authors: Grott M. , Breuer D.
Published: March 2008

Crustal thickness variations induce lateral pressure gradients which can drive flow in the lower crust if temperatures there are sufficiently high. The absence of large scale crustal relaxation at the Argyre impact basin therefore constrains the temperatures at the base of the crust and we have computed thermal evolution models to study the influence of radiogenic heating and hydrothermal crustal cooling on lower crustal temperatures. In the presence and absence of hydrothermal crustal cooling and for an average crustal thickness of 45 km, radiogenic heating after core formation cannot have exceeded 58 and 43 pW kg−1, respectively. Furthermore, if the average crustal thickness is closer to 50 km, heating cannot have exceeded 49 and 36 pW kg−1. A better knowledge of the planet's average crustal thickness, which may be obtained from seismological experiments, could help to further constrain the planets bulk composition and even rule out some of the compositional models for Mars that have been proposed so far.
Rainfall effects on Ku‐band satellite link design in rainy tropical climate
Authors: Mandeep J. S. , Hassan S. I. S. , Tanaka K.
Published: March 2008

The performance of rain attenuation models in equatorial zones is still a debated issue due to the lack of measurements reported from these areas. Therefore,Therefore the rainfall path attenuation at 12.255 GHz measured at Universiti Sains Malaysia (USM) for three years is presented. It shows that the power law function of rain attenuation with ground rain rate deviates at very high rain rate. A comparison is made between the measured cumulative distributions and current prediction models, in order to determine which model gives the best prediction for this location.
Sources and fluxes of atmospheric trace elements to the Gulf of Aqaba, Red Sea
Authors: Chen Ying , Paytan Adina , Chase Zanna , Measures Christopher , Beck Aaron J. , Sañudo‐Wilhelmy Sergio A. , Post Anton F.
Published: March 2008

We present the first comprehensive investigation of the concentrations, fluxes and sources of aerosol trace elements over the Gulf of Aqaba. We found that the mean atmospheric concentrations of crustally derived elements such as Al, Fe and Mn (1081, 683, and 16.7 ng m−3) are about 2–3 times higher than those reported for the neighboring Mediterranean area. This is indicative of the dominance of the mineral dust component in aerosols over the Gulf. Anthropogenic impact was lower in comparison to the more heavily populated areas of the Mediterranean. During the majority of time (69%) the air masses over the Gulf originated from Europe or Mediterranean Sea areas delivering anthropogenic components such as Cu, Cd, Ni, Zn, and P. Airflows derived from North Africa in contrast contained the highest concentrations of Al, Fe, and Sr but generally lower Cu, Cd, Ni, Zn, and P. Relatively high Pb, Ni, and V were found in the local and Arabian airflows suggesting a greater influence of local emission of fuel burning. We used the data and the measured trace metal seawater concentrations to calculate residence times of dissolved trace elements in the upper 50 m surface water of the Gulf (with respect to atmospheric input) and found that the residence times for most elements are in the range of 5–37 years while Cd and V residence times are longer.
Comparison of ERA40 cloud top phase with POLDER‐1 observations
Authors: Weidle Florian , Wernli Heini
Published: March 2008

A detailed grid‐point‐based comparison of the cloud top phase derived from the 40‐year reanalyses (ERA40) of the European Centre for Medium‐Range Weather Forecasts (ECMWF) with satellite measurements is presented. For this purpose an algorithm is implemented to extract a two‐dimensional “satellite‐like” field of the cloud top phase from ERA40 data. This field is compared with cloud top phase data from the Polarization and Directionality of the Earth Reflectances (POLDER‐1) instrument which was in orbit from November 1996 to June 1997. The thermodynamic cloud phase in ERA40 data is parameterized as a function of temperature with pure liquid clouds above 0°C, pure ice clouds below −23°C and mixed clouds in between. The matching performance of clouds derived from ERA40 with clouds observed by POLDER‐1 is best in the extratropical storm track regions and over the tropical continents. Detailed comparison of the cloud top phase for grid points where both data sets indicate a cloud shows a relatively good agreement for warm (T > 0°C) and cold (T < −30°C) clouds. In the intermediate temperature range, ERA40 contains too many ice clouds compared to POLDER‐1. The comparison reveals only small seasonal variations. A slightly revised parameterization for the phase partitioning of condensed cloud water is suggested (shifting the thresholds by −10°C), which leads to a generally improved agreement between cloud top phases derived from ERA40 and POLDER‐1.
Validation of the Space Weather Modeling Framework using observations from CHAMP and DMSP
Authors: Wang H. , Ridley A. J. , Lühr H.
Published: March 2008

The Space Weather Modeling Framework (SWMF) is a flexible framework for space weather simulation, which can couple magnetosphere and ionosphere processes. This work compares ionospheric outputs from SWMF with magnetic and plasma observations from CHAMP and DMSP satellites under both quiet and storm conditions, emphasizing the dependence of the model's performance for various magnetic local times, solar wind conditions, and seasons. The model predicts the potential better in the dawn‐dusk sector then in the noon‐midnight sector. For field‐aligned currents (FACs) the model performs better on the dayside than on the nightside. In addition, there is a trend toward unsatisfactory behavior in the model as solar activity increases. The model more accurately corresponds to observations during quiet times than disturbed periods. During storms the model FACs tend to locate at ∼4° MLat more poleward than the observations. Our analysis has revealed that the model performance depends strongly on the seasons. The model underestimates the cross polar cap potential (CPCP) by about ∼50% in the summer hemisphere while overestimating it by ∼50% in the winter hemisphere. The model calculates the difference between the winter and summer hemisphere CPCP on the order of a factor of 2.5, while DMSP data show that the actual factor is around 1.3. These results reveal that the ionospheric modeling subsets lack appropriate seasonal dependence.
Endothelial Nitric Oxide Synthase Gene Single-Nucleotide Polymorphism Predicts Cerebral Vasospasm after Aneurysmal Subarachnoid Hemorrhage
Authors: Starke Robert M , Kim Grace H , Komotar Ricardo J , Hickman Zachary L , Black Eric M , Rosales Maritza B , Kellner Christopher P , Hahn David K , Otten Marc L , Edwards John , Wang Tao , Russo James J , Mayer Stephan A , Connolly Edward S
Published: March 2008

Vasospasm is a major cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage (aSAH). Studies have shown a link between single-nucleotide polymorphisms (SNPs) in the endothelial nitric oxide synthase (eNOS) gene and the incidence of coronary spasm and aneurysms. Alterations in the eNOS T-786 SNP may lead to an increased risk of post-aSAH cerebral vasospasm. In this prospective clinical study, 77 aSAH patients provided genetic material and were followed for the occurrence of vasospasm. In multivariate logistic regression analysis, genotype was the only factor predictive of vasospasm. The odds ratio (OR) for symptomatic vasospasm in patients with one T allele was 3.3 (95% confidence interval (CI): 1.1 to 10.0, P=0.034) and 10.9 for TT. Patients with angiographic spasm were 3.6 times more likely to have a T allele (95% CI: 1.3 to 9.6, P=0.013; for TT: OR 12.6). Patients with severe vasospasm requiring endovascular therapy were more likely to have a T allele (OR 3.5, 95% CI: 1.3 to 9.5, P=0.016; for TT: OR 12.0). Patients with the T allele of the eNOS gene are more likely to have severe vasospasm. Presence of this genotype may allow the identification of individuals at high risk for post-aSAH vasospasm and lead to early treatment and improved outcome.
Magnetization reversal of nanostructured tunnel junctions from prepatterned substrates
Authors: Bollero A. , Baltz V. , Dieny B. , Negulescu B. , Rickart M. , Freitas P. P. , Vogel J. , Bonfim M. , Landis S.
Published: March 2008

Nanostructured tunnel junctions with composition Al2O3∕Ta∕Ru∕Mn51.5Pt48.5∕Co90Fe10∕Al oxidized/Co90Fe10∕Ni81Fe19∕Ta were prepared on prepatterned silicon substrates, consisting of rectangular dots with dimensions as small as 100×400nm2 and different spacings. Reduced lateral dimensions lead to an enhancement of the exchange bias field by comparison to continuous films. Magnetic force microscopy images taken at remanence indicate a mixture of magnetic states corresponding to the different relative orientations of the magnetizations of the pinned and the free layers. Significant dipolar interactions between the dots also proved to contribute to the complexity of the magnetization reversal of the stacks.
Equilibrium properties of quantum water clusters by the variational Gaussian wavepacket method
Authors: Frantsuzov Pavel A. , Mandelshtam Vladimir A.
Published: March 2008

The variational Gaussian wavepacket (VGW) method in combination with the replica-exchange Monte Carlo is applied to calculations of the heat capacities of quantum water clusters, (H2O)8 and (H2O)10. The VGW method is most conveniently formulated in Cartesian coordinates. These in turn require the use of a flexible (i.e., unconstrained) water potential. When the latter is fitted as a linear combination of Gaussians, all the terms involved in the numerical solution of the VGW equations of motion are analytic. When a flexible water model is used, a large difference in the timescales of the inter- and intramolecular degrees of freedom generally makes the system very difficult to simulate numerically. Yet, given this difficulty, we demonstrate that our methodology is still practical. We compare the computed heat capacities to those for the corresponding classical systems. As expected, the quantum effects shift the melting temperatures toward the lower values.
Crystallization and thermomagnetic treatment of a Co-rich Co–Fe–Ni–Zr–B–Cu based nanocomposite alloy
Authors: Ohodnicki P. R. , Park S. Y. , Laughlin D. E. , McHenry M. E. , Keylin V. , Willard M. A.
Published: March 2008

The magnetic properties observed after various thermal-magnetic treatments for a (Co0.85Fe0.15)83.6Ni4.4Zr7B4Cu1 alloy are compared with those for a (Co0.88Fe0.12)79.4Nb2.6Si9B9 alloy of similar Co:Fe ratio which exhibited a large field induced anisotropy in previous work. The qualitative conclusions arrived at here also apply to the (Co0.85Fe0.15)88Zr7B4Cu1 alloy without Ni. For the transverse magnetic field annealed (Co0.85Fe0.15)83.6Ni4.4Zr7B4Cu1 alloy, the highest anisotropy fields HK (HK∼35–40Oe), field induced anisotropies KU (KU∼1700–2000J∕m3), and lowest coercivities HC (HC∼0.5–1.5Oe at f=3kHz) were observed for field annealed amorphous ribbons as compared to field crystallized ribbons. For the (Co0.88Fe0.12)79.4Nb2.6Si9B9 alloy, the field induced anisotropy is a maximum for field crystallized ribbons (HK∼28–45Oe, KU∼800–1800J∕m3) and the increase in dynamic coercivity (HC∼0.5–1Oe at f=3kHz) observed upon crystallization is much less dramatic. The field annealed amorphous alloy of composition (Co0.85Fe0.15)83.6Ni4.4Zr7B4Cu1 exhibited field induced anisotropies and dynamic coercivities that are competitive with the field crystallized alloys of composition (Co0.88Fe0.12)79.4Nb2.6Si9B9.
Unidirectional Pt silicide nanowires grown on vicinal Si(100)
Authors: Lim Do Kyung , Bae Sung-Soo , Choi Junghun , Lee Dohyun , Sung Da Eun , Kim Sehun , Kim J. K. , Yeom H. W. , Lee Hangil
Published: March 2008

We investigated the structure and electronic properties of unidirectional Pt2Si nanowires (NWs) grown on a Si(100)-2° off surface. We found that Pt2Si NWs were formed along the step edges of the Si(100)-2° off surface with c(4×6) reconstructions that occurred on the terraces of Si(100) using scanning tunneling microscopy and the structure of formed NWs was found to be Pt2Si by core-level photoemission spectroscopy. Moreover, we confirmed that the electronic band structures of the NWs along the NW direction are different from those perpendicular to the NWs and the surface state induced by the Pt2Si NWs was observed with a small density of state using the angle-resolved photoemission spectra.
The phase behavior of comblike block copolymer Am+1Bm/homopolymer A mixtures
Authors: Ye Xiang-Gui , Sun Zhao-Yan , Li Hong-Fei , An Li-Jia , Tong Zhen
Published: March 2008

The phase behaviors of comblike block copolymer Am+1Bm/homopolymer A mixtures are studied by using the random phase approximation method and real-space self-consistent field theory. From the spinodals of macrophase separation and microphase separation, we can find that the number of graft and the length of the homopolymer A have great effects on the phase behavior of the blend. For a given composition of comblike block copolymer, increasing the number of graft does not change the macrophase separation spinodal curve but decreases the microphase separation region. The addition of a small quantity of long-chain homopolymer A increases the microphase separation of comblike block copolymer/homopolymer A mixture. However, the addition of short-chain homopolymer A will decrease the phase separation region of comblike block copolymer/homopolymer A mixture. It is also found that the microstructure formed by diblock copolymer is easier to be swelled by homopolymer than that formed by comblike block copolymer. This can be attributed to the architecture difference between the comblike block copolymer and linear block copolymer.
Ferromagnetic resonance and superparamagnetic behavior of iron oxide nanoparticles injected in porous anodic alumina
Authors: Pasquale Massimo , Olivetti Elena S. , Coïsson Marco , Rizzi Paola , Bertotti Giorgio
Published: March 2008

Iron oxide nanoparticles with diameter around 10nm were produced and injected in 60μm thick anodic alumina membranes with pore diameters of 20 and 100nm. The structure, magnetic properties, and the ferromagnetic resonance frequency of the nanoparticles before and after injection into the columnar arrays were measured as a function of the out-of-plane applied field. The effect of dipolar interactions and clustering mechanisms of the injected nanoparticles on the static and radio frequency magnetic response is discussed.
Enhancement of ferroelectric and magnetic properties in BiFeO3 films by small amount of cobalt addition
Authors: Naganuma Hiroshi , Shimura Nozomi , Miura Jun , Shima Hiromi , Yasui Shintaro , Nishida Ken , Katoda Takashi , Iijima Takashi , Funakubo Hiroshi , Okamura Soichiro
Published: March 2008

Both the ferroelectric and magnetic properties of polycrystalline BiFeO3 films fabricated by chemical solution deposition were enhanced by adding small amounts of cobalt. Addition of 3at.% cobalt to BiFeO3 films increased the remanent polarization from 49to72μC∕cm2 and decreased the electric coercive field from 0.54to0.44MV∕cm. The ferroelectricity degraded when the cobalt concentration exceeded 9at.% due to the formation of the secondary phases of Bi2Pt. The saturation magnetization was drastically enhanced by the addition of cobalt up to 12at.%. This is because the magnetic moments are not canceled locally since the differences of magnetic moment between B-sites. The saturation magnetization decreased when the cobalt content exceeded 15at.%, thereby attributing to the formation of a nonmagnetic secondary phase of Bi2Pt. It is concluded that both ferroelectric and magnetic properties were enhanced, provided only small amount of cobalt were added to the films.
Improved current switching symmetry of magnetic tunneling junction and giant magnetoresistance devices with nano-current-channel structure
Authors: Yao Xiaofeng , Meng Hao , Zhang Yisong , Wang Jian-Ping
Published: March 2008

The asymmetry of the switching current in magnetic tunneling junction (MTJ) and giant magnetoresistance (GMR) spin torque transfer devices was reported in both theory and experiment. This is one of the key challenges for future magnetic random access memory applications. In this work, the switching symmetry was greatly improved by inserting a nano-current-channel (NCC) structure in both MTJ and GMR devices. With the NCC structure, the current induced magnetization switching is nonuniform with initiation cites induced by locally high current density. The critical switching current density in both switching directions was successfully reduced while the degree of switching asymmetry {[(JcP-AP−JcAP-P)∕JcAP-P]×100%} was improved as well.
Experimental chaotic map generated by picosecond laser pulse-seeded electro-optic nonlinear delay dynamics
Authors: Grapinet Mélanie , Udaltsov Vladimir , Jacquot Maxime , Lacourt Pierre-Ambroise , Dudley John M. , Larger Laurent
Published: March 2008

We describe experimental studies of the dynamical behavior of a recently proposed electro-optic discrete time nonlinear delay oscillator. With appropriate choice of the oscillator loop parameters and external forcing of the dynamics using a pulsed laser source, the system allows for the physical realization of a high dimensional mathematical nonlinear mapping. The dynamical features observed with this new class of discrete time delay oscillator differ significantly from those observed with similar continuous time nonlinear delay feedback oscillators and reveal the intrinsic discrete time nature of the dynamics. We also discuss specific applications to chaos communications using regularly clocked binary data.
Triplet host engineering for triplet exciton management in phosphorescent organic light-emitting diodes
Authors: Kim Sung Hyun , Jang Jyongsik , Yook Kyoung Soo , Lee Jun Yeob , Gong Myoung-Seon , Ryu Sangouk , Chang Gee-keun , Chang Ho Jung
Published: March 2008

The device performances of green phosphorescent organic light-emitting diodes with a triplet mixed host emitting layer were correlated with the energy levels and composition of the host materials. Two hole-transport-type host materials, (4,4′-N,N′-dicarbazole)biphenyl (CBP) and 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA), were combined with two electron-transport-type host materials, 1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene (TPBI) and PH1. The maximum quantum efficiency was obtained in the 5:5 mixed host in the case of TCTA:TPBI and TCTA:PH1, while CBP:PH1 showed the best performances in the 9:1 mixed host. The quantum efficiency of the green mixed host devices was improved by more than 50% compared with that of the corresponding single host devices.
Dynamics of Langmuir wave decay in two dimensions
Authors: Ziebell L. F. , Gaelzer R. , Yoon P. H.
Published: March 2008

The present paper reports on the first two-dimensional (2D) self-consistent solution of weak turbulence equations describing the evolution of electron-beam-plasma interaction in which quasilinear as well as nonlinear three-wave decay processes are taken into account. It is found that the 2D Langmuir wave decay processes lead to the formation of a quasicircular ring spectrum in wave number space. It is also seen that the 2D ring-spectrum of Langmuir turbulence leads to a tendency to isotropic heating of the electrons. These findings contain some important ramifications. First, in the literature, isotropization of energetic electrons, detected in the solar wind for instance, is usually attributed to pitch-angle scattering. The present finding constitutes an alternative mechanism, whose efficiency for other parametric regimes has to be investigated. Second, when projected onto the one-dimensional (1D) space, the 2D ring spectrum may give a false impression of Langmuir waves inverse cascading to longer wavelength regime, when in reality, the wavelength of the turbulence does not change at all but only the wave propagation angle changes. Although the present analysis excludes the induced scattering, which is another process potentially responsible for the inverse cascade, the present finding at least calls for an investigation into the relative efficacy of the inverse-cascading process in 1D vs 2D.
Dominant factors limiting efficiency of optical spin detection in ZnO-based materials
Authors: Chen W. M. , Buyanova I. A. , Murayama A. , Furuta T. , Oka Y. , Norton D. P. , Pearton S. J. , Osinsky A. , Dong J. W.
Published: March 2008

Two dominant factors limiting efficiency of optical spin detection in ZnO-based materials system are identified from time-resolved optical orientation and magneto-optical studies. The first is related to the fundamental band structure of the materials characterized by a weak spin-orbit interaction. It leads to cancellation of circular polarization from the optical transitions between the conduction band and the A and B valence band states, which would otherwise carry the desired information on spin polarization of carriers. The second limiting factor is shown to be efficient carrier/exciton spin relaxation, i.e., about 45–80ps.
Optical polarization characteristics of InGaN∕GaN light-emitting diodes fabricated on GaN substrates oriented between (101¯) and (101¯1¯) planes
Authors: Masui Hisashi , Yamada Hisashi , Iso Kenji , Nakamura Shuji , DenBaars Steven P.
Published: March 2008

Optical polarization characteristics of InGaN∕GaN light-emitting diodes (LEDs) were studied. Light-emitting diode samples were fabricated on four types of GaN substrates near (101¯0) orientation with intentional off-axis cuts of 0°, 5°, 10°, and 27° towards [0001¯]. A confocal microscope was used to characterize the optical polarization of electroluminescence at various currents. The highest polarization ratio of 0.91 was measured on samples fabricated on a 5° off-cut substrate. First moments were calculated on emission spectra to assess emission peak shifts of two polarization components. We drew a conclusion that substrate off-axis cut is a technique to improve optical polarization characteristics of nonpolar-oriented InGaN∕GaN LEDs.