bluuebunny/crossref_metadata_2025 huggingface dataset:
Näherungsweise Stabilitätsuntersuchung orthotroper Kreiszylinderschalen unter Manteldruck
Authors: Hertle Robert , Hartung Josef
Published: April 2008

Die Bemessung von stabilitätsgefährdeten, orthotropen Kreiszylinderschalen unter normaltreuem Manteldruck ist weder im nationalen noch im internationalen Regelwerk umfassend behandelt. Um umfangreiche, numerische Berechnungen zu umgehen, wird, aufbauend auf der Untersuchung des Stabilitätsverhaltens orthotroper Platten unter Druck‐ und/oder Randschubbeanspruchung, ein Näherungsverfahren zur Ermittlung des idealen Manteldrucks pki entwickelt, welches es erlaubt, den Nachweis der Standsicherheit unter Rückgriff auf die in den einschlägigen Normen und Regeln verankerten Nachweisformate von Kreiszylinderschalen mit isotropen Materialeigenschaften zu führen. Es zeigt sich, dass in Abhängigkeit von Schalengeometrie, Krümmung und Grad der Orthotropie das Tragverhalten derartiger Konstruktionen näherungsweise entweder durch eine ideelle Ersatzschale mit isotroper Ersatzsteifigkeit oder durch einen radial und tangential gebetteten Kreisring beschrieben werden kann. Durch das hier vorgeschlagene Vorgehen werden die Adaptionsfragen von räumlicher, numerischer Untersuchung und normativem Nachweiskonzept – Beulspannungskurven und Teil sicherheitsbeiwerte in Abhängigkeit von der Imperfektionssensibilität – weitgehend umgangen.
Transversal traits in science education research relevant for teaching and research: A meta‐interpretative study
Authors: Lopes J. Bernardino , Silva António Alberto , Cravino José P. , Costa Nilza , Marques Luís , Campos Carlos
Published: April 2008

This study is a meta‐interpretative analysis that focuses on research conducted and published by other researchers. Concepts central to this study include global practical relevance, curriculum design, and formative situation. We analyzed 35 studies selected from 374 published studies in the years 2000 and 2001 in three journals referenced in the International Scientific Index. Using a replicable methodology developed specifically for this research, we found evidence of s clusters of variables that suggest the existence of transversal traits in the 35 science education research studies. These results form a reference framework of theoretical and practical knowledge relevant for research and practice pertaining to teaching and learning science. © 2008 Wiley Periodicals, Inc. J Res Sci Teach 45: 574–599, 2008
Epidemiology, etiology, and genetic aspects of reduction deficiencies of the lower limb
Authors: Ghanem Ismat
Published: April 2008

Although the majority of lower limb deficiencies are of sporadic occurrence and of unknown etiology, genetic factors are involved in a significant number, with variable modes of inheritance. A better-informed public is demanding advice concerning cause and recurrence. Careful scrutiny of the medical history and family tree and attention to phenotypic details may help to delineate entities. At times, specific chromosomal tests are important, mainly when there is bilateral or multiorgan involvement or when limb deficiency is associated with developmental delay and/or mental retardation. This paper is intended to refamiliarize the orthopaedic community with basic genetic aspects regulating reduction deficiencies of the lower limbs, and to emphasize on the importance and indications of genetic counseling.
Spectroelectrochemistry of cytochrome b559 in the D1–D2–Cyt b559 complex from spinach
Authors: Shibamoto Tadao , Kato Yuki , Watanabe Tadashi
Published: April 2008

The redox potential of cytochrome b559 (Cyt b559) in the D1–D2–Cyt b559 complex from spinach has been determined to be +90 ± 2 mV vs. SHE at pH 6.0, by thin‐layer cell spectroelectrochemistry for the first time. The redox potential, corresponding uniquely to the so‐called “low‐potential form”, exhibited a sigmoidal pH‐dependence from pH 4.0 to 9.0, ranging from +115 to +50 mV. An analysis of the pH‐dependence based on model equations suggests that two histidine residues coordinating to the heme iron in the protein subunits may exert electrostatic influence on the redox potential of Cyt b559.
Lil3 assembles as chlorophyll‐binding protein complex during deetiolation
Authors: Reisinger Veronika , Plöscher Matthias , Eichacker Lutz A.
Published: April 2008

Dark‐grown angiosperm seedlings are etiolated and devoid of chlorophyll. Deetiolation is triggered by light leading to chlorophyll dependent accumulation of the photosynthetic machinery. The transfer of chlorophyll to the chlorophyll‐binding proteins is still unclear. We demonstrate here that upon illumination of dark‐grown barley seedlings, two new pigment‐binding protein complexes are de novo accumulated. Pigments bound to both complexes are identified as chlorophyll a and protochlorophyll a. By auto‐fluorescence tracking and mass spectrometry, we show that exclusively Lil3 is the pigment‐binding complex subunit in both complexes.
Intracellular delivery of acetyl‐histone peptides inhibits native bromodomain–chromatin interactions and impairs mitotic progression
Authors: Nishiyama Akira , Mochizuki Kazuki , Mueller Florian , Karpova Tatiana , McNally James G. , Ozato Keiko
Published: April 2008

Bromodomains present in Brd4 and other chromatin proteins interact with acetylated histones to regulate transcription and cell growth. To study Brd4–chromatin interactions in vivo, histone H4 tail peptides were fused to a synthetic protein transduction domain (PTD) derived from the human immunodeficiency virus Tat and delivered into cultured cells. Acetyl‐H4 peptides, but not unacetylated H4 peptides inhibited real time Brd4–chromatin interactions in living cells as assessed by fluorescence recovery after photobleaching assays. The acetyl‐H4 peptides also inhibited an interaction of Brd4 with chromosomes during mitosis and reduced cell growth potential. Together, PTD‐based delivery of histone tail peptides offers a novel means to study the mechanism and biological significance of bromodomain–chromatin interactions in vivo.
Indole and other aromatic compounds activate the yeast TRPY1 channel
Authors: John Haynes W. , Zhou Xin-Liang , Su Zhen-Wei , Loukin Stephen H. , Saimi Yoshiro , Kung Ching
Published: April 2008

The yeast TRPY1 (Yvc1p) channel is activated by membrane stretch to release vacuolar Ca2+ into the cytoplasm upon osmotic upshock. Exogenously added indole greatly enhances the upshock‐induced Ca2+ release in vivo. Indole also reversibly activates the channels under patch clamp. A minimum of 10−6
M Ca2+ is needed for membrane stretch force to open TPRY1, but indole activation appears to be Ca2+ independent. A deletion of 30 residues at the predicted cytoplasmic domain, 570–600Δ, renders TRPY1 insensitive to stretch force upto 10−3
M Ca2+. Nonetheless, indole readily activates this mutant channel. Several other aromatic compounds, e.g. the antimicrobial pbens, also activate TRPY1. These compounds likely alter the innate forces in the lipid bilayer received by the channel.
Delineating the susceptibility of botulinum neurotoxins to denaturation through thermal effects
Authors: Zhou Bin , Pellett Sabine , Tepp William H. , Zhou Heyue , Johnson Eric A. , Janda Kim D.
Published: April 2008

Botulinum neurotoxins (BoNT) are the etiological agents responsible for botulism and are acknowledged terrorist threat agents. Passive immunotherapy may provide one countermeasure. Importantly, in the virtually unlimited repertoire of antibody specificities, enzyme linked immunosorbent assays (ELISA) has become an indispensable method for antibody selection. We report that of the BoNTs, BoNT/E is highly susceptible to polystyrene induced denaturation. To further dissect this result and the potential susceptibility of other BoNTs to denaturation we selected a thermal platform, which could be readily quantified using surface plasmon resonance (SPR), a primary rat spinal cord cell‐based assay and an animal lethality model.
One SmpB molecule accompanies tmRNA during its passage through the ribosomes
Authors: Bugaeva Elizaveta Y. , Shpanchenko Olga V. , Felden Brice , Isaksson Leif A. , Dontsova Olga A.
Published: April 2008

tmRNA and SmpB are the main participants of trans‐translation, a process which rescues the ribosome blocked during translation of non‐stop mRNA. While a one‐to‐one stoichiometry of tmRNA to the ribosome is generally accepted, the number of SmpB molecules in the complex is still under question. We have isolated tmRNA–ribosome complexes blocked at different steps of the tmRNA path through the ribosome and analyzed the stoichiometry of the complexes. Ribosome, tmRNA and SmpB were found in equimolar amount in the tmRNA–ribosome complexes stopped at the position of the 2nd, 4th, 5th or the 11th codons of the coding part of the tmRNA.
A dynamic expression pattern of sGαi2 protein during early period of postnatal rat brain development
Authors: López‐Aranda Manuel F. , López‐Téllez Juan F. , Blanco Eduardo , Masmudi‐Martín Mariam , Navarro‐Lobato Irene , Khan Zafar U.
Published: April 2008

The function of sGαi2 protein in central nervous system is not well understood. Therefore to explore the possible role of this protein in postnatal brain development, we have analyzed the protein expression pattern of brain obtained from rats of postnatal day 0 (P0) to P90 by dot‐blots and immunocytochemistry techniques. In dot‐blots, both nuclear and membrane fractions showed a gradual decrease from P0 to P60. Highest protein level was observed at the age of P0. There was also a trend of decline in the sGαi2 protein from P0 to P90 in brain sections stained by immunocytochemistry method. At P0, the protein labeling was highest in cerebral cortex, hippocampus, cerebellum and mitral cell layer. In cerebral cortex, a drop in the immunolabeling of sGαi2 protein was observed at P3, which was significantly increased at the age of P5. However, in striatum and olfactory tubercle, it was maintained through P0–P10 and P0–P5, respectively. Thalamus was one of the areas where labeling was not as strong as cortex, hippocampus or striatum. In contrary to other areas, immunostaining of sGαi2 in corpus‐callosum and lacunosum‐moleculare was not seen at P0 and appeared in advanced postnatal ages. A detectable level of sGαi2 protein was observed at P5 in carpus‐callosum and at P20 in lacunosum‐moleculare. A high level of sGαi2 protein in the period when cellular layer organization and synaptic innervations, synaptic connections and maturation take place, suggests for a potential role of this protein in the early postnatal brain development.
Middle Neoproterozoic syn-rifting volcanic rocks in Guangfeng, South China: petrogenesis and tectonic significance
Authors: LI WU-XIAN , LI XIAN-HUA , LI ZHENG-XIANG
Published: April 2008

Middle Neoproterozoic igneous rocks are widespread in South China, but their petrogenesis and tectonic implications are still highly controversial. The Guangfeng middle Neoproterozoic volcano-sedimentary succession was developed on a rare Sibaoan metamorphic basement (the Tianli Schists) in the southeastern Yangtze Block, South China. This paper reports geochronological, geochemical and Nd isotopic data for the volcanic rocks in this succession. The volcanic rocks consist of alkaline basalts, andesites and peraluminous rhyolites. SHRIMP U–Pb zircon age determinations indicate that they were erupted at 827±14 Ma, coeval with a widespread episode of anorogenic magmatism in South China. Despite showing Nb–Ta depletion relative to La and Th, the alkaline basalts are characterized by highly positive ɛNd(T) values (+3.1 to +6.0), relatively high TiO2and Nb contents and high Zr/Y and super-chondritic Nb/Ta ratios, suggesting their derivation from a slab melt-metasomatized subcontinental lithospheric mantle source in an intracontinental rifting setting. The andesites have significantly negative ɛNd(T) values (−9.3 to −11.1) and a wide range of SiO2contents (57.6–65.6%). They were likely generated by the mixing of fractionated basaltic melts with felsic melts derived from the Archaean metasedimentary rocks in the middle to lower crust. The rhyolites are highly siliceous and peraluminous. They are characterized by depletion in Nb, Ta, Sr, P and Ti and relatively high ɛNd(T) values (−3.0 to −4.8), broadly similar to those of the adjacentc.820 Ma peraluminous granitoids derived from the Mesoproterozoic to earliest Neoproterozoic sedimentary source at relatively shallow levels. We conclude that the Guangfeng volcanic suite is a magmatic response of variant levels of continental lithosphere (including lithospheric mantle and the lower-middle to upper crust) to the middle Neoproterozoic intracontinental rifting possibly caused by mantle plume activity.
Serological and molecular studies onDirofilaria immitisin dogs from Turkey
Authors: Simsek S. , Utuk A.E. , Koroglu E. , Rishniw M.
Published: April 2008

We estimated the prevalence ofDirofilaria immitisinfection in domestic dogs in five Turkish provinces – Sakarya, Kocaeli, Ankara, Elazig and Mersin – using a commercial ELISA kit for detecting circulating antigen and a PCR test for detecting circulating microfilarial DNA. A total of 211 whole-blood and serum samples were collected from dogs of various breeds, ages and life status (owned or stray). Sample population characteristics were recorded and examined for differences in prevalence. Additionally, we collected 15 blood samples from cats (14 owned and 1 stray) from Ankara province and used PCR to detectD. immitisinfection. Twenty-seven (12.8%) of 211 dog samples were positive forD. immitisantigen by ELISA. No differences in prevalence were observed by sex (female: 14.4%; male: 10.7%;P>0.05). The prevalence ofD. immitisinfection varied with age: 11.8% in younger dogs (0.5–2 years) and 17.5% in older dogs (3–5 years). Prevalence between stray dogs (15.2%) and owned dogs (9.3%) did not differ (P>0.05). Prevalence rates were highest in Kocaeli province (18.3%), followed by Ankara (14.8%), Sakarya (12.3%) and Mersin (10.5%) provinces. Prevalence in Elazig province was 0%. No dogs or cats had microfilarial DNA detectable by PCR.
The relationship between conscious phenomena and physical reality in behaviour control: The need for simplicity through phenomenological clarity
Authors: Behrendt Ralf-Peter
Published: April 2008

How can “predictive simulation” – as a conscious phenomenon, related to goal imagery – be interchangeable with mirroring, which is an automatic response that, from a first-person perspective, enters awareness only after the act? The correspondence between perception of another's action and execution of one's similar action may be an example of a general perception-motor interface that maps perception onto behaviour or disposition towards action, without the need for simulation.
Can the shared circuits model (SCM) explain joint attention or perception of discrete emotions?
Authors: Chakrabarti Bhismadev , Baron-Cohen Simon
Published: April 2008

The shared circuits model (SCM) is a bold attempt to explain how humans make sense of action, at different levels. In this commentary we single out five concerns: (1) the lack of a developmental account, (2) the absence of double-dissociation evidence, (3) the neglect of joint attention and joint action, (4) the inability to explain discrete emotion perception, and (5) the lack of predictive power or testability of the model. We conclude that Hurley's model requires further work before it could be seen as an improvement over earlier models.
The neural underpinnings of self and other and layer 2 of the shared circuits model
Authors: Furey Linda , Keenan Julian Paul
Published: April 2008

Differentiating self from other has been investigated at the neural level, and its incorporation into the model proposed Hurley is necessary for the model to be complete. With an emphasis on the feed-forward model in layer 2, we examine the role that self and other disruptions, including auditory verbal hallucinations (AVHs), may have in expanding the model proposed by Hurley.
Does one size fit all? Hurley on shared circuits
Authors: Goldman Alvin I.
Published: April 2008

Hurley's high level of generality suggests that a control-theoretic framework underpins all of the phenomena in question, but this is problematic. In contrast to the action-perception domain, where the control-theoretic framework certainly applies, there is no evidence that this framework equally applies to feelings and emotions, such as pain, touch, and disgust, where mirroring and simulational mindreading are also found.
The social motivation for social learning
Authors: Nielsen Mark
Published: April 2008

Through the second year, children's copying behaviour shifts from a focus on emulating to a focus on imitating. This shift can be explained by a change in focus from copying others to satisfy cognitive motivations to copying in order to satisfy social motivations. As elegant and detailed as the shared circuits model (SCM) is, it misses this crucial, motivation-based feature of imitation.
Taste learning in rodents: Compounds and individual taste cues recognition
Authors: Gallo Milagros
Published: April 2008

Contrary to the outstanding simplistic view of the taste system, learning studies show a more complex picture. Behavioral data using conditioned taste preference and aversion tasks support the idea that mixtures involve complex interactions between individual taste cues. Evidence from taste conditioned blocking, taste perceptual learning, and taste learned preferences is considered to support such a view. Greater support for research in taste learning and memory is required for a complete understanding of taste recognition.
The nature of economical coding is determined by the unique properties of objects in the environment
Authors: Handel Stephen
Published: April 2008

The physical properties that signify objects differ dramatically, so that the organization of sensory systems must reflect those differences. Although all senses may encode peripheral sensory information using across-fiber firing distributions, an economical coding system for each sense will necessarily differ. An economical code must maximize information about objects, whether they are predators or foods.
Basic tastes and basic emotions: Basic problems and perspectives for a nonbasic solution
Authors: Sander David
Published: April 2008

Contemporary behavioral and brain scientists consider the existence of so-called basic emotions in a similar way to the one described by Erickson for so-called basic tastes. Commenting on this analogy, I argue that similar basic problems are encountered in both perspectives, and I suggest a potential nonbasic solution that is tested in emotion research (i.e., the appraisal model of emotion).
The neural structure and organization of taste
Authors: Scott Thomas R.
Published: April 2008

Gustatory studies are predicated on the existence of basic tastes. Erickson questions this assumption and offers contrary evidence. Although Erickson may conflate certain concepts and demand uncommonly stringent requirements for basic tastes, his thoughtful article reminds us that the basic organization of taste is not yet settled.
Should labeled lines and pattern models be either-or? Issues of scope and definition
Authors: Stillman Jennifer A.
Published: April 2008

Erickson's conclusion that if basic tastes are not appropriate at one level, reference to labeled lines is inappropriate at any level, depends on matters of definition and scope. His population model mirrors Young's theory of color perception. However, there is evidence for distinct pathways to the cortex for two cone-opponent and one achromatic channel. Depending on the use made of key terms, sensory systems may display both across-fiber and labeled-line features.
Dynamics and structural development of metamorphic core complexes
Authors: Tirel Céline , Brun Jean‐Pierre , Burov Evgueni
Published: April 2008

The development of metamorphic core complexes (MCCs) in a thickened continental lithosphere is studied using fully coupled thermomechanical numerical code, accounting for elastic‐brittle‐ductile properties of constituent rocks. For MCCs to develop, the middle lower crust and the sub‐Moho mantle are required to be weak enough to flow laterally, so as to simultaneously feed the exhuming dome and enable the Moho to keep a flat geometry. The conditions are satisfied with initial Moho temperatures of 800°C or higher, with crustal thicknesses of 45 km or greater, and with initial effective viscosities lower than 1020 Pa s and 1022 Pa s in the lower crust and the underlying mantle, respectively. A compositional (mainly density) anomaly with the properties of granite is placed centrally in the crust to localize strain at the onset of deformation. During a first stage of “upper crust necking,” the deformation pattern is relatively symmetrical and dominated by graben formation in the upper crust. When the first ductile layers reach the surface, a second stage of “dome amplification and widening” occurs. Dome amplification is accommodated by horizontal flow in the ductile crust, giving an early symmetrical pattern of conjugate shear zones with no obvious detachment zone. The system then rapidly becomes asymmetric, with the localization of a detachment zone along one dome limb, further accommodating dome widening. Thus the exhumation process of a metamorphic dome results in the progressive development of a detachment zone. Depending on initial Moho temperature, the detachment zone can migrate in space or die out and be replaced by a new one with an opposite dip.
Draping of the local interstellar magnetic field over the heliopause
Authors: Mitchell J. J. , Cairns Iver H. , Pogorelov N. V. , Zank G. P.
Published: April 2008

A recent theory for radio events at 2–3 kHz observed by the Voyager spacecraft suggests that the emission is generated when shocks associated with global merged interaction regions (GMIRs) enter a region just beyond the heliopause nose that is primed with an enhanced level of superthermal electrons. In this GMIR/priming theory the superthermal electrons are accelerated by lower hybrid waves generated by pick‐up ions. For this acceleration to be efficient the pick‐up ion ring speed vr and the Alfvên speed vA must satisfy the inequality vr/vA ≲ 5, implying that the local magnetic field B must be sufficiently large. Here this constraint is used to predict which regions generate radio emission by calculating the draping of the interstellar magnetic field B∞ over the heliopause using the convected field equations and a gas‐dynamic simulation of the solar wind–VLISM interaction. The size and shape of the regions with large ∣B∣ are predicted to depend on the orientation of B∞ relative to the interstellar flow velocity. For sufficiently perpendicular orientations the high ∣B∣ region is a linear band parallel to B∞ in the plane of the sky, centered near where the surface is closely parallel to B∞, but the band shape is only a ∼10% effect compared with a circular surrounding region. The magnetic amplification factor increases with decreasing distance to the heliopause nose and increasingly perpendicular orientation of B∞, with factors ≳5 typical within axial and transverse distances to the nose of 5 and 35 AU, respectively. Combining the magnetic amplification with plausible neutral and plasma parameters, the constraint vr/vA ≲ 5 requires B∞ ≳ 0.06 nT for the GMIR/priming theory to operate within the draping region. A recently proposed constraint, that B be nearly perpendicular to the normal vector to the GMIR surface for effective electron acceleration by the GMIR shock, is also considered. A supporting argument is provided for the previous claim that this constraint predicts strong emission in a band perpendicular to B∞: Calculations show that the shock‐accelerated electrons produce significant emission only for distances parallel to B that are small (≈1 AU) compared with the macroscopic regions on the shock where B · ≈ 0. This predicted source orientation agrees well with observations of the source and an independent estimate of the direction of B∞ based on Lyman‐α observations. It is argued that the B · ≈ 0 constraint is a natural component of the GMIR/priming theory. The large, relatively circular nature of the draping region where vr/vA ≲ 5 will plausibly lead to the constraint B · ≈ 0 determining the intrinsic source shape in the plane of the sky.
Buoyant melting instabilities beneath extending lithosphere: 2. Linear analysis
Authors: Hernlund John W. , Stevenson David J. , Tackley Paul J.
Published: April 2008

In a companion paper, numerical models reveal that buoyant melting instabilities can occur beneath extending lithosphere for a sufficiently small mantle viscosity, extension rate, and rate of melt percolation. However, in some cases, instabilities do not develop during extension but only occur after extension slows or stops. These results are suggestive of a critical behavior in the onset of these kinds of instabilities and motivate a linear analysis to study the onset of instability in a partially melting, passively upwelling plane layer of mantle beneath extending lithosphere. The model we employ includes the effects of buoyancy arising from thermal expansion, the presence of a retained fraction of partial melt, and depletion of the solid by melt extraction. We find a critical behavior in the onset of instability controlled by melt retention buoyancy that is characterized by a “Rayleigh” number M, such that M must exceed some critical value Mcrit which depends on the efficiency of Stokes rise of a partially molten body relative to the rate of background percolation. Comparison of this theory to the numerical results in the companion paper yields a close quantitative agreement. We also find that solid depletion buoyancy can either stabilize or destabilize a partially melting layer, depending upon both the distribution of preexisting depletion and the magnitude of density changes with depth. This theory is compared with previous studies of buoyant melting instabilities beneath mid‐ocean ridges where similar behavior was reported, and it suggests that the stability of passively upwelling, partially melting mantle underlying both narrow and wide rift settings is controlled by similar processes.
Global wildland fire emissions from 1960 to 2000
Authors: Schultz Martin G. , Heil Angelika , Hoelzemann Judith J. , Spessa Allan , Thonicke Kirsten , Goldammer Johann G. , Held Alexander C. , Pereira Jose M. C. , van het Bolscher Maarten
Published: April 2008

In many regions of the world, fires are an important and highly variable source of air pollutant emissions, and they thus constitute a significant if not dominant factor controlling the interannual variability of the atmospheric composition. This paper describes the 41‐year inventory of vegetation fire emissions constructed for the Reanalysis of the Tropospheric chemical composition over the past 40 years project (RETRO), a global modeling study to investigate the trends and variability of tropospheric ozone and other air pollutants over the past decades. It is the first attempt to construct a global emissions data set with monthly time resolution over such a long period. The inventory is based on a literature review, on estimates from different satellite products, and on a numerical model with a semiphysical approach to simulate fire occurrence and fire spread. Burned areas, carbon consumption, and total carbon release are estimated for 13 continental‐scale regions, including explicit treatment of some major burning events such as Indonesia in 1997 and 1998. Global carbon emissions from this inventory range from 1410 to 3140 Tg C/a with the minimum and maximum occurring in 1974 and 1992, respectively (mean of 2078 Tg C/a). Emissions of other species are also reported (mean CO of 330 Tg/a, NOxof 4.6 Tg N/a, CH2O of 3.9 Tg/a, CH4of 15.4 Tg/a, BC of 2.2 Tg/a, OC of 17.6 Tg/a, SO2of 2.2 Tg/a). The uncertainties of these estimates remain high even for later years where satellite data products are available. Future versions of this inventory may benefit from ongoing analysis of burned areas from satellite data going back to 1982.
How does the northern‐winter wave driving of the Brewer‐Dobson circulation increase in an enhanced‐CO2 climate simulation?
Authors: Haklander A. J. , Siegmund P. C. , Sigmond M. , Kelder H. M.
Published: April 2008

Recent climate studies show that the northern‐winter wave driving of the Brewer‐Dobson circulation is enhanced if greenhouse gas concentrations increase. An explanation for this enhancement does not yet exist. In this study, the enhanced wave driving, as simulated in a doubled‐CO2 experiment with the MA‐ECHAM4 climate model, is analyzed in detail. The extratropical poleward eddy heat flux increases (decreases) in the stratosphere (troposphere) mainly due to the stationary (transient) heat‐flux component. The heat flux at 100 hPa is a measure of the stratospheric wave driving, and is found to increase by 12% in the doubled‐CO2 climate. This increase is dominated by the stationary‐wave 1 heat flux, which is also enhanced in the midlatitude troposphere. The heat flux increase at 100 hPa is almost entirely due to an increase in the longitudinal temperature variability. The latter increase is mainly due to the well‐understood sharpening of the lower‐stratospheric meridional temperature gradient.
Characterization of multiphase electrokinetic coupling using a bundle of capillary tubes model
Authors: Jackson Matthew D.
Published: April 2008

A simple bundle of capillary tubes model has been used to investigate electrokinetic coupling during the flow of water and an immiscible second phase such as air or oil. It is shown that the total electrokinetic coupling is the sum of the individual phase contributions. The electrokinetic coupling depends on the capillary size distribution and wettability. When water is the wetting phase and the second phase is nonpolar and does not contain an excess of charge, the relative coupling decreases with decreasing water saturation. Similar behavior has been observed in geologic porous media. However, when water is not the wetting phase, the coupling increases with decreasing water saturation before falling sharply to zero at the irreducible water saturation. This behavior has not been predicted before. If water is the only phase that contains an excess of charge, then the electrokinetic coupling can be described in terms of the water relative permeability and relative electrical conductivity. The model predictions suggest that multiphase electrokinetic coupling in geologic porous media depends on rock type and wettability and can be described in terms of commonly measured petrophysical properties. However, the predictions should be applied with caution because the pore space topology and pore occupancy of the model is very simple. Moreover, if the second phase is polar and contains an excess of charge, preliminary work suggests that the multiphase coupling can be significantly enhanced.
Impact of a Lisbon‐type tsunami on the U.K. coastline and the implications for tsunami propagation over broad continental shelves
Authors: Horsburgh K. J. , Wilson C. , Baptie B. J. , Cooper A. , Cresswell D. , Musson R. M. W. , Ottemöller L. , Richardson S. , Sargeant S. L.
Published: April 2008

We investigate the propagation of tsunamis toward the European shelf break, using six different initial conditions (based on the 1755 Lisbon earthquake), in order to assess the hazard to this region. Only one of our source models, an assumed earthquake magnitude of 8.7 Mw with a zonal fault orientation, resulted in significant wave heights at the U.K. coastline. Because of wave spreading, only a fraction of the tsunami energy from such an event reaches the northwest European shelf, which itself provides a further buffer through reflection and frictional dissipation. However, we found significant local reamplification due to wave interactions and resonance on the continental shelf. The maximum elevations obtained were comparable to severe winter storm conditions, but with extreme local variability in the tsunami amplitude. Our results suggest that the impact of any repeat of this event would be very sensitive to the precise location and orientation of the source deformation, as well as by complex topographic interactions on the shelf. The uncertainties arising from the combination of source orientation and bathymetric interaction suggest that any assessment of risk, for places where tsunamis are likely, should consider a large ensemble of initial conditions.
Parametric model to estimate clear‐sky longwave irradiance at the surface on the basis of vertical distribution of humidity and temperature
Authors: Dupont Jean‐Charles , Haeffelin Martial , Drobinski Philippe , Besnard Thierry
Published: April 2008

The surface downwelling longwave irradiance in clear‐sky situations is an important component of the global radiation balance. It can be measured directly using ground‐based pyrgeometers or computed using a radiative transfer code given precise information on atmospheric composition (water vapor, ozone, and aerosols) and temperature. Discrepancies between instantaneous observed and simulated values of the clear‐sky longwave irradiance are typically at the 3–10 W m−2 level (root‐mean‐square error). The discrepancies depend both on pyrgeometer and atmospheric composition uncertainties. Over the past century, many authors have worked on deriving control parameters to simulate the clear‐sky longwave irradiance using simple parameterizations. The most common control parameters found in the literature are screen‐level temperature, screen‐level water vapor density, and column integrated precipitable water. We show that reference parameterizations are able to simulate the clear‐sky longwave irradiance with an uncertainty of about 10 W m−2. Uncertainties are greater during nighttime than daytime periods. We propose a new parameterization that uses the standard input parameters and their diurnal variations to account for important effects of their vertical distribution on the simulation of clear‐sky longwave irradiance. The new parameterization allows us to reduce uncertainties in clear‐sky surface downwelling longwave irradiance simulations to better than 5 W m−2 for both daytime and nighttime situations.
Land surface temperature retrieval at high spatial and temporal resolutions over the southwestern United States
Authors: Inamdar Anand K. , French Andrew , Hook Simon , Vaughan Greg , Luckett William
Published: April 2008

Land surface temperature (LST) and its diurnal variation are important when evaluating climate change, land‐atmosphere energy exchange, and the global hydrological cycle. These characteristics are observable from satellites using thermal infrared measurements, but doing so at both high spatial and temporal resolutions has been difficult. Accurate temporal and spatial knowledge of LST is critical in global‐scale hydrological assimilation to improve estimates of soil moisture and evapotranspiration. Historically, satellite retrieval of global LST at high spatial resolutions (1 km) has relied on NOAA polar‐orbiting satellites recently augmented by Moderate Resolution Imaging Spectroradiometer (MODIS) data on board the Earth Observing System (EOS). Each satellite instrument in a polar orbit typically provides one to two observations per day. High temporal sampling of LST is achievable with geostationary satellites but at spatial resolutions is too coarse to distinguish different land surface types (4–5 km) and with lower accuracy. We describe an approach which employs MODIS data as a calibration source for Geostationary Environmental Satellite (GOES) data, then uses both data sets to yield half‐hourly LST values, at 1 km spatial resolution, and returns LST with an accuracy better than 2°C. The approach requires good cloud clearing, atmospheric correction, and an underlying LST model to propagate values between observations. Retrieved LST against ground truth data indicate the approach is accurate to about 2°C.
Radiative forcing by persistent contrails and its dependence on cruise altitudes
Authors: Rädel Gaby , Shine Keith P.
Published: April 2008

The expected increase of global air traffic raises concern over the impact of aviation on climate, for instance via the creation of persistent contrails that influence the radiative budget of the Earth. Here the radiative forcing due to persistent contrails due to potential new aircraft, which are added to the present fleet, is studied as a function of cruise altitudes. A sophisticated radiative transfer model is used to calculate the forcing, assuming a contrail cover derived from ECMWF analyses combined with information on air traffic from the AERO2k inventory for 2002. The global net forcing of the 2002 fleet is found to be 6 mW/m2 with a large uncertainty of about 50%, mainly due to the sparseness of contrail cover observations, assumptions about the optical depth of the contrails, and the small size of the net forcing, which results from a large cancellation of longwave and shortwave forcings of opposite signs. By increasing air traffic by, e.g., 10% in 2000 ft thick horizontal global layers in turn, it is found that contrails produced around 10 km have the largest impact on the radiative forcing per flown kilometer. A clear linear behavior was observed: in the most sensitive layer each percent of increase in air traffic leads to a 0.25% increased radiative forcing. A comparison between using ECMWF model outputs with different cloud schemes, allowing for or neglecting ice supersaturation, is presented.
Quantitative Preparative Native Continuous Polyacrylamide Gel Electrophoresis (QPNC-PAGE)
Authors: Kastenholz Bernd
Published: April 2008

QPNC-PAGE, or quantitative preparative native continuous polyacrylamide gel electrophoresis, is a high-resolution technique applied in biochemistry and bioinorganic chemistry to separate proteins by isoelectric point. This variant of gel electrophoresis is used by biologists to isolate active or native metalloproteins in biological samples and to resolve properly and improperly folded metal cofactor-containing proteins in complex protein mixtures.
Renormalized charge in a two-dimensional model of colloidal suspension from hypernetted chain approach
Authors: Camargo Manuel , Téllez Gabriel
Published: April 2008

The renormalized charge of a simple two-dimensional model of colloidal suspension was determined by solving the hypernetted chain approximation and Ornstein–Zernike equations. At the infinite dilution limit, the asymptotic behavior of the correlation functions is used to define the effective interactions between the components of the system and these effective interactions were compared to those derived from the Poisson–Boltzmann theory. The results we obtained show that, in contrast to the mean-field theory, the renormalized charge does not saturate, but exhibits a maximum value and then decays monotonically as the bare charge increases. The results also suggest that beyond the counterion layer near to the macroion surface, the ionic cloud is not a diffuse layer which can be handled by means of the linearized theory, as the two-state model claims, but a more complex structure is settled by the correlations between microions.
Benchmarks for electronically excited states: CASPT2, CC2, CCSD, and CC3
Authors: Schreiber Marko , Silva-Junior Mario R. , Sauer Stephan P. A. , Thiel Walter
Published: April 2008

A benchmark set of 28 medium-sized organic molecules is assembled that covers the most important classes of chromophores including polyenes and other unsaturated aliphatic compounds, aromatic hydrocarbons, heterocycles, carbonyl compounds, and nucleobases. Vertical excitation energies and one-electron properties are computed for the valence excited states of these molecules using both multiconfigurational second-order perturbation theory, CASPT2, and a hierarchy of coupled cluster methods, CC2, CCSD, and CC3. The calculations are done at identical geometries (MP2∕6-31G*) and with the same basis set (TZVP). In most cases, the CC3 results are very close to the CASPT2 results, whereas there are larger deviations with CC2 and CCSD, especially in singlet excited states that are not dominated by single excitations. Statistical evaluations of the calculated vertical excitation energies for 223 states are presented and discussed in order to assess the relative merits of the applied methods. CC2 reproduces the CC3 reference data for the singlets better than CCSD. On the basis of the current computational results and an extensive survey of the literature, we propose best estimates for the energies of 104 singlet and 63 triplet excited states.
Fabrication of heterosensitizer-junction dye-sensitized solar cells
Authors: Koo Hyung-Jun , Kim Kyungkon , Park Nam-Gyu , Hwang Suyoung , Park Chanmoo , Kim Chulhee
Published: April 2008

We report here a dye-sensitized solar cell structure having two different dyes with complementary absorption properties, which is different from the dye-cocktail method. The developed method allows two different dyes to be adsorbed on the sintered TiO2 layers without thermal decomposition, which the conventional procedure of dye-sensitized solar cell has been unable to do. The contribution of different dyes to photocurrent generation has been confirmed by incident-photon-to-current conversion efficiency (IPCE) and photocurrent transient spectroscopy. The heterosensitizer-junction type demonstrates higher IPCE than the single-sensitizer structure, thanks to complementary absorption characteristics.
The homogeneous nucleation of 1-pentanol in a laminar flow diffusion chamber: The effect of pressure and kind of carrier gas
Authors: Brus D. , Hyvärinen A.-P. , Wedekind J. , Viisanen Y. , Kulmala M. , Ždímal V. , Smolík J. , Lihavainen H.
Published: April 2008

The influence of total pressure and kind of carrier gas on homogeneous nucleation rates of 1-pentanol was investigated using experimental method of laminar flow diffusion chamber in this study. Two different carrier gases (helium and argon) were used in the total pressure range from 50to400kPa. Nucleation temperatures ranged from 265to290K for 1-pentanol-helium and from 265to285K for 1-pentanol-argon. Nucleation rates varied between 101 and 106cm−3s−1 for 1-pentanol-helium and between 102 and 105cm−3s−1 for 1-pentanol-argon. Both positive and slight negative pressure effects were observed depending on temperature and carrier gas. The trend of pressure effect was found similar for both carrier gases. Error analysis on thermodynamic properties was conducted, and the lowering of surface tension due to adsorption of argon on nucleated droplets was estimated. A quantitative overview of pressure effect is provided.
Interaction of methanol with amorphous solid water
Authors: Bahr S. , Toubin C. , Kempter V.
Published: April 2008

The interaction of methanol (MeOH) with amorphous solid water (ASW) composed of D2O molecules, prepared at 125K on a polycrystalline Ag substrate, was studied with metastable-impact-electron spectroscopy, reflection-absorption infrared spectroscopy, and temperature-programed desorption mass spectroscopy. In connection with the experiments, classical molecular dynamics (MD) simulations have been performed on a single CH3OH molecule adsorbed at the ice surface (T=190K), providing further insights into the binding and adsorption properties of the molecule at the ice surface. Consistently with the experimental deductions and previous studies, MeOH is found to adsorb with the hydroxyl group pointing toward dangling bonds of the ice surface, the CH3 group being oriented upwards, slightly tilted with respect to the surface normal. It forms the toplayer up to the onset of the simultaneous desorption of D2O and MeOH. At low coverage the adsorption is dominated by the formation of two strong hydrogen bonds as evidenced by the MD results. During the buildup of the first methanol layer on top of an ASW film the MeOH–MeOH interaction via hydrogen-bond formation becomes of importance as well. The interaction of D2O with solid methanol films and the codeposition of MeOH and D2O were also investigated experimentally; these experiments showed that D2O molecules supplied to a solid methanol film become embedded into the film.
Grain boundary behavior in varistor-capacitor TiO2-rich CaCu3Ti4O12 ceramics
Authors: Lin Yuan-Hua , Cai Jingnan , Li Ming , Nan Ce-Wen , He Jinliang
Published: April 2008

We prepared TiO2-rich CaCu3Ti4O12 (CCTO) ceramics by a solid-state sintering process and observed large nonlinear electrical and high dielectric behaviors. Microstructure and phase composition analyses show that CCTO grain-amorphous/TiO2 nanograin boundary-CCTO grain junction structures exist in these TiO2-rich CCTO ceramics, which leads to the nonlinear electrical and high dielectric properties. The temperature dependence of impedance spectroscopy and relationships between electrical current density versus applied electrical field indicate that the activation energy of the grain boundary for the TiO2-rich CCTO ceramics is almost the same as the potential barrier height and both of them are weakly independent of the doped concentration of TiO2, which supports the internal barrier layer capacitor model of Schottky barriers at the grain boundaries between semiconducting CCTO grains.
Extrinsic scaling effects on the dielectric response of ferroelectric thin films
Authors: Ihlefeld Jon F. , Vodnick Aaron M. , Baker Shefford P. , Borland William J. , Maria Jon-Paul
Published: April 2008

Scaling effects in polycrystalline ferroelectric thin films were investigated by preparing barium titanate in a manner that maintained constant composition and film thickness while allowing systematically increased grain size and crystalline coherence. The average grain dimensions ranged from 60to110nm, and temperature dependence of permittivity analysis revealed diffuse phase transitions in all cases. Maximum permittivity values ranged from 380 to 2040 for the smallest to largest sizes, respectively. Dielectric hysteresis is evident at room temperature for all materials, indicating stability of the ferroelectric phase. Comparison of permittivity values at high electric fields indicates that the intrinsic dielectric response is identical and microstructural artifacts likely have a minimal influence on film properties across the sample series. Permittivity values, however, are substantially smaller than those reported for bulk material with similar grain dimensions. X-ray line broadening measurements were taken for the grain size series at the Cornell High Energy Synchrotron Source (CHESS), which revealed coherent scattering dimensions substantially smaller than the microscopy-determined grain size. Collectively these data sets suggest that permittivity values are influenced not only by grain size but also by the mosaic structure existing within each grain, and that thin film thermal budgets, which are several hundred degrees lower than used for bulk processing, are responsible for reduced crystalline coherence, and likely the origin of degraded electromechanical response in thin film ferroelectrics.
Solid-state organic laser using self-written active waveguide with in-line Fabry–Pérot cavity
Authors: Yamashita K. , Kitanobou A. , Ito M. , Fukuzawa E. , Oe K.
Published: April 2008

A polymer-based laser structure with an in-line Fabry–Pérot cavity has been invented using a self-written active waveguide. This device has a channel waveguide structure doped with organic dye and can be automatically interconnected with input/output waveguide ports. The most noteworthy feature, which may provide us with a promising technology for the integrated optical circuit, is that the device can be directly fabricated between passive waveguiding components. In optically pumped emission measurements, laser emission was output from the in-line Fabry–Pérot device via the interconnected optical fiber.