bluuebunny/crossref_metadata_2025 huggingface dataset:
Referenzgruppeneffekte im Simulierten Klassenraum
Authors: Südkamp Anna , Möller Jens
Published: December 2009

Untersuchungen zum «Big-Fish-Little-Pond Effect» zeigen, dass nicht nur das akademische Selbstkonzept, sondern auch die Vergabe von Schulnoten von der schulischen Leistung der Referenzgruppe beeinflusst wird. In dieser Studie mit N = 42 Lehramtsstudierenden wurden Referenzgruppeneffekte auf Einschätzungen von Schülerleistungen experimentell untersucht. Dazu wurde die Computersimulation einer Unterrichtssituation, der Simulierte Klassenraum, verwendet. Die durchgeführten Mehrebenenanalysen ergaben einen negativen Effekt des mittleren Leistungsniveaus der Klasse auf indirekte Einschätzungen in Form von Noten: Schüler mit identischen Leistungen wurden in einer Klasse mit niedrigem mittlerem Leistungsniveau besser benotet als in einer Klasse mit höherem mittlerem Leistungsniveau. Dagegen zeigte sich kein Referenzgruppeneffekt, wenn die Probanden aufgefordert wurden, eine direkte Einschätzung der Schülerleistung vorzunehmen, bei der sie den Anteil korrekter Antworten der einzelnen Schüler angaben. Über den Referenzgruppeneffekt hinaus wird die Genauigkeit von Leistungsbeurteilungen im Simulierten Klassenraum diskutiert.
Urteilsverzerrungen in der schulischen Leistungsbeurteilung
Authors: Dünnebier Katrin , Gräsel Cornelia , Krolak-Schwerdt Sabine
Published: December 2009

Ziel der vorliegenden Studie ist es, zu untersuchen, inwieweit und unter welchen Bedingungen Ankereffekte bei der schulischen Leistungsbeurteilung wirksam werden. Dabei verstehen wir als Anker einen vorangegangenen Wert, der den urteilenden Lehrkräften vorgegeben wird und der das Urteil verzerrt. Wir verwenden in unserer Untersuchung eine vermeintliche Benotung einer vorgegebenen Leistung (Klausur) mit einer 2 (hoher Anker) oder einer 4 (niedriger Anker). Untersucht werden zwei Einflussfaktoren auf die Wirksamkeit von Ankern: Die Expertise der Urteilenden und das Verarbeitungsziel. Dabei gehen wir davon aus, dass Experten ihr Urteil dem Verarbeitungsziel anpassen können: Beim weniger bedeutsamen Ziel, sich einen ersten Eindruck über einen Schüler zu bilden, sollte sich bei Lehrer-Experten ein Ankereffekt zeigen – nicht aber bei der gravierenden, folgenschweren Empfehlung für eine Schullaufbahn, die eine merkmalsgeleitete Informationsverarbeitung voraussetzt. Bei Novizen (Studierenden des Lehramtes) sollten aufgrund der geringeren Flexibilität der Informationsverarbeitung generell Ankereffekte auftreten. In unserem Quasi-Experiment wurde den Versuchspersonen (N = 128) ein Beurteilungsfall vorgelegt, der aus einer neutralen Schülerbeschreibung, einer Klassenarbeit in Deutsch und einer in Mathematik bestand. Für die Deutscharbeiten wurde die Hypothese der Abhängigkeit des Ankereffektes von der Expertise und vom Verarbeitungsziel bestätigt. Entgegen der Erwartungen zeigte sich bei der Mathematikarbeit ein genereller Ankereffekt.
Small negative cloud‐to‐ground lightning reports at the NASA Kennedy Space Center and Air Force Eastern Range
Authors: Wilson Jennifer G. , Cummins Kenneth L. , Krider E. Philip
Published: December 2009

The NASA Kennedy Space Center (KSC) and Air Force Eastern Range (ER) use data from two cloud‐to‐ground (CG) lightning detection networks, the Cloud‐to‐Ground Lightning Surveillance System (CGLSS) and the U.S. National Lightning Detection Network™ (NLDN), and a volumetric lightning mapping array, the Lightning Detection and Ranging (LDAR) system, to monitor and characterize lightning that is potentially hazardous to launch or ground operations. Data obtained from these systems during June–August 2006 have been examined to check the classification of small, negative CGLSS reports that have an estimated peak current, ∣Ip∣ less than 7 kA, and to determine the smallest values of Ip that are produced by first strokes, by subsequent strokes that create a new ground contact (NGC), and by subsequent strokes that remain in a preexisting channel (PEC). The results show that within 20 km of the KSC‐ER, 21% of the low‐amplitude negative CGLSS reports were produced by first strokes, with a minimum Ip of −2.9 kA; 31% were by NGCs, with a minimum Ip of −2.0 kA; and 14% were by PECs, with a minimum Ip of −2.2 kA. The remaining 34% were produced by cloud pulses or lightning events that we were not able to classify.
Ground ice at the Phoenix Landing Site: Stability state and origin
Authors: Mellon Michael T. , Arvidson Raymond E. , Sizemore Hanna G. , Searls Mindi L. , Blaney Diana L. , Cull Selby , Hecht Michael H. , Heet Tabatha L. , Keller H. Uwe , Lemmon Mark T. , Markiewicz Wojciech J. , Ming Douglas W. , Morris Richard V. , Pike W. Thomas , Zent Aaron P.
Published: December 2009

A primary objective of the Phoenix mission was to examine the characteristics of high latitude ground ice on Mars. We report observations of ground ice, its depth distribution and stability characteristics, and examine its origins and history. High latitude ground ice was explored through a dozen trench complexes and landing thruster pits, over a range of polygon morphological provinces. Shallow ground ice was found to be abundant under a layer of relatively loose ice‐free soil with a mean depth of 4.6 cm, which varied by more than 10x from trench to trench. These variations can be attributed mainly to slope effects and thermal inertia variations in the overburden soil affecting ground temperatures. The presence of ice at this depth is consistent with vapor‐diffusive equilibrium with respect to a mean atmospheric water content of 3.4 × 1019 m−3, consistent with the present‐day climate. Significant ice heterogeneity was observed, with two major forms: ice‐cemented soil and relatively pure light toned ice. Ice‐cemented soils, which comprised about 90% of the icy material exposed by trenching, are best explained as vapor deposited pore ice in a matrix supported porous soil. Light toned ice deposits represent a minority of the subsurface and are thought to consist of relatively thin near surface deposits. The origin of these relatively pure ice deposits appears most consistent with the formation of excess ice by soil ice segregation, such as would occur by thin film migration and the formation of ice lenses, needle ice, or similar ice structures.
The periglacial landscape at the Phoenix landing site
Authors: Mellon Michael T. , Malin Michael C. , Arvidson Raymond E. , Searls Mindi L. , Sizemore Hanna G. , Heet Tabatha L. , Lemmon Mark T. , Keller H. Uwe , Marshall John
Published: December 2009

The Mars Scout mission Phoenix landed in the northern high latitudes of Mars in an area thought to be dominated by subsurface ground ice, and has provided a unique detailed examination of periglacial morphology and topography that is not visible from orbit. The landing site and surrounding terrain is dominated by polygonal patterned ground typical of the Martian northern plains. The polygons exhibit a gentle U‐shaped trough and rounded mound topography, with an average trough depth of 17 cm and an average surface slopes of only 6.7°. Polygons an average 4.3 m across form a pattern superimposed on all other geologic landforms, including larger 20–25 m polygons and kilometer long linear ridges. The polygon morphology and the predominance of subsurface ice‐cemented soil are consistent with the formation of subsurface “sand wedges” in a permanently frozen arid climate. Small‐scale soil furrows and cracks into the ice‐cemented soil indicate that the thermal contraction process responsible for the formation of the polygons is active today. Rocks appear to be sorted within the polygon troughs, indicating a process of cryoturbation within the permanently frozen polygons. The complexity of the patterns, crosscutting relations, and rock distributions, indicate advanced maturity of the polygon networks and shifting crack patterns, possibly facilitated by crack and wedge annealing during times of low obliquity.
Space‐time localization of inner heliospheric plasma turbulence using multiple spacecraft radio links
Authors: Richie‐Halford Adam C. , Iess L. , Tortora P. , Armstrong J. W. , Asmar S. W. , Woo Richard , Habbal Shadia Rifai , Morgan Huw
Published: December 2009

Radio remote sensing of the heliosphere using spacecraft radio signals has been used to study the near‐Sun plasma in and out of the ecliptic, close to the Sun, and on spatial and temporal scales not accessible with other techniques. Studies of space‐time variations in the inner solar wind are particularly timely because of the desire to understand and predict space weather, which can disturb satellites and systems at 1 AU and affect human space exploration. Here we demonstrate proof of concept of a new radio science application for spacecraft radio science links. The differing transfer functions of plasma irregularities to spacecraft radio uplinks and downlinks can be exploited to localize plasma scattering along the line of sight. We demonstrate the utility of this idea using Cassini radio data taken in 2001–2002. Under favorable circumstances we demonstrate how this technique, unlike other remote sensing methods, can determine center‐of‐scattering position to within a few thousandths of an AU and thickness of scattering region to less than about 0.02 AU. This method, applied to large data sets and used in conjunction with other solar remote sensing data such as white light data, has space weather application in studies of inhomogeneity and nonstationarity in the near‐Sun solar wind.
STIM and Orai proteins: players in sexual differences in hypertension-associated vascular dysfunction?
Authors: Giachini Fernanda R.C. , Webb R. Clinton , Tostes Rita C.
Published: December 2009

Sex-associated differences in hypertension have been observed repeatedly in epidemiological studies; however, the mechanisms conferring vascular protection to females are not totally elucidated. Sex-related differences in intracellular Ca2+ handling or, more specifically, in mechanisms that regulate Ca2+ entry into vascular smooth muscle cells have been identified as players in sex-related differences in hypertension-associated vascular dysfunction. Recently, new signalling components that regulate Ca2+ influx, in conditions of intracellular store depletion, were identified: STIM1 (stromal interaction molecule 1), which works as an intracellular Ca2+ sensor; and Orai1, which is a component of the CRAC (Ca2+ release-activated Ca2+) channels. Together, these proteins reconstitute store-operated Ca2+ channel function. Disturbances in STIM1/Orai1 signalling have been implicated in pathophysiological conditions, including hypertension. In the present article, we analyse evidence for sex-related differences in Ca2+ handling and propose a new hypothesis where sex-related differences in STIM/Orai signalling may contribute to hypertension-associated vascular differences between male and female subjects.
Nonlinear Franz–Keldysh effect: Two photon absorption in semiconducting quantum wires and quantum boxes
Authors: Xia Congxin , Spector Harold N.
Published: December 2009

We have performed a theoretical calculation of the two photon absorption (TPA) in semiconducting quantum wires and quantum boxes in the presence of an electric field. Because of the anisotropic nature of these nanostructures, the TPA depends on the relative orientations of the electric field, the direction of polarization of the optical field, and the direction of carrier confinement in these semiconducting nanostructures. Numerical results show that the electric field decreases the TPA in quantum wires and boxes for any direction of the electric field and optical polarization. The TPA occurs below the zero field threshold energy of the semiconducting quantum wires and quantum boxes when an electric field is present. Moreover, the TPA has more structure in quantum boxes than that in quantum wires for any direction of electric field or polarization. In addition, the ratio of the TPA in the quantum wires and boxes to that in the bulk is also calculated as a function of the photon energy both in the presence and absence of the electric field.
Electronic structure and optical properties of ZnSiO3 and Zn2SiO4
Authors: Karazhanov S. Zh. , Ravindran P. , Fjellvåg H. , Svensson B. G.
Published: December 2009

The electronic structure and optical properties of orthorhombic, monoclinic, and rhombohedral (corundum type) modifications of ZnSiO3, and of rhombohedral, tetragonal, and cubic (spinel type) modifications of Zn2SiO4 have been studied using ab initio density functional theory calculations. The calculated fundamental band gaps for the different polymorphs and compounds are in the range 2.22–4.18 eV. The lowest conduction band is well dispersive similar to that found for transparent conducting oxides such as ZnO. This band is mainly contributed by Zn 4s electrons. The carrier effective masses were calculated and compared with those for ZnO. The topmost valence band is much less dispersive and contributed by O 2p and Zn 3d electrons. From the analysis of charge density, charges residing in each site, and electron localization function, it is found that ionic bonding is mainly ruling in these compounds. The calculated optical dielectric tensors show that the optical properties of ZnSiO3 and Zn2SiO4 are almost isotropic in the visible part of the solar spectra and depend negligibly on the crystal structure. Within the 0–4 eV photon energy range, the calculated magnitude of the absorption coefficient, reflectivity, refractive index, and extinction coefficient are smaller than 103 cm−1, 0.15, 2.2, and 0.3, respectively, for all the ZnSiO3 and Zn2SiO4 phases considered in this work. This suggests that zinc silicates can be used as antireflection coatings.
Optimizing core-shell nanoparticle catalysts with a genetic algorithm
Authors: Froemming Nathan S. , Henkelman Graeme
Published: December 2009

A genetic algorithm is used with density functional theory to investigate the catalytic properties of 38- and 79-atom bimetallic core-shell nanoparticles for the oxygen reduction reaction. Each particle is represented by a two-gene chromosome that identifies its core and shell metals. The fitness of each particle is specified by how close the d-band level of the shell is to that of the Pt(111) surface, a catalyst known to be effective for oxygen reduction. The genetic algorithm starts by creating an initial population of random core-shell particles. The fittest particles are then bred and mutated to replace the least-fit particles in the population and form successive generations. The genetic algorithm iteratively refines the population of candidate catalysts more efficiently than Monte Carlo or random sampling, and we demonstrate how the average energy of the surface d-band can be tuned to that of Pt(111) by varying the core and shell metals. The binding of oxygen is a more direct measure of catalytic activity and is used to further investigate the fittest particles found by the genetic algorithm. The oxygen binding energy is found to vary linearly with the d-band level for particles with the same shell metal, but there is considerable variation in the trend across different shells. Several particles with oxygen binding energies similar to Pt(111) have already been investigated experimentally and found to be active for oxygen reduction. In this work, many other candidates are identified.
Effect of annealing on atomic ordering of amorphous ZrTaTiNbSi alloy
Authors: Yang Tsung-Han , Huang Rong-Tang , Wu Cheng-An , Chen Fu-Rong , Gan Jon-Yiew , Yeh Jien-Wei , Narayan Jagdish
Published: December 2009

In this letter, we have reported on initial stages of atomic ordering in ZrTaTiNbSi amorphous films during annealing. The atomic ordering and structure evolution were studied in Zr17Ta16Ti19Nb22Si26 amorphous films as a function of annealing temperature in the temperature range from 473 to 1173 K. Up to annealing temperature of 1173 K, the films retained amorphous structure, but the degree of disorder is increased with the increase in temperature. The formation of Si–M covalent bonds, which contributed to the local atomic arrangement, occurred in the initial stages of ordering. The bonding reactions between Si and other metal species explain the anomalous structural changes which were observed in x-ray diffraction and transmission electron microscopy. We discuss the stages of phase transformation for amorphous films as a function of annealing temperature. From these results, we propose that annealing leads to formation of random Si–M4 tetrahedron, and two observed rings, a first and second in the electron diffraction patterns compared to M–M and Si–M bond length, respectively.
The information content of electron flow through adsorbed molecular monolayers
Authors: Sherratt Paul A. J. , Cohen Hagai , Seideman Tamar
Published: December 2009

We point to the ability of noncontact measurements of electron transport via self-assembled monolayers to provide chemical, Å-resolved information about the underlying molecule. A conceptual framework is presented to model a current flow of soft electrons through a molecular monolayer to a substrate and explore the information content of this and other emerging noncontact measurements. A numerical scheme is developed where advantage is taken of the split-operator formalism to propagate the incident electronic wave function over a suitable periodic potential energy surface representing the self-assembled monolayer. The (experimentally observable) potential difference introduced by the transmitted electrons is extracted from the time-averaged electron density using the Poisson equation of classical electrostatics.
Thermal emission from finite photonic crystals
Authors: Schuler Christian J. , Wolff Christian , Busch Kurt , Florescu Marian
Published: December 2009

We present a microscopic theory of thermal emission from finite-sized photonic crystals and show that the directional spectral emissivity and related quantities can be evaluated via standard bandstructure computations without any approximation. We then identify the physical mechanisms through which interfaces modify the potentially super-Planckian radiation flow inside infinite photonic crystals, such that thermal emission from finite-sized samples is consistent with the fundamental limits set by Planck’s law. As an application, we further demonstrate that a judicious choice of a photonic crystal’s surface termination facilitates considerable control over both the spectral and angular thermal emission properties.
Dominant recombination centers in Ga(In)NAs alloys: Ga interstitials
Authors: Wang X. J. , Puttisong Y. , Tu C. W. , Ptak Aaron J. , Kalevich V. K. , Egorov A. Yu. , Geelhaar L. , Riechert H. , Chen W. M. , Buyanova I. A.
Published: December 2009

Optically detected magnetic resonance measurements are carried out to study formation of Ga interstitial-related defects in Ga(In)NAs alloys. The defects, which are among dominant nonradiative recombination centers that control carrier lifetime in Ga(In)NAs, are unambiguously proven to be common grown-in defects in these alloys independent of the employed growth methods. The defects formation is suggested to become thermodynamically favorable because of the presence of nitrogen, possibly due to local strain compensation.
An informative set of SNP markers for molecular characterisation of Australian barley germplasm
Authors: Hayden M. J. , Tabone T. L. , Nguyen T. M. , Coventry S. , Keiper F. J. , Fox R. L. , Chalmers K. J. , Mather D. E. , Eglinton J. K.
Published: December 2009

The identification of genetic variation using molecular markers is fundamental to modern plant breeding and research. The present study was undertaken to develop a resource of informative single nucleotide polymorphism (SNP) markers for molecular characterisation of Australian barley germplasm. In total, 190 SNP markers were developed and characterised using 88 elite barley lines and varieties, sampling genetic diversity relevant to Australian breeding programs, and a core set of 48 SNPs for distinguishing among the barley lines was identified. The utility of the core 48-SNP set for distinguishing barley lines and varieties using DNA extracted from grain samples was also assessed. Finally, the 48 SNPs in the core set were converted into simple PCR markers to enable co-dominant SNP genotyping on agarose gel. The SNP markers developed, and in particular the core 48-SNP set, provide a useful marker resource for assessing genetic relationships between individuals and populations of current Australian barley germplasm. They are also useful for identity and purity testing of inbred lines in research, breeding, and commercial applications.
Fauna assemblages in regrowth vegetation in tropical open forests of the Northern Territory, Australia
Authors: Woinarski J. C. Z. , Rankmore B. , Hill B. , Griffiths A. D. , Stewart A. , Grace B.
Published: December 2009

Context. World-wide, primary forest is in decline. This places increasing importance on understanding the use by biodiversity of regrowth (secondary) forest, and on the management of such regrowth. Aims. This study aimed to compare the terrestrial vertebrate assemblages in tropical eucalypt forests, regrowth in these forests (following clearing for pastoral intensification) and cleared land without regrowth, to provide evidence for developing management guidelines for regrowth vegetation in a region (the Daly catchment of the Northern Territory) subject to increasing demands for land-use intensification. Methods. The terrestrial vertebrate fauna was surveyed consistently at 43 quadrats sampling forest, 38 sampling regrowth and 19 sampling cleared land (formerly forest), and the faunal composition was compared with ordination and analysis of variance. Further analysis used generalised linear modelling to include consideration of the relative importance of disturbance (condition) of quadrats. Key results. Faunal assemblages in regrowth vegetation were found to be intermediate between cleared land and intact forest, and converged towards the faunal assemblage typical of intact forest with increase in the canopy height of the regrowth. However, even the tallest regrowth quadrats that were sampled supported relatively few hollow-associated species. The management of fire, weeds and grazing pressure substantially affected the faunal assemblages of the set of regrowth and intact forest quadrats, in many cases being a more important determinant of faunal attributes than was whether or not the quadrat had been cleared. Conclusions. In this region, regrowth vegetation has value as habitat for fauna, with this value increasing as the regrowth structure increases. The convergence of the faunal composition of regrowth vegetation to that of intact forest may be substantially affected by post-clearing management factors (including fire regime and level of grazing pressure and weed infestation). Implications. Regrowth vegetation should be afforded appropriate regulatory protection, with the level of protection increasing as the regrowth increases in stature.
Behaviour and time to unconsciousness of brushtail possums (Trichosurus vulpecula) after a lethal or sublethal dose of 1080
Authors: Littin Kate E. , Gregory Neville G. , Airey Andrea T. , Eason Charles T. , Mellor David J.
Published: December 2009

Context. Sodium fluoroacetate (1080) is a vertebrate pesticide used in several countries, including New Zealand, where it is the main pesticide for controlling brushtail possums (Trichosurus vulpecula) – a significant agricultural and conservation pest. There is growing concern internationally about the impacts of vertebrate pesticides, including 1080, on pest animal welfare. Aims. Behavioural changes and time to loss of consciousness of possums after 1080 ingestion in carrot baits were determined to compare the animal welfare impacts with other possum pesticides. Methods. Eight lethally dosed possums and eight that consumed a dose intended to be sublethal were observed until death or recovery but not handled. Another nine lethally dosed possums were handled to determine responses to stimuli, indicating time to loss of consciousness. Key results. Unhandled, lethally dosed possums died after 11 h 26 min ± 1 h 55 min (mean ± s.e.m.). Half had abnormal appearances and postures 1 h 50 min ± 9 min after consuming baits. Seven showed retching, and three vomited, over 27 ± 12 min from 2 h 53 min ± 13 min. Lack of coordination began 3 h 37 min ± 32 min after dosing, then possums spent most of the time until death lying, showing spasms and tremors. Five showed seizures while lying prostrate. Possums receiving a nominally sublethal dose all showed signs of poisoning, including abnormal postures, lethargy, lack coordination, retching, spasms or tremors, and a cessation of grooming, feeding and activity. One died 18 h 15 min after dosing, experiencing two seizures within 30 min of death. Response to handling, indicating total loss of consciousness, was lost in two possums before death. Conclusions. Possums ingesting a lethal dose of 1080 experienced ~9.5 h of changed behaviour and lost consciousness close to death, although awareness was likely reduced sometime beforehand. Possums ingesting a nominally sublethal dose experienced some effects of poisoning. Implications. These impacts are intermediate compared with other possum pesticides in New Zealand. Nevertheless, the potential for consciousness during and after retching and seizures is undesirable for animal welfare. Further work is encouraged on alternatives to 1080 and means of reducing its impact on animal welfare.
Adaptive response by state-dependent inactivation
Authors: Friedlander Tamar , Brenner Naama
Published: December 2009

Many membrane channels and receptors exhibit adaptive, or desensitized, response to a strong sustained input stimulus. A key mechanism that underlies this response is the slow, activity-dependent removal of responding molecules to a pool which is unavailable to respond immediately to the input. This mechanism is implemented in different ways in various biological systems and has traditionally been studied separately for each. Here we highlight the common aspects of this principle, shared by many biological systems, and suggest a unifying theoretical framework. We study theoretically a class of models which describes the general mechanism and allows us to distinguish its universal from system-specific features. We show that under general conditions, regardless of the details of kinetics, molecule availability encodes an averaging over past activity and feeds back multiplicatively on the system output. The kinetics of recovery from unavailability determines the effective memory kernel inside the feedback branch, giving rise to a variety of system-specific forms of adaptive response—precise or input-dependent, exponential or power-law—as special cases of the same model.
The impact of soil microorganisms on the global budget of δ
18
O in atmospheric CO
2
Authors: Wingate Lisa , Ogée Jérôme , Cuntz Matthias , Genty Bernard , Reiter Ilja , Seibt Ulli , Yakir Dan , Maseyk Kadmiel , Pendall Elise G. , Barbour Margaret M. , Mortazavi Behzad , Burlett Régis , Peylin Philippe , Miller John , Mencuccini Maurizio , Shim Jee H. , Hunt John , Grace John
Published: December 2009

Improved global estimates of terrestrial photosynthesis and respiration are critical for predicting the rate of change in atmospheric CO
2
. The oxygen isotopic composition of atmospheric CO
2
can be used to estimate these fluxes because oxygen isotopic exchange between CO
2
and water creates distinct isotopic flux signatures. The enzyme carbonic anhydrase (CA) is known to accelerate this exchange in leaves, but the possibility of CA activity in soils is commonly neglected. Here, we report widespread accelerated soil CO
2
hydration. Exchange was 10–300 times faster than the uncatalyzed rate, consistent with typical population sizes for CA-containing soil microorganisms. Including accelerated soil hydration in global model simulations modifies contributions from soil and foliage to the global CO
18
O budget and eliminates persistent discrepancies existing between model and atmospheric observations. This enhanced soil hydration also increases the differences between the isotopic signatures of photosynthesis and respiration, particularly in the tropics, increasing the precision of CO
2
gross fluxes obtained by using the δ
18
O of atmospheric CO
2
by 50%.
Systems analysis of plant cell wall degradation by the model filamentous fungus Neurospora crassa
Authors: Tian Chaoguang , Beeson William T. , Iavarone Anthony T. , Sun Jianping , Marletta Michael A. , Cate Jamie H. D. , Glass N. Louise
Published: December 2009

The filamentous fungus
Neurospora crassa
is a model laboratory organism, but in nature is commonly found growing on dead plant material, particularly grasses. Using functional genomics resources available for
N. crassa
, which include a near-full genome deletion strain set and whole genome microarrays, we undertook a system-wide analysis of plant cell wall and cellulose degradation. We identified approximately 770 genes that showed expression differences when
N. crassa
was cultured on ground
Miscanthus
stems as a sole carbon source. An overlap set of 114 genes was identified from expression analysis of
N. crassa
grown on pure cellulose. Functional annotation of up-regulated genes showed enrichment for proteins predicted to be involved in plant cell wall degradation, but also many genes encoding proteins of unknown function. As a complement to expression data, the secretome associated with
N. crassa
growth on
Miscanthus
and cellulose was determined using a shotgun proteomics approach. Over 50 proteins were identified, including 10 of the 23 predicted
N. crassa
cellulases. Strains containing deletions in genes encoding 16 proteins detected in both the microarray and mass spectrometry experiments were analyzed for phenotypic changes during growth on crystalline cellulose and for cellulase activity. While growth of some of the deletion strains on cellulose was severely diminished, other deletion strains produced higher levels of extracellular proteins that showed increased cellulase activity. These results show that the powerful tools available in
N. crassa
allow for a comprehensive system level understanding of plant cell wall degradation mechanisms used by a ubiquitous filamentous fungus.
Stochastic fate ofp53-mutant epidermal progenitor cells is tilted toward proliferation by UV B during preneoplasia
Authors: Klein Allon M. , Brash Douglas E. , Jones Philip H. , Simons Benjamin D.
Published: December 2009

UV B (UVB) radiation induces clones of cells mutant for thep53tumor suppressor gene in human and murine epidermis. Here we reanalyze large datasets that report the fate of clones in mice subjected to a course of UVB radiation, to uncover howp53mutation affects epidermal progenitor cell behavior. We show thatp53mutation leads to exponential growth of clones in UV-irradiated epidermis; this finding is also consistent with the size distribution ofp53mutant clones in human epidermis. Analysis of the tail of the size distribution further reveals that the fate of individual mutant cells is stochastic. Finally, the data suggest that ending UVB exposure results in thep53mutant cells adopting the balanced fate of wild-type cells: the loss of mutant cells is balanced by proliferation so that the population of preneoplastic cells remains constant. We conclude that preneoplastic clones do not derive from long-lived, self-renewing mutant stem cells but rather from mutant progenitors with random cell fate. It follows that ongoing, low-intensity UVB radiation will increase the number of precancerous cells dramatically compared with sporadic, higher-intensity exposure at the same cumulative dose, which may explain why nonmelanoma skin cancer incidence depends more strongly on age than on radiation dosage. Our approach may be applied to determine cell growth rates in clonally labeled material from a wide range of tissues including human samples.
FoxP3
+
regulatory T cells essentially contribute to peripheral CD8
+
T-cell tolerance induced by steady-state dendritic cells
Authors: Schildknecht Anita , Brauer Sabine , Brenner Corinne , Lahl Katharina , Schild Hansjörg , Sparwasser Tim , Probst Hans Christian , van den Broek Maries
Published: December 2009

Peripheral T-cell tolerance is thought to significantly contribute to the prevention of autoimmunity, and it has been shown that antigen-presenting steady-state dendritic cells efficiently induce peripheral tolerance. We previously showed that dendritic-cell–induced tolerance is a T-cell–intrinsic process that depends on coinhibitory molecules such as programmed death-1. Here we specifically analyze the involvement of FoxP3
+
regulatory T cells, which are known to be important for maintenance of self-tolerance. We show that antigen presentation by steady-state dendritic cells failed to induce peripheral tolerance in the absence of FoxP3
+
regulatory T cells but induced protective CD8
+
T-cell–mediated immunity instead. Regulatory T-cell–depleted mice had massively increased numbers of dendritic cells in lymph nodes. Dendritic cells isolated from mice without regulatory T cells had up-regulated costimulatory molecules and showed stronger T-cell stimulatory capacity ex vivo, suggesting that regulatory T cells contribute to peripheral tolerance by keeping the dendritic cells in an immature state. Using blocking antibodies, we demonstrate that CTLA-4 but not IL-10 is necessary for control of dendritic cells by regulatory T cells.
Functional screening identifies CRLF2 in precursor B-cell acute lymphoblastic leukemia
Authors: Yoda Akinori , Yoda Yuka , Chiaretti Sabina , Bar-Natan Michal , Mani Kartik , Rodig Scott J. , West Nathan , Xiao Yun , Brown Jennifer R. , Mitsiades Constantine , Sattler Martin , Kutok Jeffrey L. , DeAngelo Daniel J. , Wadleigh Martha , Piciocchi Alfonso , Dal Cin Paola , Bradner James E. , Griffin James D. , Anderson Kenneth C. , Stone Richard M. , Ritz Jerome , Foà Robin , Aster Jon C. , Frank David A. , Weinstock David M.
Published: December 2009

The prognosis for adults with precursor B-cell acute lymphoblastic leukemia (B-ALL) remains poor, in part from a lack of therapeutic targets. We identified the type I cytokine receptor subunit CRLF2 in a functional screen for B-ALL–derived mRNA transcripts that can substitute for IL3 signaling. We demonstrate that CRLF2 is overexpressed in approximately 15% of adult and high-risk pediatric B-ALL that lackMLL, TCF3, TEL,andBCR/ABLrearrangements, but not in B-ALL with these rearrangements or other lymphoid malignancies. CRLF2 overexpression can result from translocation with theIGHlocus or intrachromosomal deletion and is associated with poor outcome. CRLF2 overexpressing B-ALLs share a transcriptional signature that significantly overlaps with a BCR/ABL signature, and is enriched for genes involved in cytokine receptor and JAK-STAT signaling. In a subset of cases, CRLF2 harbors a Phe232Cys gain-of-function mutation that promotes constitutive dimerization and cytokine independent growth. A mutually exclusive subset harbors activating mutations in JAK2. In fact, all 22 B-ALLs with mutant JAK2 that we analyzed overexpress CRLF2, distinguishing CRLF2 as the key scaffold for mutant JAK2 signaling in B-ALL. Expression of WT CRLF2 with mutant JAK2 also promotes cytokine independent growth that, unlike CRLF2 Phe232Cys or ligand-induced signaling by WT CRLF2, is accompanied by JAK2 phosphorylation. Finally, cells dependent on CRLF2 signaling are sensitive to small molecule inhibitors of either JAKs or protein kinase C family kinases. Together, these findings implicate CRLF2 as an important factor in B-ALL with diagnostic, prognostic, and therapeutic implications.
Inhibition of bacterial disulfide bond formation by the anticoagulant warfarin
Authors: Dutton Rachel J. , Wayman April , Wei Jun-Rong , Rubin Eric J. , Beckwith Jon , Boyd Dana
Published: December 2009

Blood coagulation in humans requires the activity of vitamin K epoxide reductase (VKOR), the target of the anticoagulant warfarin (Coumadin). Bacterial homologs of VKOR were recently found to participate in a pathway leading to disulfide bond formation in secreted proteins of many bacteria. Here we show that the VKOR homolog from the bacteriumMycobacterium tuberculosis, the causative agent of human tuberculosis, is inhibited by warfarin and that warfarin-resistant mutations of mycobacterial VKOR appear in similar locations to mutations found in human patients who require higher doses of warfarin. Deletion of VKOR results in a severe growth defect in mycobacteria, and the growth ofM. tuberculosisis inhibited by warfarin. The bacterial VKOR homolog may represent a target for antibiotics and a model for genetic studies of human VKOR. We present a simple assay inEscherichia coli, based on a disulfide-sensitive β-galactosidase, which can be used to screen for stronger inhibitors of theM. tuberculosisVKOR homolog.
Sexual Trauma, Substance Abuse, and Treatment Success in a Sample of African American Women who Smoke Crack Cocaine
Authors: Young Amy M. , Boyd Carol
Published: December 2009

The purpose of this descriptive study was to examine the relationship among sexual trauma, severity of substance use, and treatment success for African American women who smoke crack cocaine. Using a convenience sample of 208 African American women with a history of crack smoking, participants were interviewed for 2 to 4 hr and asked a variety of questions about their health, relationships, sexuality, and drug use. Women with a history of sexual trauma (N = 134) reported being addicted to more substances than women who had not been sexually traumatized (N = 74), despite the fact that the two groups did not differ on the number of substances used. Differences in the self‐reported level of substance abuse was corroborated with external evidence of group differences in substance abuse severity. Women with a history of sexual trauma, compared to women without such a history, were admitted to the hospital or emergency room more often for health issues related to their substance use and were more likely to be negligent in caring for their children because of their drug use. We also found evidence to suggest that there are differences in treatment success between the two groups; women with a history of sexual trauma reported having been to substance abuse treatment programs more often than women without such a history. These findings are discussed in light of the particular treatment needs of women with a history of sexual trauma.
Cocaine, Crime, Family History of Deviance—are Psychosocial Correlates Related to these Phenomena in Male Cocaine Abusers?
Authors: Kasarabada Nagalakshmi D. , Anglin M. Douglas , Stark Elena , Paredes Alfonso
Published: December 2009

This paper examines relationships among deviant behaviors such as cocaine abuse, crime, and family history of deviance; demographics; and psychological characteristics such as aggression, sensation seeking, confidence to resist taking cocaine and risk taking tendency to use cocaine in different situations; psychiatric symptoms (e.g., depression, anxiety, obsessive‐compulsiveness, somatization, attention deficit); and social characteristics such as social adjustment. The sample consisted of men, mean age 35 years, who were veterans of the armed services. Canonical correlation analysis showed three significant canonical variates: The first indicated that verbal aggression, general sensation seeking, and a problem index for situations involving urges to use cocaine were positively related to number of times arrested and negatively related to age. The second revealed that experience seeking and problem indices for situations involving urges to use cocaine and for those involving pleasant times, were positively related to last cocaine use consumption level, total lifetime grams of cocaine used, and alcohol problems of the immediate family. The third showed that verbal aggression and a problem index for risk situations for use involving pleasant times were positively related, and experience seeking was negatively related, to number of times arrested, number of times incarcerated in the previous 30 days, age, and last cocaine use level. The implications of the associations found among these variables are discussed as they pertain to prevention, treatment, and future research.
Gender Differences in HIV Risk Behaviors among Young Adults and Adolescents Entering a Massachusetts Detoxification Center
Authors: Pugatch David , Ramratnam Mohun , Strong Larkin , Feller Alexander , Levesque Barrett , Dickinson Brian P.
Published: December 2009

We examined gender differences in HIV risk behaviors among young substance abusers 17 through 25 years of age. A voluntary and confidential survey inquiring about HIV‐related risk behaviors was administered to clients (N = 200 respondents) on intake at a drug detoxification center in Massachusetts. Female respondents were more likely than males to report having shared their needles (p < 0.01), having had sex in exchange for drugs or money (p < 0.01), sex with an HIV‐infected partner (p < 0.01), and sex with an injection‐drug user (p < 0.01). They were also more likely to report having been diagnosed with an STD (p < 0.01). Nineteen percent of females (compared to 32% of males) reported always having used condoms for vaginal sex (p = 0.08), and 16% of females compared to 35% of males reported always having used condoms for anal sex (p = 0.06). In our cohort of substance‐abusing youth, adolescent and young adult females were more likely than males to report unsafe injection‐drug use and sexual practices. The results of this study suggest that programs designed to decrease HIV risk among high‐risk substance abusers in detoxification centers should be gender specific.
Prevalence of Personality Disorders among Cocaine and Heroin Addicts
Authors: Craig Robert J.
Published: December 2009

Using the MCMI‐III, we studied rates of personality disorders among 443 inpatient drug abusers (i.e., 160 opiate addicts and 283 cocaine addicts). For both samples the disorders of antisocial (60%), passive‐aggressive (negativistic) (34%), and depressive personality disorders (32%) showed higher prevalence rates. Previous studies (N = 13) using different measures (e.g., SCID, SDIP, MCMI‐I) reported similar findings in terms of overall prevalence of specific personality disorders, although actual rates varied by population.
Drinking Cultures and the Position of Women in Nine European Countries
Authors: Allamani Allaman , Voller Fabio , Kubicka Ludek , Bloomfield Kim
Published: December 2009

Nine European countries involved in the Biomed Project “Alcohol Consumption and Alcohol Problems Among Women in European Countries”; are described in relation to sociodemographic characteristics and drinking patterns. The populations of the nine countries, especially women, have become much older during the period 1950–1995. Also, women tend to have fewer children, and at an older age, so that the percentage of the younger age groups is decreasing. If we connect this to the fact that women now are more a part of the labor force than before, we might infer that the observed decrease in gender difference in alcohol use is to be explained in relation to economic factors. In terms of drinking patterns, a broad division can be made between two wide regions: (a) the northern dry area, where beer is the leading beverage, consumed on weekends and outside mealtimes; and (b) the southern, or Mediterranean, wet area, where wine is the main beverage, usually drunk at meals. However, the dispersion in alcohol consumption found among the study countries in 1961 declined considerably by 1997. In this respect, European countries are getting more similar, so that we may consider this phenomenon a “convergence”; of alcohol drinking in Europe. More generally, changes from a more traditional drinking pattern to a novel one from another country may be due to several factors, one of which is the increasing relevance of women in the drinking context. On the treatment side, such a relevance is nowadays visible through the better availability of both health services and nonstatutory organizations to take care of women affected with alcohol‐related problems.
Alexithymia in Egyptian Substance Abusers
Authors: El Rasheed Amany Haroun
Published: December 2009

Alexithymia is thought of as a trait that predisposes to drug abuse. Moreover, it is suggested to be related to type of the substance abused, with the worst–case scenario including a worse prognosis as well as tendency to relapse or even not to seek treatment at all. To address this important subject in Egyptian patients, a sample of 200 Egyptian substance abusers was randomly selected from inpatients in the Institute of Psychiatry, Ain Shams University, Egypt. The study also included 200 group–matched controls. DSM–IV criteria were used for assessment of substance use disorders, and toxicologic urine analysis was used to confirm the substances of abuse. Toronto Alexithymia Scale (TAS)—Arabic version was used for assessment of alexithymia. It was found that alexithymia was significantly more prevalent in the substance use disorders group as compared to healthy controls. It was also found that among the substance use disorders group, alexithymics reported more polysubstance abuse, more opiate use (other than heroin TV), lower numbers of hospitalizations, lower numbers of reported relapses, and a lower tendency to relapse as a result of internal cues compared to patients without alexithymia. Statistically significant associations were also found between alexithymia and more benzodiazepine abuse and nonpersistence in treatment. The results suggest that alexithymia should be targeted in a treatment setting for substance use disorders.
Stages of Change Assessments in Alcohol Problems: Agreement across Self– and Clinician–Reports
Authors: Hodgins David C.
Published: December 2009

A number of self–report scales and “algorithms”; have been developed to measure stage of change in alcohol problems. These methods rely on client self–reports, but an alternative approach is to use clinician judgments. The purpose of this investigation was to compare approaches including a newly developed Readiness to Change Questionnaire – Clinician Version (RCQ–CV). Clients being assessed for alcohol treatment (N = 64) completed SOCRATES, the Readiness to Change Questionnaire (RCQ), a social desirability scale, and a stage of change algorithm. Clinicians completed the RCQ–CV and provided a simple assessment of stage of change. The agreement among the alternative methods was generally good with the continuous measures, including agreement between scales, between clients and clinicians, and between experienced clinicians and trainees. Agreement among categorical stage assignments was poor. The RCQ–CV shows promise as a clinical and research tool.
Internet Program Development Leading to Certification in Substance Abuse Prevention
Authors: Hagemaster Julia
Published: December 2009

The purpose of this project was to develop a multidisciplinary educational program that would provide information needed to work more efficiently in substance abuse prevention and prepare the learner for certification examination. Because prevention service providers are scattered throughout the state, country, and global community, an educational program had to be easily accessible. The solution was to develop a web–based curriculum that could be accessed anywhere in the world. One that would meet not only state requirements, but also would conform to international certification criteria. Qualitative analysis was used to categorize broad content areas of university course offerings, core functions considered vital by the state, and various educational programs in substance abuse throughout the country. As themes and subthemes emerged, clusters of essential components were retrieved and divided into four groupings. These groupings later translated into four distinct modules, each containing four to six components of study. A pilot group of 17 people were recruited throughout the state. These service providers took the web–based program over a period of 3 months and then participated in a special administration of an international certification exam. Results showed a 94% pass rate for the pilot group as compared with a national 32 %.