bluuebunny/crossref_metadata_2025 huggingface dataset:
Internal structure of Mercury: Implications of a molten core
Authors: Riner M. A. , Bina C. R. , Robinson M. S. , Desch S. J.
Published: August 2008

Mercury is unique among the terrestrial planets for its relatively low mass (3.302 × 1023 kg) and high average density (5.427 g cm−3) that together imply an unusual iron‐rich bulk composition and thus provide an important constraint on planet formation and evolution and on compositional variations between the planets. In light of the recent discovery of a partially or fully molten core of Mercury, we model plausible interior density structures of Mercury using layered cores and the elastic properties of molten core materials. We present constraints on Mercury's decompressed density, composition, and interior structure, including elucidation of assumptions and methodology. We demonstrate the importance of molten and/or layered cores to accurately model Mercury's interior and to correctly interpret anticipated spacecraft geophysical observations. The core radius and core mass fraction will be tightly constrained by Earth‐based radar and anticipated spacecraft tracking observations, but the bulk core sulfur content and extent of the molten core are less well constrained. Finally, we discuss the implications of incorporating molten materials in modeled density structures on the hypotheses of Mercury's iron enrichment and on anticipated spacecraft results.
Mesoscale and large‐eddy simulation model studies of the Martian atmosphere in support of Phoenix
Authors: Tyler Daniel , Barnes Jeffrey R. , Skyllingstad Eric D.
Published: August 2008

In late May of 2008, the NASA/JPL Phoenix spacecraft will touch down near its targeted landing site on Mars (68.2°N, 126.6°W). Entry, descent, and landing (EDL) occurs in the late afternoon (∼1630 hours local solar time (LST)) during late northern spring (Ls ∼ 78°). Using a mesoscale and a large‐eddy simulation (LES) model, we have investigated the range of conditions that might be encountered in the lower atmosphere during EDL. High‐resolution (∼18 km) results from the Oregon State University Mars MM5 (OSU MMM5) are used to understand the hazards from the transient circulations prominent during this season. Poleward of ∼80°N these storms produce strong winds (∼35 m s−1) near the ground; however, owing to the synoptic structure of these storms, and the deep convective mixed layer equatorward of the seasonal cap boundary during EDL, our modeling suggests the spacecraft would not be in winds stronger than ∼20 m s−1 at parachute separation. The storm‐driven variability is much weaker at Phoenix latitudes than it is poleward of the seasonal cap edge (result from an extensive sensitivity study). The OSU MLES model is used to explicitly simulate the hazards of convection and atmospheric turbulence at very high resolution (100 m). This modeling suggests that an upper bound for the maximum expected horizontal‐mean atmospheric turbulent kinetic energy (TKE) is ∼12 m2 s−2, seen ∼3 km above the ground at ∼1430 hours LST. TKE amplitudes are greatest when the horizontal mean wind is large (shear production) and/or the surface albedo is low (a lower albedo enhances buoyancy production, mimicking decreased atmospheric stability after a storm advects colder air into the region). LES simulations predict deep mixed layers (∼6–7 km), ∼1.5 km deeper than the mesoscale model (∼5 km). Mesoscale modeling suggests that the actual landing site differs meteorologically from other longitudes (larger‐amplitude diurnal wind cycle), a consequence of the strong thermal circulations that are excited by the very large regional topography. The OSU MLES model was modified for this work to utilize time‐ and height‐dependent geostrophic wind forcing (constructed from OSU MMM5 results). With this forcing, the OSU MLES provides a site‐specific simulation, where the time/height variability of the horizontal mean LES wind field is in good agreement with the OSU MMM5. On the basis of some statistical analysis, we have good confidence that the “full‐spectrum” wind field is within engineering guidelines for Phoenix EDL.
Short‐period solar cycle signals in the ionosphere observed by FORMOSAT‐3/COSMIC
Authors: Liang Mao‐Chang , Li King‐Fai , Shia Run‐Lie , Yung Yuk L.
Published: August 2008

We analyze 2 years of the FORMOSAT‐3/COSMIC GPS radio occultation data to study the response of the Earth's ionosphere to the solar rotation (27‐day) induced solar flux variations. Here we report electron density variations in the ionosphere (∼100–500 km) associated with the 27‐day solar cycle. The peak‐to‐peak variation in electron density at low latitudes in the F2 region is about ∼104–105 electrons cm−3 or 20–40%, and can be as high as 60% depending on altitude, latitude, and season. The half and double periods of the 27‐day are also observed at an amplitude comparable to that of the 27‐day. The results place useful constraints for modeling chemical and dynamical processes in the ionosphere.
Pulsations of auroral kilometric radiation at Pc1 frequencies
Authors: Hanasz Jan , Schreiber Roman , Pickett Jolene , de Feraudy Hervé
Published: August 2008

Cases of AKR pulsations at frequencies 1 to 4 Hz, typical for Pc1 geomagnetic pulsations, were observed from four Cluster spacecraft. 15 events were found in years 2001–2005, with 14 occurring in a recovery phase of a strong magnetic storm. In a studied event of 22 June 2003 the AKR pulses show positive frequency drifts, corresponding to the earthward motion of AKR sources along auroral magnetic field lines. The source velocities match calculated propagation of shear Alfvén waves within the auroral cavity. In our scenario a primary cause of the AKR Pc1 pulsations can be inertial Alfvén waves converted either from electromagnetic ion cyclotron waves generated in the equatorial magnetosphere, or from electromagnetic ion cyclotron waves generated in the auroral cavity. We suggest that the parallel electric field of the earthward propagating wave can periodically produce the ‘shell’ electron distribution, which could be the free energy source of the AKR pulse emission through the electron‐cyclotron maser instability.
Relationship between accelerating seismicity and quiescence, two precursors to large earthquakes
Authors: Mignan Arnaud , Di Giovambattista Rita
Published: August 2008

The Non‐Critical Precursory Accelerating Seismicity Theory (PAST) has been proposed recently to explain the formation of accelerating seismicity (increase of the a‐value) observed before large earthquakes. In particular, it predicts that precursory accelerating seismicity should occur in the same spatiotemporal window as quiescence. In this first combined study we start by determining the spatiotemporal extent of quiescence observed prior to the 1997 Mw = 6 Umbria‐Marche earthquake, Italy, using the RTL (Region‐Time‐Length) algorithm. We then show that background events located in that spatiotemporal window form a clear acceleration, as expected by the Non‐Critical PAST. This result is a step forward in the understanding of precursory seismicity by relating two of the principal patterns that can precede large earthquakes
An improved parameterization of thermal electron heating by photoelectrons, with application to an X17 flare
Authors: Smithtro C. G. , Solomon S. C.
Published: August 2008

Global ionospheric models typically rely on parameterizations to account for heating of the plasma by photoelectrons. We compare the most commonly used parameterization to a rigorous photoelectron model and find the parameterization under‐predicts the thermal electron volume heating rate by 20–30% under nominal solar conditions. When applied to a large solar flare, the parameterized heating rate is more than an order of magnitude smaller than the peak rate calculated with the physical model. To remedy this, we develop a new parameterization of electron heating that eliminates these differences; the resulting heating rates are within 5–15% of the physical model for nominal and solar flare conditions. The new algorithm is incorporated into a 1‐D Global Average Ionosphere/Thermosphere (GAIT) model and used to investigate the response to the X17 flare of 28 October 2003. Electron temperatures calculated with the new parameterization are up to 10% higher prior to the flare, and 15% higher at the flare peak. The revised parameterization also leads to a 2% increase in neutral exospheric temperatures in the coupled model. The flare response of the global‐average thermosphere is described and found to be similar to the satellite drag results reported by Sutton et al.
Aerosol characteristics in the marine atmospheric boundary layer over the Bay of Bengal and Arabian Sea during ICARB: Spatial distribution and latitudinal and longitudinal gradients
Authors: Nair Vijayakumar S. , Babu S. Suresh , Moorthy K. Krishna
Published: August 2008

Characteristics of aerosols in the marine atmospheric boundary layer (MABL) over the Bay of Bengal (BoB), northern Indian Ocean (NIO), and Arabian Sea (AS) have been investigated using extensive measurements of the mass concentrations and mass size distributions of composite aerosols and mass concentrations of black carbon (BC) aerosols on board an oceanographic research vessel during its 2‐month‐long cruise of March–May 2006 as a part of Integrated Campaign for Aerosols, Gases, and Radiation Budget (ICARB). The data have been examined for the spatial distribution of aerosols over the oceans around India, for the north‐south (latitudinal) and east‐west (longitudinal) gradients, and to delineate the distinctiveness of these two oceanic regions with regard to aerosol properties. The results show that in general, aerosol concentrations (total and BC) are significantly higher over the BoB, compared to the AS. Over the BoB, there exists a strong latitudinal gradient with the aerosol concentrations (of total and BC) decreasing rapidly from north to south. On the other hand, over the AS the north‐south gradient was very weak and showed an opposite trend; with the concentrations, particularly of BC, increasing from north to south. In the northern BoB, due north of 13°N, BC showed strong longitudinal gradient, with the concentrations increasing from west to east; whereas due south, the longitudinal gradients were weak or insignificant. Over the southern AS, BC tended to decrease westward from the western coast of India, reached a minimum at 60°E, and increased thereafter. No longitudinal gradients were noticed in northern AS. Despite these, the BC mass fraction (FBC) was nearly constant spatially over the entire BoB, implying an almost uniformly mixed nature of BC with the composite aerosols over the BoB. In contrast, over the AS, FBC showed an increase southward along the latitude and decrease westward along the longitude. In general, the BC mass fraction was nearly 3 times higher over the BoB compared to the AS implying thereby that the aerosols over the BoB are significantly more absorbing in nature than those over the AS.
Effects of clouds on ozone profile retrievals from satellite measurements in the ultraviolet
Authors: van Diedenhoven B. , Hasekamp O. P. , Landgraf J.
Published: August 2008

We evaluated a new approach to take clouds into account in ozone profile retrievals from backscattered ultraviolet radiance measurements as performed by the Global Ozone Monitoring Experiment (GOME). In this approach ozone profiles are retrieved using cloud fractions, cloud optical thicknesses and top pressures retrieved from oxygen A‐band measurements combined with measurements between 350 nm and 390 nm. This approach (CUVO2), is compared with two commonly used approaches in ozone profile retrievals, namely to treat clouds as an effective ground surface albedo (CaA); and using effective cloud fractions and top pressures retrieved from the oxygen A‐band by assuming a cloud optical thickness of 40 (Ceff). Using simulated GOME retrievals we show that the CaA and Ceff approaches lead to significant biases in the mean ozone concentrations of up to −85% and 18% near the surface, respectively. With the CUVO2 approach these errors are reduced to below 3%. Retrievals from 233 GOME measurements using the three approaches were validated with ozonesonde measurements at 5 different locations. For most cases the results are as expected from the simulations. For scenes with strong indications for the presence of inhomogeneous clouds, all studied approaches do not correct for cloud sufficiently. The standard deviation of the differences between retrieved profiles and sonde sonde profiles is about 2.5 times larger in the troposphere than expected from the simulations, which indicates that other error sources than clouds dominate the variation in retrieval and/or validation.
Retrieving clear‐sky atmospheric parameters from SEVIRI and ABI infrared radiances
Authors: Jin Xin , Li Jun , Schmit Timothy J. , Li Jinlong , Goldberg Mitchell D. , Gurka James J.
Published: August 2008

The algorithm for the current Geostationary Operational Environmental Satellite (GOES) Sounders is adapted to produce atmospheric temperature and moisture legacy profiles from simulated infrared radiances of the Advanced Baseline Imager (ABI) on board the next generation GOES‐R. Since the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on board the Meteosat Second Generation (MSG) Meteosat‐8/9 has many of the same spectral and spatial features as ABI, it is used as proxy to test the algorithm. Because as imagers, SEVIRI and ABI do not have enough CO2 absorption spectral bands relative to the current GOES Sounders, the legacy profile algorithm for the current GOES Sounders needs to be modified. Both simulations and analysis with radiance measurements indicate that the single temperature‐sensitive infrared band (13.4 μm) of SEVIRI cannot provide enough temperature profile information. However, SEVIRI's two H2O absorption spectral bands (6.2 and 7.2 μm) are able to provide useful information on water vapor content above 700 hPa. Because of their high spatial (approximately 3 km for SEVIRI and 2 km for ABI IR bands) and high temporal (15 min full disk coverage) resolutions, SEVIRI and ABI will provide useful profile products with a quality similar to that from the current GOES Sounder prior to the availability of a hyperspectral IR sounding system in geostationary orbit.
Safe Functional Inference for Uncharacterized Viral Proteins
Authors: Loewenstein Yaniv , Linial Michal
Published: August 2008

The explosive growth in the number of sequenced genomes has created a flood of protein sequences with unknown structure and function. A routine protocol for functional inference on an input query sequence is based on a database search for homologues. Searching a query against a non-redundant database using BLAST (or more advanced methods, e.g. PSI-BLAST) suffers from several drawbacks: (i) a local alignment often dominates the results; (ii) the reported statistical score (i.e. E-value) is often misleading; (iii) incorrect annotations may be falsely propagated. Several systematic methods are commonly used to assign sequences with functions on a genomic scale. In Pfam (1) and resources alike, statistical profiles (HMMs) are built from semi-manual multiple alignments of seed homologous sequences. The profiles are then used to scan genomic sequences for additional family members. The drawbacks of this scheme are: (i) only families with a predetermined seed are considered; (ii) the query must have a detectable sequence similarity to seed sequences; (iii) attention to internal relationships among the family members or the relations to other families is lacking; (iv) family membership is often set by pre-determined thresholds.An alternative to profile or model based methods for functional inference relies on a hierarchical clustering of the protein space, as implemented in the ProtoNet approach (2). The fundamental principle is the creation of a tree that captures evolutionary relatedness among protein families. The tree construction is fully automatic, and is based only on reported BLAST similarities among clustered sequences. The tree provides protein groupings in continuous evolutionary granularities, from closely related to distant superfamilies. Clusters in the ProtoNet tree show high correspondence with homologous sequence (i.e. Pfam and InterPro), functional (i.e. E.C. classification) and structural (i.e., SCOP) families (3). A new clustering scheme (4) has provided an extensive update to the ProtoNet process, which is now based on direct clustering of all detectable sequence similarities. Herein, we use the ProtoNet resource to develop a methodology for a consistent and safe functional inference for remote families. We illustrate the success of our approach towards clusters of poorly characterized viral proteins. Viral sequences are characterized by a rapid evolutionary rate which drives viral families to be even more remote (sequence-similarity-wise). Thus, functional inference for viral families is apparently an unsolved task. Despite this inherent difficulty, the new ProtoNet tree scaffold reliably captures weak evolutionary connections for viral families, which were previously overlooked. We take advantage of this, and propose new functional assignments for viral protein families.
The Food Safety Hazard Guidebook
Authors: Lawley Richard , Curtis Laurie , Davis Judy
Published: August 2008

Food safety is important and consumers have a right to expect that those who supply the food that they buy have taken every care to manufacture products that will do them no harm. Those with a responsibility for the regulation of the global food industry recognise this principle and legislate accordingly and the business of managing and regulating the safety of the food supply chain has come a long way in the last 25 years or so. Prompted by the emergence of new food safety hazards, such as the bacterial pathogens Listeria monocytogenes and E. coli O157, powerful new techniques for evaluating and managing the risks presented by these threats have been developed. For example, hazard analysis critical control point, or HACCP, has now become the food safety management system of choice worldwide. Although the food safety management tools are now widely available, they are still virtually useless unless they are supported by adequate and accurate information. HACCP does not work unless its practitioners have access to enough data and scientific knowledge to enable them to understand hazards and how to control them effectively. The Food Safety Hazard Guidebook is an attempt to address the problem of accessing the available information by distilling the key facts about a wide range of individual food safety hazards into a single text. The result is a guidebook, rather than an encyclopaedia, which acts as a portal for the immense and ever expanding body of scientific knowledge that exists for food safety. It is an easy-to-use information resource for anyone with a professional interest in the safety of the food supply. The book is easy to navigate and presents concise and carefully researched factual information on a wide range of biological and chemical hazards in a clear format that is designed to support risk analysis exercises and HACCP studies. It covers a broad range of established and emerging food safety hazards and includes details of authoritative sources of further information (many web-based) for those seeking to examine a topic in greater depth. The section on food allergens is a particularly valuable component of the book, the chapters on fish toxins are also useful and unusual in a book of this kind and bacterial pathogens are comprehensively covered. One of the most important features of the book is the wide scope of the content and the highly structured format designed to help the reader find information quickly. Other key benefits to the reader are: -The wide range of biological and chemical hazards covered in a single book -Written specifically with food industry professionals in mind -Easy to navigate and accessible for the non-expert -Clear and concise presentation of factual information presented in a format that lends itself to use in risk assessment exercises -Inclusion of references and web links to reliable sources of further information on each chapter -specifically designed for practical use by a professional readership.
Femtosecond laser-induced electronic plasma at metal surface
Authors: Chen Zhaoyang , Mao Samuel S.
Published: August 2008

We develop a theoretical analysis to model plasma initiation at the early stage of femtosecond laser irradiation of metal surfaces. The calculation reveals that there is a threshold intensity for the formation of a microscale electronic plasma at the laser-irradidated metal surface. As the full width at half maximum of a laser pulse increases from 15to200fs, the plasma formation threshold decreases by merely about 20%. The dependence of the threshold intensity on laser pulse width can be attributed to laser-induced surface electron emission, in particular due to the effect of photoelectric effect.
Microfluidic Devices for Flow-Through Supported Palladium Catalysis on Porous Organic Monolith
Authors: Canty Allan J. , Deverell Jeremy A. , Gömann Anissa , Guijt Rosanne M. , Rodemann Thomas , Smith Jason A.
Published: August 2008

Flow-through microreactors are described, constructed of fused silica capillaries with an internal diameter of 100 μm and glass microchips with a channel dimension of 150 μm and involving the in situ UV-initiated synthesis of a poly(glycidyl methacrylate-co-ethylene dimethacrylate) porous polymer monolith. The monolith is a continuous material covalently bonded to the capillary or chip walls, with good flow-through properties. Epoxide ring-opening through amine attack by 5-amino-1,10-phenanthroline and coordination to dichloropalladium(ii) allows use of the microreactors for Suzuki–Miyaura catalysis. The long-term stability and reliability of the robust chip microreactor is demonstrated by operation for 96 h, exhibiting undiminished reactivity, and very low leaching of palladium.
Rearing two New Zealand fur seal (Arctocephalus forsteri) pups to weaning
Authors: Dowell Sacha A. , Boren Laura J. , Negro Sandra S. , Muller Chris G. , Caudron Abigail K. , Gemmell Neil J.
Published: August 2008

The rearing of two pups to weaning is a rare occurrence in pinnipeds and in many cases it remains unknown whether it is a result of twinning or fostering. This study followed two cases where female New Zealand fur seals (Arctocephalus forsteri) raised two pups, at a colony in Kaikoura, New Zealand. Maternal attendance behaviour was observed, mass and condition of the pups were measured and genetic samples were collected to assess relatedness. In one case, the female gave birth to twins, while the other case was found to be fostering of a second pup. In both cases, the filial pups of each female exhibited significantly lower mass, condition and growth rates than the colony average. The twins’ mother reared both pups to weaning and did not appear to spend a different amount of time ashore compared with single-pup mothers. The current study confirms both fostering and twinning in New Zealand fur seals, with the potential for successfully raising the pups to weaning, despite their well developed recognition system and the energy costs involved.
The characteristics of squirrel glider (Petaurus norfolcensis) den trees in subtropical Australia
Authors: Beyer Georgia L. , Goldingay Ross L. , Sharpe David J.
Published: August 2008

Effective management of tree-hollow-dependent wildlife requires a sound knowledge of the characteristics of the trees used for shelter or breeding. We used radio-tracking to identify the den trees of squirrel gliders (Petaurus norfolcensis) in south-east Queensland (Qld) and north-east New South Wales (NSW). Squirrel gliders used dead trees as well as 13 species of living tree for dens across the two locations. Dead trees accounted for a large percentage of dens (54% of 48 dens in Qld, and 50% of 18 dens in NSW) despite comprising only 3–10% of the forest (trees >20 cm diameter at breast height (dbh)) at each location. This preference is largely due to dead trees being more likely to contain hollows, accounting for 26–44% of available hollow-bearing trees. Mean den tree size (dbh) was 48.9 ± 2.4 cm in Qld and 62.8 ± 5.6 cm in NSW. Den entrance height averaged 6.8 ± 1.2 m in Qld and 11.9 ± 1.3 m in NSW. Fissures in the trunk and holes in branches were the most common of six hollow types used. At one location branch end hollows were ignored relative to their availability. Den entrances varied in size (2.5–12 cm wide) but most were ≤5 cm in diameter. Entrance size of hollows appears to be the hollow attribute of most importance to squirrel gliders. Monitoring of these den trees over several years revealed the collapse of three dead den trees at each location, which is equivalent to an annual loss of 3% of den trees. Further research is needed to determine whether this will lead to a future shortage of den trees.
Structures of invisible, excited protein states by relaxation dispersion NMR spectroscopy
Authors: Vallurupalli Pramodh , Hansen D. Flemming , Kay Lewis E.
Published: August 2008

Molecular function is often predicated on excursions between ground states and higher energy conformers that can play important roles in ligand binding, molecular recognition, enzyme catalysis, and protein folding. The tools of structural biology enable a detailed characterization of ground state structure and dynamics; however, studies of excited state conformations are more difficult because they are of low population and may exist only transiently. Here we describe an approach based on relaxation dispersion NMR spectroscopy in which structures of invisible, excited states are obtained from chemical shifts and residual anisotropic magnetic interactions. To establish the utility of the approach, we studied an exchanging protein (Abp1p SH3 domain)–ligand (Ark1p peptide) system, in which the peptide is added in only small amounts so that the ligand-bound form is invisible. From a collection of
15
N,
1
HN,
13
C
α
, and
13
CO chemical shifts, along with
1
HN-
15
N,
1
H
α
-
13
C
α
, and
1
HN-
13
CO residual dipolar couplings and
13
CO residual chemical shift anisotropies, all pertaining to the invisible, bound conformer, the structure of the bound state is determined. The structure so obtained is cross-validated by comparison with
1
HN-
15
N residual dipolar couplings recorded in a second alignment medium. The methodology described opens up the possibility for detailed structural studies of invisible protein conformers at a level of detail that has heretofore been restricted to applications involving visible ground states of proteins.
Accumulation of mutants in “aging” bacterial colonies is due to growth under selection, not stress-induced mutagenesis
Authors: Wrande Marie , Roth John R. , Hughes Diarmaid
Published: August 2008

Several bacterial systems show behavior interpreted as evidence for stress-induced mutagenesis (adaptive mutation), a postulated process by which nongrowing cells temporarily increase their general mutation rate. Theoretical considerations suggest that periodic stress-induced general mutagenesis would not be advantageous in the long term, due to the high cost of deleterious mutations. Alternative explanations have been tested for very few of the systems used as evidence for stress-induced mutation. In one prominent system, mutants resistant to rifampicin (Rif
R
;
rpoB
; RNA polymerase) accumulate in cell populations that “age” on solid medium with little net growth. Mutant accumulation was initially attributed to stress-induced general mutagenesis in nongrowing cells. Evidence is presented that these Rif
R
mutants accumulate because they grow faster than parent cells during the aging period. Direct tests revealed no increase in the frequency of other mutant types during the aging period.
A
Drosophila
model for Angelman syndrome
Authors: Wu Yaning , Bolduc Francois V. , Bell Kimberly , Tully Tim , Fang Yanshan , Sehgal Amita , Fischer Janice A.
Published: August 2008

Angelman syndrome is a neurological disorder whose symptoms include severe mental retardation, loss of motor coordination, and sleep disturbances. The disease is caused by a loss of function of
UBE3A
, which encodes a HECT-domain ubiquitin ligase. Here, we generate a
Drosophila
model for the disease. The results of several experiments show that the functions of human
UBE3A
and its fly counterpart,
dube3a
, are similar. First, expression of Dube3a is enriched in the
Drosophila
nervous system, including mushroom bodies, the seat of learning and memory. Second, we have generated
dube3a
null mutants, and they appear normal externally, but display abnormal locomotive behavior and circadian rhythms, and defective long-term memory. Third, flies that overexpress Dube3a in the nervous system also display locomotion defects, dependent on the ubiquitin ligase activity. Finally, missense mutations in
UBE3A
alleles of Angelman syndrome patients alter amino acid residues conserved in the fly protein, and when introduced into
dube3a
, behave as loss-of-function mutations. The simplest model for Angelman syndrome is that in the absence of UBE3A, particular substrates fail to be ubiquitinated and proteasomally degraded, accumulate in the brain, and interfere with brain function. We have generated flies useful for genetic screens to identify Dube3a substrates. These flies overexpress Dube3a in the eye or wing and display morphological abnormalities, dependent on the critical catalytic cysteine. We conclude that
dube3a
mutants are a valid model for Angelman syndrome, with great potential for identifying the elusive UBE3A substrates relevant to the disease.
The CD83 reporter mouse elucidates the activity of the CD83 promoter in B, T, and dendritic cell populationsin vivo
Authors: Lechmann Matthias , Shuman Naomi , Wakeham Andrew , Mak Tak W.
Published: August 2008

CD83 is the major surface marker identifying mature dendritic cells (DCs). In this study, we report the generation of reporter mice expressing EGFP under the control of the CD83 promoter. We have used these mice to characterize CD83 expression by various immune system cell types bothin vivoandex vivoand under steady-state conditions and in response to stimulation with a Toll-like receptor (TLR) ligand. With those mice we could provein vivothat the CD83 promoter is highly active in all DCs and B cells in lymphoid organs. Interestingly, this promoter activity in B cells mainly depended on the stage of development, is up-regulated in the late pre-B cell stage, and was maintained on a high level in all peripheral B cells. We also confirmed that CD83 in those cells is mainly intracellular but is up-regulated after TLR stimulation. Otherwise, CD83 promoter activity in T cells seemed to depend on stimulation and could be found mainly in CD4+CD25+and CD8+CD25+T cells and in CD4+and CD8+memory cells. In addition, we identified the murine homologues of the human CD83 splice variants. In contrast to those in human, those extremely rare short transcripts were never found without the expression of the highly dominant full-length form. So, the murine CD83 surface expression is mainly regulated posttranslationallyin vivo. Our CD83 reporter mice represent a useful mouse model for monitoring the activation status and migration of DCs and lymphocytes under various conditions, and our results provide much needed clarification of the true nature of CD83 promoter activity.
BAG‐1 expression in normal endometrium, endometrial hyperplasia and endometrial cancer
Authors: SONG JAE YUN , KIM JI WON , LEE JAE KWAN , LEE NAK WOO , YEOM BOM WOO , KIM SUN HAENG , LEE KYU WAN
Published: August 2008

Background. BAG‐1 (Bcl‐2‐associated athanogene 1) is a BCL‐2 binding anti‐apoptotic protein that may play a role in carcinogenesis. The purpose of this study is to compare the expression rate of BAG‐1 in normal endometrium, endometrial hyperplasia and endometrial cancer, and further to determine a correlation between BAG‐1 expression and clinicopathological parameters, and overall survival. Methods. Tissue samples from 43 patients who were diagnosed with endometrial cancer, tissue samples from 20 patients with endometrial hyperplasia and tissue samples from 20 normal patients were included in the study. Immunohistochemical analyses were performed using a polyclonal anti‐BAG‐1 antibody from paraffin‐embedded blocks. Results. Cytoplasmic BAG‐1 expression of the normal endometrium, endometrial hyperplasia and endometrial cancer samples was 4/20 (20%), 3/20 (15%) and 27/43 (62%), respectively. Nuclear BAG‐1 expression was 17/20 (85%), 12/20 (60%) and 16/43 (37%), respectively. Cytoplasmic BAG‐1 expression correlated with cancer grade (p = 0.02). The mean survival of patients with positive/negative cytoplasmic BAG‐1 expression and nuclear BAG‐1 expression was 49.4/45.4 and 54.0/41.1 months, respectively, but there was no statistical difference for survival (log‐rank p = 0.31, p = 0.55). Conclusion. Cytoplasmic BAG‐1 is more frequently expressed in endometrial cancer tissues than in normal and endometrial hyperplasia tissues (p = 0.0007), and its expression correlates with cancer grade. Nuclear BAG‐1 is more frequently expressed in the normal endometrium and hyperplasia tissues than in endometrial cancer tissues (p = 0.002). Neither cytoplasmic nor nuclear BAG‐1 expression is associated with survival.
The Islamization and Ethnogenesis of the Fereydani Georgians
Authors: Rezvani Babak
Published: August 2008

Fereydani Georgians are the only Georgian-speaking ethnic group in Iran. Despite being all that is left of the once vast and important Georgian-speaking community in Iran, this ethnic group is still largely unknown, both inside and outside Iran. There is a general consensus that Georgians have played a pivotal role in Iran's history since the seventeenth century. Despite this, the Fereydani Georgians are also still relatively unknown within Iran itself. Also in Georgia there is some (popular) knowledge about them. Nevertheless, even this knowledge is rudimentary and is plagued by a large number of misconceptions. The Fereydani Georgians are virtually unknown outside Iran and Georgia.
Humor, Abstraction, and Disbelief
Authors: Hoicka Elena , Jutsum Sarah , Gattis Merideth
Published: August 2008

We investigated humor as a context for learning about abstraction and disbelief. More specifically, we investigated how parents support humor understanding during book sharing with their toddlers. In Study 1, a corpus analysis revealed that in books aimed at 1‐to 2‐year‐olds, humor is found more often than other forms of doing the wrong thing including mistakes, pretense, lying, false beliefs, and metaphors. In Study 2, 20 parents read a book containing humorous and non‐humorous pages to their 19‐to 26‐month‐olds. Parents used a significantly higher percentage of high abstraction extra‐textual utterances (ETUs) when reading the humorous pages. In Study 3, 41 parents read either a humorous or non‐humorous book to their 18‐to 24‐month‐olds. Parents reading the humorous book made significantly more ETUs coded for a specific form of high abstraction: those encouraging disbelief of prior utterances. Sharing humorous books thus increases toddlers' exposure to high abstraction and belief‐based language.
The Wisdom of Collaborative Network Organizations: Capturing the Value of Networked Individuals
1
Authors: Dutton William H.
Published: August 2008

Digital networks, particularly the Internet, are used widely to search for information and to share expertise and knowledge between peers. Such collaborative problem solving and co‐creation of services and products go beyond traditional organizational boundaries and geographical constraints, raising major questions about how to manage networked individuals and capture the value of their activities. This paper conveys the findings of a series of case studies designed to explore these questions. This led to a framework for categorizing the networks which suggests the management and performance of ‘collaborative network organizations’ will be contingent on the ways in which they are used to reconfigure information and communication flows for the distributed sharing, generation or co‐creation of content.
Drugs, alcohol and pregnant women—changing characteristics of women engaging with a specialist perinatal outreach addictions service
Authors: MAYET SORAYA , GROSHKOVA TEODORA , MORGAN LOUISE , MacCORMACK TRACEY , STRANG JOHN
Published: August 2008

Pregnant substance misusers present an increased risk to themselves and the unborn child. The aim of this study was to investigate changes in the characteristics of women referred to a specialist perinatal addictions outreach service (1989–1991 versus 2002–2005). A cross‐sectional audit of health records was conducted. Information was gathered for each woman who contacted the service (2002–2005). Data were compared to an earlier study in the same locality (1989–1991). A total of 167 pregnant substance‐using women were referred between 2002 and 2005, of whom 126 made contact. The mean age was 30.2 years at 20.8 weeks' fetal gestation, with 76% not in addictions treatment, 32% from black or minority ethnic (BME) communities, 49% polysubstance users and 29% homeless. The primary substance used was illicit heroin (38%), followed by cocaine (24%). Compared to 1989–1991, there were significantly more pregnant women presenting at an older age, later gestation, with increased polysubstance use and a higher percentage of women from BME communities. This service was able to access vulnerable substance‐abusing women with an altered pattern of substance use compared to over 10 years previously. However, improvements are needed for engaging all referred women and accessing women at an earlier gestation.
A COMPARATIVE PERSPECTIVE ON INTERGENERATIONAL SUPPORT
Authors: Kalmijn Matthijs , Saraceno Chiara
Published: August 2008

It has often been argued that Southern European countries are more familialistic in their culture than Western and Northern European countries. In this paper, we examine this notion by testing the hypothesis that adult children are more responsive to the needs of their elderly parents in countries with more familialistic attitudes. To test this hypothesis, we analyse the Survey of Health, Ageing and Retirement in Europe (SHARE). We focus on three indicators of need: (a) the partner status of the parent, (b) the health status of the parent, and (c) the education of the parent. Using Heckman probit models, we examine the effects of these variables on whether or not the parent receives instrumental support from children, thereby controlling for whether or not children live independently from their parents. We estimate effects of need on support and we compare these effects across 10 European countries, using both graphic devices and a multilevel probit model where individuals are nested in countries. We find significant cross-level interactions of need variables and the degree of familialism in a country. Our analyses, thereby provide more positive evidence for the hypothesis than earlier studies, which have focused largely on comparing aggregate levels of support among countries.
Short Article: Why do we slow down after an error? Mechanisms underlying the effects of posterror slowing
Authors: Jentzsch Ines , Dudschig Carolin
Published: August 2008

People often become slower in their performance after committing an error, which is usually explained by strategic control adjustments towards a more conservative response threshold. The present study tested an alternative hypothesis for explaining posterror slowing in terms of behavioural interferences resulting from error monitoring by manipulating stimulus contrast and categorization difficulty in a choice reaction time task. The response–stimulus interval (RSI) was either short or long, using a between-subject (Experiment 1) and a within-subject design (Experiment 2). Posterror slowing was larger and posterror accuracy lower in short than in long RSI situations. Effects of stimulus contrast disappeared in posterror trials when RSI was short. At long RSIs, stimulus contrast was additive with posterror slowing. The results support the idea that at least two mechanisms contribute to posterror slowing: a capacity-limited error-monitoring process with the strongest influence at short RSIs and a criterion adjustment mechanism at longer RSIs.
Short Article: Assessing the Automaticity of Moral Processing: Efficient Coding of Moral Information During Narrative Comprehension
Authors: Murphy Fionnuala C. , Wilde Gemma , Ogden Neil , Barnard Philip J. , Calder Andrew J.
Published: August 2008

A long-standing theoretical debate concerns the involvement of principled reasoning versus relatively automatic intuitive-emotional processing in moral cognition. To address this, we investigated whether the mental models formed during story comprehension contain a moral dimension and whether this process is affected by cognitive load. A total of 72 participants read stories about fictional characters in a range of moral situations, such as a husband being tempted to commit adultery. Each story concluded with a “moral” or “immoral” target sentence. Consistent with a framework of efficient extraction of moral information, participants took significantly longer to read immoral than moral target sentences. Moreover, the magnitude of this effect was not compromised by cognitive load. Our findings provide evidence of efficient coding of moral dimensions during narrative comprehension and demonstrate that this process does not require cognitively intense forms of principled reasoning.
G Protein-coupled Receptor-promoted Trafficking of Gβ1γ2Leads to AKT Activation at Endosomes via a Mechanism Mediated by Gβ1γ2-Rab11a Interaction
Authors: García-Regalado Alejandro , Guzmán-Hernández María Luisa , Ramírez-Rangel Iliana , Robles-Molina Evelyn , Balla Tamas , Vázquez-Prado José , Reyes-Cruz Guadalupe
Published: August 2008

G-protein coupled receptors activate heterotrimeric G proteins at the plasma membrane in which most of their effectors are intrinsically located or transiently associated as the external signal is being transduced. This paradigm has been extended to the intracellular compartments by studies in yeast showing that trafficking of Gα activates phosphatidylinositol 3-kinase (PI3K) at endosomal compartments, suggesting that vesicle trafficking regulates potential actions of Gα and possibly Gβγ at the level of endosomes. Here, we show that Gβγ interacts with Rab11a and that the two proteins colocalize at early and recycling endosomes in response to activation of lysophosphatidic acid (LPA) receptors. This agonist-dependent association of Gβγ to Rab11a-positive endosomes contributes to the recruitment of PI3K and phosphorylation of AKT at this intracellular compartment. These events are sensitive to the expression of a dominant-negative Rab11a mutant or treatment with wortmannin, suggesting that Rab11a-dependent Gβγ trafficking promotes the activation of the PI3K/AKT signaling pathway associated with endosomal compartments. In addition, RNA interference-mediated Rab11a depletion, or expression of a dominant-negative Rab11a mutant attenuated LPA-dependent cell survival and proliferation, suggesting that endosomal activation of the PI3K/AKT signaling pathway in response to Gβγ trafficking, via its interaction with Rab11, is a relevant step in the mechanism controlling these fundamental events.
DNA Topoisomerase II Is a Determinant of the Tensile Properties of Yeast Centromeric Chromatin and the Tension Checkpoint
Authors: Warsi Tariq H. , Navarro Michelle S. , Bachant Jeff
Published: August 2008

Centromeric (CEN) chromatin is placed under mechanical tension and stretches as kinetochores biorient on the mitotic spindle. This deformation could conceivably provide a readout of biorientation to error correction mechanisms that monitor kinetochore–spindle interactions, but whether CEN chromatin acts in a tensiometer capacity is unresolved. Here, we report observations linking yeast Topoisomerase II (Top2) to both CEN mechanics and assessment of interkinetochore tension. First, in top2-4 and sumoylation-resistant top2-SNM mutants CEN chromatin stretches extensively during biorientation, resulting in increased sister kinetochore separation and preanaphase spindle extension. Our data indicate increased CEN stretching corresponds with alterations to CEN topology induced in response to tension. Second, Top2 potentiates aspects of the tension checkpoint. Mutations affecting the Mtw1 kinetochore protein activate Ipl1 kinase to detach kinetochores and induce spindle checkpoint arrest. In mtw1top2-4 and mtw1top2-SNM mutants, however, kinetochores are resistant to detachment and checkpoint arrest is attenuated. For top2-SNM cells, CEN stretching and checkpoint attenuation occur even in the absence of catenation linking sister chromatids. In sum, Top2 seems to play a novel role in CEN compaction that is distinct from decatenation. Perturbations to this function may allow weakened kinetochores to stretch CENs in a manner that mimics tension or evades Ipl1 surveillance.
The structure of SgrAI bound to DNA; recognition of an 8 base pair target
Authors: Dunten Pete W. , Little Elizabeth J. , Gregory Mark T. , Manohar Veena M. , Dalton Michael , Hough David , Bitinaite Jurate , Horton Nancy C.
Published: August 2008

The three-dimensional X-ray crystal structure of the ‘rare cutting’ type II restriction endonuclease SgrAI bound to cognate DNA is presented. SgrAI forms a dimer bound to one duplex of DNA. Two Ca2+ bind in the enzyme active site, with one ion at the interface between the protein and DNA, and the second bound distal from the DNA. These sites are differentially occupied by Mn2+, with strong binding at the protein–DNA interface, but only partial occupancy of the distal site. The DNA remains uncleaved in the structures from crystals grown in the presence of either divalent cation. The structure of the dimer of SgrAI is similar to those of Cfr10I, Bse634I and NgoMIV, however no tetrameric structure of SgrAI is observed. DNA contacts to the central CCGG base pairs of the SgrAI canonical target sequence (CR|CCGGYG, | marks the site of cleavage) are found to be very similar to those in the NgoMIV/DNA structure (target sequence G|CCGGC). Specificity at the degenerate YR base pairs of the SgrAI sequence may occur via indirect readout using DNA distortion. Recognition of the outer GC base pairs occurs through a single contact to the G from an arginine side chain located in a region unique to SgrAI.