bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural and functional maturation of presynaptic nerve endings under the control of transsynaptic signalling
Authors: Wittenmayer Nina , Dresbach Thomas
Published: July 2012

Synapse assembly is the cellular mechanism that mediates the generation of physical con­nections between nerve cells and, thus, al­lows for the establishment of functional con­nectivity in the brain. The biogenesis of a syn­apse requires a set of highly coordinated mo­lecular events, ranging from initial forma­tion of adhesive contacts between an axon and a dendrite, followed by the recruitment and precise arrangement of synaptic organ­elles and proteins on both sides of the syn­aptic cleft, and culminating in the mainte­nance and remodelling of the exquisite archi­tecture of a differentiated, i.e. mature, synap­tic junction. Both the postsynaptic and the presynaptic compartment are thought to un­dergo stages of maturation that change and shape synaptic structure and function in a characteristic way. Recent evidence suggests that transsynaptic signalling, elicited by post­synaptic cell adhesion molecules, regulates the molecular events underlying presynap­tic maturation. Thus, synaptic cell adhesion molecules, apart from physically connecting nerve cells, emerge as coordinators of presyn­aptic and postsynaptic differentiation across the synaptic cleft.
Roger Layton's Contributions to Marketing
Authors: Wind Jerry Yoram
Published: July 2012

This article summarizes my perspective on Roger Layton's contributions to marketing, presented in the form of suggestions to young marketing scholars striving to increase the relevance, rigor and impact of their research. These guidelines include insights regarding: marketing systems and how they hold the key to economic growth (informed by Layton's early definition of the marketing system); the importance of trade flows; capitalizing on the changing geopolitical reality; attaining relevance and rigor in the field; being an early, active adopter of new concepts and methods; and challenging conventional marketing wisdom. The article draws from many seminal publications of Roger's career to illustrate these concepts, and concludes by explaining how these contributions impact the past, present and future of marketing and society.
COMPARATIVE PHOTOSYNTHESIS, WATER RELATIONS, GROWTH AND SURVIVAL RATES IN JUVENILE CRIOLLO CACAO CULTIVARS (THEOBROMA CACAO) DURING DRY AND WET SEASONS
Authors: ARAQUE O. , JAIMEZ R. E. , TEZARA W. , CORONEL I. , URICH R. , ESPINOZA W.
Published: July 2012

This study deals with the ecophysiological response of Criollo cacao cultivars to water deficit during initial establishment phase in an agroforestry system under shade of four timber species using a randomised block design. CO2 assimilation rate (A), transpiration (E) and stomatal conductance (gs), water potentials, pressure–volume curves and fluorescence measurements were studied during two dry and wet seasons. Survival rates, basal diameter and leaf concentrations of K, P and N were also determined. All cultivars exhibited 60% reduction in gs with drought, resulting in 73% decrease in A and E. Despite lower A, electron-transport rates were not significantly affected, suggesting the existence of electron sinks. Photochemical quenching is negatively affected by drought in some cultivars, whereas relative quantum yield of photosystem II and non-photochemical quenching remained the same during both the periods. Cultivars with the highest osmotic adjustment coincided with the highest survival rates, whereas growth and leaf nutrient concentrations were similar in all cultivars.
On the essential spectrum of phase-space anisotropic pseudodifferential operators
Authors: MĂNTOIU MARIUS
Published: July 2012

A phase-space anisotropic operator in=L2(ℝn) is a self-adjoint operator whose resolvent family belongs to a naturalC*-completion of the space of Hörmander symbols of order zero. Equivalently, each member of the resolvent family is norm-continuous under conjugation with the Schrödinger unitary representation of the Heisenberg group. The essential spectrum of such a phase-space anisotropic operator is the closure of the union of usual spectra of all its “phase-space asymptotic localizations”, obtained as limits over diverging ultrafilters of ℝn×ℝn-translations of the operator. The result extends previous analysis of the purely configurational anisotropic operators, for which only the behavior at infinity in ℝnwas allowed to be non-trivial.
Calcium economy in human pregnancy and lactation
Authors: Olausson Hanna , Goldberg Gail R. , Ann Laskey M. , Schoenmakers Inez , Jarjou Landing M. A. , Prentice Ann
Published: July 2012

Pregnancy and lactation are times of additional demand for Ca. Ca is transferred across the placenta for fetal skeletal mineralisation, and supplied to the mammary gland for secretion into breast milk. In theory, these additional maternal requirements could be met through mobilisation of Ca from the skeleton, increased intestinal Ca absorption efficiency, enhanced renal Ca retention or greater dietary Ca intake. The extent to which any or all of these apply, the underpinning biological mechanisms and the possible consequences for maternal and infant bone health in the short and long term are the focus of the present review. The complexities in the methodological aspects of interpreting the literature in this area are highlighted and the inter-individual variation in the response to pregnancy and lactation is reviewed. In summary, human pregnancy and lactation are associated with changes in Ca and bone metabolism that support the transfer of Ca between mother and child. The changes generally appear to be independent of maternal Ca supply in populations where Ca intakes are close to current recommendations. Evidence suggests that the processes are physiological in humans and that they provide sufficient Ca for fetal growth and breast-milk production, without relying on an increase in dietary Ca intake or compromising long-term maternal bone health. Further research is needed to determine the limitations of the maternal response to the Ca demands of pregnancy and lactation, especially among mothers with marginal and low dietary Ca intake, and to define vitamin D adequacy for reproductive women.
A multidisciplinary reconstruction of Palaeolithic nutrition that holds promise for the prevention and treatment of diseases of civilisation
Authors: Kuipers Remko S. , Joordens Josephine C. A. , Muskiet Frits A. J.
Published: July 2012

Evolutionary medicine acknowledges that many chronic degenerative diseases result from conflicts between our rapidly changing environment, our dietary habits included, and our genome, which has remained virtually unchanged since the Palaeolithic era. Reconstruction of the diet before the Agricultural and Industrial Revolutions is therefore indicated, but hampered by the ongoing debate on our ancestors' ecological niche. Arguments and their counterarguments regarding evolutionary medicine are updated and the evidence for the long-reigning hypothesis of human evolution on the arid savanna is weighed against the hypothesis that man evolved in the proximity of water. Evidence from various disciplines is discussed, including the study of palaeo-environments, comparative anatomy, biogeochemistry, archaeology, anthropology, (patho)physiology and epidemiology. Although our ancestors had much lower life expectancies, the current evidence does neither support the misconception that during the Palaeolithic there were no elderly nor that they had poor health. Rather than rejecting the possibility of ‘healthy ageing’, the default assumption should be that healthy ageing posed an evolutionary advantage for human survival. There is ample evidence that our ancestors lived in a land–water ecosystem and extracted a substantial part of their diets from both terrestrial and aquatic resources. Rather than rejecting this possibility by lack of evidence, the default assumption should be that hominins, living in coastal ecosystems with catchable aquatic resources, consumed these resources. Finally, the composition and merits of so-called ‘Palaeolithic diets’, based on different hominin niche-reconstructions, are evaluated. The benefits of these diets illustrate that it is time to incorporate this knowledge into dietary recommendations.
Externalizing problems, attention regulation, and household chaos: A longitudinal behavioral genetic study
Authors: Wang Zhe , Deater-Deckard Kirby , Petrill Stephen A. , Thompson Lee A.
Published: July 2012

Previous research documented a robust link between difficulties in self-regulation and development of externalizing problems (i.e., aggression and delinquency). In this study, we examined the longitudinal additive and interactive genetic and environmental covariation underlying this well-established link using a twin design. The sample included 131 pairs of monozygotic twins and 173 pairs of same-sex dizygotic twins who participated in three waves of annual assessment. Mothers and fathers provided reports of externalizing problems. Teacher report and observer rating were used to assess twin's attention regulation. The etiology underlying the link between externalizing problems and attention regulation shifted from a common genetic mechanism to a common environmental mechanism in the transition across middle childhood. Household chaos moderated the genetic variance of and covariance between externalizing problems and attention regulation. The genetic influence on individual differences in both externalizing problems and attention regulation was stronger in more chaotic households. However, higher levels of household chaos attenuated the genetic link between externalizing problems and attention regulation.
Toward a new understanding of legacy of early attachments for future antisocial trajectories: Evidence from two longitudinal studies
Authors: Kochanska Grazyna , Kim Sanghag
Published: July 2012

Early parent–child attachment has been extensively explored as a contributor to children's future adaptive or antisocial outcomes, but the specific developmental mechanisms remain to be fully understood. We examined long-term indirect developmental sequelae of early security in two longitudinal community samples followed from infancy to early school age: the Family Study (102 mothers, fathers, and infants) and the Parent–Child Study (112 mothers and infants). Constructs at multiple levels (child characteristics, parent–child security, parental discipline, and child antisocial outcomes) were assessed using a range of methods (extensive behavioral observations in a variety of settings, informants' ratings). Both studies supported the proposed model of infant attachment as a potent catalyst that moderates future developmental socialization trajectories, despite having few long-term main effects. In insecure dyads, a pattern of coercion emerged between children who were anger prone as toddlers and their parents, resulting in parents' increased power-assertive discipline. Power assertion in turn predicted children's rule-breaking conduct and a compromised capacity to delay in laboratory paradigms, as well as oppositional, disruptive, callous, and aggressive behavior rated by parents and teachers at early school age. This causal chain was absent in secure dyads, where child anger proneness was unrelated to power assertion, and power assertion was unrelated to antisocial outcomes. Early insecurity appeared to act as a catalyst for the parent–child dyad embarking on a mutually adversarial path toward antisocial outcomes, whereas security defused such a maladaptive dynamic. The possible mechanisms of those effects were proposed.
Do pathological gambling and obsessive-compulsive disorder overlap? a neurocognitive perspective
Authors: Hur Ji-Won , Shin Na young , Kim Sung Nyun , Jang Joon Hwan , Choi Jung-Seok , Shin Young-Chul , Kwon Jun Soo
Published: July 2012

Objective

Pathological gambling (PG) is a severe and persistent pattern of problem gambling that has been aligned with obsessive-compulsive disorder (OCD). However, no study has compared the neurocognitive profiles of individuals with PG and OCD.

Methods

We compared neurocognitive functioning, including executive function, verbal learning and memory, and visual–spatial organization and memory among 16 pathological gamblers, 31 drug-naïve OCD subjects, and 52 healthy controls.

Results

The only neurocognitive marker common to both groups was increased fragmentation errors on the Rey–Osterrieth Complex Figure Test (ROCF). The PG subjects showed increased nonperseverative error on the Wisconsin Card Sorting Test and organization difficulties in the ROCF, whereas the OCD subjects revealed longer response times on the Stroop test and retention difficulties on the immediate recall scale of the ROCF.

Conclusions

A more careful approach is required in considering whether PG is a part of the OCD spectrum, as little evidence of neurocognitive overlap between PG and OCD has been reported.
Evaluation of plant sterol intake estimated with the Northern Sweden FFQ
Authors: Klingberg Sofia , Winkvist Anna , Hallmans Göran , Johansson Ingegerd
Published: July 2012

Objective

To evaluate plant sterol intake estimated with the eighty-four-item Northern Sweden FFQ against repeated 24 h dietary recalls (24-HDR) as the reference method.

Design

Randomly recruited participants from the Västerbotten Intervention Programme (VIP) responded to an FFQ (FFQ1). Over the subsequent 12 months, ten repeated 24-HDR were carried out. After this, a second FFQ (FFQ2) was completed.

Setting

Västerbotten county, northern Sweden.

Subjects

Ninety-six men and ninety-nine women.

Results

The Pearson correlation coefficient for absolute total plant sterol intake estimated with FFQ1 and 24-HDR was 0·58 and 0·55 for the men and women, respectively. Cross-classification of participants into quartiles of absolute plant sterol intake estimated with FFQ1 and 24-HDR showed that 90 % of the men and 83 % of the women were classified into the same or an adjacent quartile. For energy-adjusted plant sterol intake, 71 % of the men and 74 % of the women were classified into the same or an adjacent quartile. The agreement for cross-classification of participants into quartiles between FFQ1 and FFQ2 was good for both absolute and energy-adjusted plant sterol intake.

Conclusions

The FFQ is able to capture absolute plant sterol intake to the same extent as other nutrients, and to rank individuals according to both their absolute and energy-adjusted plant sterol intake. The reproducibility of the FFQ was good, suggesting that the method is reliable. This makes it possible to use plant sterol data from the FFQ in large-scale studies of the association between plant sterol intake and disease.
Dayside ELF electromagnetic wave survey: A Polar statistical study of chorus and hiss
Authors: Tsurutani Bruce T. , Falkowski Barbara J. , Verkhoglyadova Olga P. , Pickett Jolene S. , Santolík Ondrej , Lakhina Gurbax S.
Published: July 2012

Statistical analyses of Polar plasma wave data are performed to determine the occurrence frequency, intensity, and Poynting direction of ∼360 Hz to ∼1.8 kHz extremely low‐frequency (ELF) electromagnetic waves (chorus, magnetosonic mode, and hiss) in the dayside sector of the magnetosphere. The study is limited to an L* range of 2 to 9 and a magnetic local time (MLT) range of 0900 to 1500, a region infrequently covered in past statistical surveys. The study was performed on 1996–1997 data, an interval near solar minimum. It is determined that in the outer region of the magnetosphere, from L* = 6 to 9, the ∼360 to ∼800 Hz waves at Polar altitudes are typically characterized by downward (toward Earth) propagation. The downgoing waves have been previously identified as chorus in Tsurutani et al. (2011). The downgoing chorus have intensities of ∼10−2 nT2, are right‐hand circularly polarized and are propagating close to parallel to the ambient magnetic field B0. The high rate of occurrence of these downward propagating waves narrows to a smaller region of L* = 6 to 7 for ∼1.2 kHz waves. In the inner region of the magnetosphere, L* = 3 to 6, the ∼360 to 800 Hz waves are characteristically oblique (to B0) and upwards propagating, away from the Earth. The upcoming waves are most likely plasmaspheric hiss and low altitude magnetospherically reflected waves. These waves are an order of magnitude less intense and less coherent than the downward propagating chorus waves. At low frequencies, ∼360 Hz, there is a region near L* = 4 to 5, where obliquely propagating waves are detected. These are most probably a mixture of obliquely propagating plasmaspheric hiss and magnetosonic waves. A detailed (case study) examination of upward propagating waves is made for one Polar pass to add context to the statistical results. The upward propagating waves are quasicoherent and slightly elliptically polarized at Polar altitudes. From this and the statistical results, we ascribe to the scenario that ∼360 to 800 Hz chorus enters the plasmasphere at low altitude entry points and propagates through the plasmasphere as semicoherent hiss, in basic agreement with the Bortnik et al. (2008, 2009a) hypothesis for the origin of some plasmaspheric hiss. However, for ∼1.2 and 1.8 kHz waves inside the nominal location of the plasmasphere, downward propagating waves have higher intensities than upward propagating or oblique waves, perhaps indicating effects associated with different source locations, different entry points and different reflection regions and/or damping/amplification. At ∼800 Hz and ∼1.2 kHz upward propagating waves with weak intensities are common in the range L* = 8–9. These may be chorus waves magnetospherically reflected to larger L*. For frequencies above ∼1.5 kHz, most wave events are low intensity and upward propagating. It is possible that sferics and power line harmonics are contributors to these signals.
Air‐sea interactions during an Arctic storm
Authors: Long Zhenxia , Perrie Will
Published: July 2012

The impacts of increased open water in the Beaufort Sea were investigated for a summer Arctic storm in 2008 using a coupled atmosphere‐ice‐ocean model. The storm originated in northern Siberia and slowly moved into the Beaufort Sea along the ice edge in late July. The maximum wind associated with the storm occurred when it was located over the open water near the Beaufort Sea coast, after it had moved over the Chukchi and Beaufort Seas. The coupled model system is shown to simulate the storm track, intensity, maximum wind speed and the ice cover well. The model simulations suggest that the lack of ice cover in the Beaufort Sea during the 2008 storm results in increased local surface wind and surface air temperature, compared to enhanced ice cover extents such as occurred in past decades. In addition, due to this increase of open water, the surface latent and sensible heat fluxes into the atmosphere are significantly increased. However, there were no significant impacts on the storm track. The expanded open water and the loss of the sea ice results in increases in the surface air temperature by as much as 8°C. Although the atmospheric warming mostly occurs in the boundary layer, there is increased atmospheric boundary turbulence and downward kinetic energy transport that reach to mid‐levels of the troposphere and beyond. These changes result in enhanced surface winds, by as much as ∼4 m/s during the 2008 storm, compared to higher ice concentration conditions (typical of past decades). The dominant sea surface temperature response to the storm occurs over open water; storm‐generated mixing in the upper ocean results in sea surface cooling of up to 2°C along the southern Beaufort Sea coastal waters. The Ekman divergence associated with the storm caused a decrease in the fresh water content in the central Beaufort Sea by about 11 cm.
The transfer of modern organic carbon by landslide activity in tropical montane ecosystems
Authors: Ramos Scharrón Carlos E. , Castellanos Edwin J. , Restrepo Carla
Published: July 2012

Geomorphic processes play an important role in the transfer and storage of carbon within steep mountainous terrain. Among these, mass wasting stands out because of its impact on above‐ and below‐ground carbon pools and its potential for releasing or sequestering carbon. A combined remote‐sensing and GIS modeling approach was used to quantify the amount and spatial redistribution of modern organic carbon mobilized by mass wasting activity in a tropical mountain setting. The study focused on a population of hundreds of shallow, translational landslides triggered by Hurricane Mitch (1998) on seven watersheds draining the southern flank of the Sierra de Las Minas mountain range (SLM) in central‐eastern Guatemala. Results illustrate that mass wasting contributed to the transfer of 43 × 104MgC, or 3%, of the pre‐event C in above‐ground vegetation and soils for an equivalent carbon flux rate of 0.08–0.33 MgC ha−1y−1, depending on whether we consider Hurricane Mitch to be a landslide‐triggering event with a 20‐year or an 80‐year recurrence interval. While 30% of this carbon was delivered to hillslopes or first‐order streams with a presumed high potential for long‐term sequestration, the remaining 70% was delivered to higher‐order streams with unknown carbon retention capabilities. Therefore, the ultimate fate of the carbon released by landsliding is very uncertain, but depending on the proportion sequestered by colluvial deposits, the recurrence interval of landslide‐triggering events, and the rate of ecosystem recuperation at the landslide failure sites, mass wasting could be either a net source or sink of carbon. In a simulated setting based on the SLM study results in which all carbon transferred by landslides from all tropical mountains of the globe is released to the atmosphere, it would represent an amount equivalent to 1%–11% of the global carbon currently being released by the burning of fossil fuels. Meanwhile, in a projected scenario where a significant proportion of the carbon transferred by landslides is retained within sedimentary deposits, sequestration rates would equal 2%–19% of the residual land sink.
Induced seismicity from fracking and carbon storage is focus of study and hearing
Authors: Showstack Randy
Published: July 2012

Hydraulic fracturing to recover shale gas does not pose a high risk for inducing felt seismic events, as the method is currently implemented, according to a 15 June report by the U.S. National Research Council (NRC). However, carbon capture and storage (CCS) has the potential to induce larger seismic events because of the large net volume of injected fluids involved in that process, according to the report. Scientists testifying at a 19 June hearing held by the U.S. Senate Committee on Energy and Natural Resources said they largely agreed with the report's findings. Neither the report nor the hearing focused on potential environmental impacts of hydraulic fracturing, which is commonly known as fracking.
Subpoena of scientists' e‐mails raises concerns
Authors: Showstack Randy
Published: July 2012

A recent court order that required the Woods Hole Oceanographic Institution (WHOI) to hand over more than 3000 confidential e‐mails to the energy company BP in May has led to concerns about the need to protect academic freedom, the deliberative scientific process, and intellectual property. Lawyers representing BP filed the subpoena in December 2011 to seek information from WHOI in relation to a lawsuit brought against BP by the U.S. government and others about damages from the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. WHOI is not a party to the lawsuit.
Honors
Authors: Anonymous
Published: July 2012

Tim Killeen has been appointed president of the Research Foundation for the State University of New York (SUNY) and SUNY vice chancellor for research, effective 9 July. Killeen has been assistant director for geosciences at the U.S. National Science Foundation since July 2008. As SUNY's research foundation president, Killeen will be responsible for the supervision and operation of the largest, most comprehensive university‐connected U.S. research foundation, according to a foundation statement. Killeen served as AGU president from 2006 to 2008 and was director of the National Center for Atmospheric Research from 2000 to 2008.
Enter AGU student contest to win free Fall Meeting registration
Authors: Smedley Kara
Published: July 2012

AGU is excited to announce its first Student Video and Student T‐shirt Design competitions. This is an opportunity for students to display their artistic sides and share their creativity and love of science with the world. Entries could highlight an aspect of Earth or space science in an educational and/or entertaining way or showcase a career path in geophysical sciences. Winners of these student‐only competitions will be awarded free registration to the 2012 Fall Meeting in San Francisco, Calif.
New images support proposal for water ice on Mercury
Authors: Balcerak Ernie
Published: July 2012

Two decades ago, radio telescope observations showed radar‐bright features in Mercury's polar regions. The radar characteristics are similar to those of the icy satellites of Jupiter and at the south polar ice cap on Mars. The radarbright spots on Mercury were therefore believed to be water ice, and images from MESSENGER provide new support for this idea. MESSENGER, the first spacecraft to orbit Mercury, has provided a view of Mercury's south polar terrain over a full Mercury day that makes it possible to identify areas in permanent shadow. Chabot et al. compared the MESSENGER images of craters in the south pole region with the distribution of radarbright features from previous radio telescope studies.
An efficient approach to imaging underground hydraulic networks
Authors: Kumar Mohi
Published: July 2012

To better locate natural resources, treat pollution, and monitor underground networks associated with geothermal plants, nuclear waste repositories, and carbon dioxide sequestration sites, scientists need to be able to accurately characterize and image fluid seepage pathways below ground. With these images, scientists can gain knowledge of soil moisture content, the porosity of geologic formations, concentrations and locations of dissolved pollutants, and the locations of oil fields or buried liquid contaminants. Creating images of the unknown hydraulic environments underfoot is a difficult task that has typically relied on broad extrapolations from characteristics and tests of rock units penetrated by sparsely positioned boreholes. Such methods, however, cannot identify small‐scale features and are very expensive to reproduce over a broad area. Further, the techniques through which information is extrapolated rely on clunky and mathematically complex statistical approaches requiring large amounts of computational power.
A physical model for metal extraction and transport in shallow magmatic systems
Authors: Huber Christian , Bachmann Olivier , Vigneresse Jean‐Louis , Dufek Josef , Parmigiani Andrea
Published: July 2012

The highest concentrations of metals (e.g., Cu, Au, Ag, Mo) in the Earth's crust are found in porphyry‐type deposits. The metals are ultimately sourced from magmas, and appear to be concentrated hundred to thousand‐fold from typical magmatic contents (ppm‐ppb) in the exsolved volatile phase. To better quantify the purging and transport of metals, we develop a physical model of volatile evolution in an incrementally built upper crustal magma reservoirs that considers (1) partitioning of metals from the melt to an exsolved volatile phase, and (2) advection of the buoyant volatile phase using a single dimensionless parameter, the Péclet number (Pe; ratio of advection rate over diffusion rate). We propose that metal extraction and segregation from magmas can occur in 3 stages with different Pe: (1) during exsolution of the magmatic volatile phase in shallow, crystal‐poor magma bodies (slow volatile advection; Pe ≪ 1), (2) during the growth of volatile channels that develop in the reservoir as crystallinity increases (Pe < 1), and (3) during advection in connected channels (rapid volatile advection, high Pe ≥ 1). For each stage, a metal enrichment factor can be calculated, allowing insight into the optimal conditions to maximize metal mass flux into the overlying hydrothermal system. The model predicts that the most efficient purging of metals occurs for magmas with intermediate volatile contents and is enhanced during late‐stage magmatic activity, as the reservoirs reach high crystallinity and are not disturbed by volcanic venting, in agreement with natural observations suggesting that ore formation post‐dates volcanic activity.
Deformation associated with the denudation of mantle‐derived rocks at the Mid‐Atlantic Ridge 13°–15°N: The role of magmatic injections and hydrothermal alteration
Authors: Picazo Suzanne , Cannat Mathilde , Delacour Adélie , Escartín Javier , Rouméjon Stéphane , Silantyev Sergei
Published: July 2012

Outcrops of deeply derived ultramafic rocks and gabbros are widespread along slow spreading ridges where they are exposed in the footwall of detachment faults. We report on the microstructural and petrological characteristics of a large number of samples from ultramafic exposures in the walls of the Mid‐Atlantic Ridge (MAR) axial valley at three distinct locations at lat. 13°N and 14°45′N. One of these locations corresponds to the footwall beneath a corrugated paleo‐fault surface. Bearing in mind that dredging and ROV sampling may not preserve the most fragile lithologies (fault gouges), this study allows us to document a sequence of deformation, and the magmatic and hydrothermal history recorded in the footwall within a few hundred meters of the axial detachment fault. At the three sampled locations, we find that tremolitic amphiboles have localized deformation in the ultramafic rocks prior to the onset of serpentinization. We interpret these tremolites as hydrothermal alteration products after evolved gabbroic rocks intruded into the peridotites. We also document two types of brittle deformation in the ultramafic rocks, which we infer could produce the sustained low magnitude seismicity recorded at ridge axis detachment faults. The first type of brittle deformation affects fresh peridotite and is associated with the injection of the evolved gabbroic melts, and the second type affects serpentinized peridotites and is associated with the injection of Si‐rich hydrothermal fluids that promote talc crystallization, leading to strain localization in thin talc shear zones. We also observed chlorite + serpentine shear zones but did not identify samples with serpentine‐only shear zones. Although the proportion of magmatic injections in the ultramafic rocks is variable, these characteristics are found at each investigated location and are therefore proposed as fundamental components of the deformation in the footwall of the detachment faults associated with denudation of mantle‐derived rocks at the MAR.
WITHDRAWN: Global CO2 Storage Potential of Self‐Sealing Marine Sedimentary Strata
Authors: Eccles Jordan K , Pratson Lincoln
Published: July 2012

Injection of CO2 below the seafloor into sedimentary strata where pressures and temperatures would trap the CO2 through “self‐sealing” gravitational and hydrate‐formation mechanisms has received little interest after analyses of a selection of deep‐sea sediment cores suggested that such storage would not likely be feasible. Attention with respect to offshore CO2 storage has since shifted to the possibility of injecting CO2 into sub‐seafloor basalt layers embedded within impermeable strata. Here we re‐examine the storage potential of self‐sealing marine sedimentary strata using a more comprehensive, global dataset of deep‐sea sediment cores, heat flow measurements, bathymetry, and sediment thickness maps. In contrast to previous reports, we find the CO2 storage potential of these strata to be abundant. We map out the worldwide distribution and thicknesses of self‐sealing marine sedimentary strata, which we estimate to have a total bulk sediment volume of 63 million cubic kilometers. Of this, roughly 1.3–2.7% may prove suitable for CO2 storage. This storage is unevenly distributed where it lies within the Exclusive Economic Zones (EEZ) of the world's largest CO2 emitting economies. The United States and India respectively release 16% and 62% of their annual CO2 emissions (or 1 Bt/y and 800 Mt/y) within 500 km of self‐sealing strata located in their EEZs, while only 6% of the annual emissions from China and the European Union (or 330 Mt/y and 250 Mt/y, respectively) occur within this distance.
Revealing forerunners on Envisat's wave mode ASAR using the Global Seismic Network
Authors: Husson R. , Ardhuin F. , Collard F. , Chapron B. , Balanche A.
Published: July 2012

Swells radiating across ocean basins are fingerprints of the large ocean storms that generated them, which are otherwise poorly observed. Here we analyze the signature of one swell event in the seismic noise recorded all around the Pacific and we show that it is a natural complement to the global coverage provided by the Synthetic Aperture Radar wave mode data from ENVISAT. In particular the seismic stations are much more sensitive to low frequency and amplitude signals than buoys and SAR, capturing swell forerunners a couple of days before they can be detected from space or in situ data. This information helps detect in the SAR measurements the presence of very long swell, with periods of 22 s in our case example, that were otherwise excluded.
Modeling and observations of the low latitude ionosphere‐plasmasphere system at long deep solar minimum
Authors: Nanan B. , Chen C. Y. , Rajesh P. K. , Liu J. Y. , Bailey G. J.
Published: July 2012

The behavior of the low latitude ionosphere‐plasmasphere system in American‐Brazilian longitudes (30°W–120°W) in three seasons at the long deep solar minimum (2006–2010) is investigated using the theoretical model SUPIM and FORMOSAT‐3/COSMIC electron density and GIM‐TEC data. The data and model reveal some new aspects primarily for the low solar EUV fluxes. The ionosphere develops as a thin layer in the morning though becomes nearly as strong as that at normal solar minimum at around diurnal maximum (14 LT). However, after sunset the ionosphere‐plasmasphere system decays rapidly to become an extremely weak cold system prior to sunrise (05 LT) when the ionosphere contracts to about 1/3rd as strong as that at normal solar minimum, with peak density only about 1.8 × 105 cm−3, half width only about 150 km, and O+/H+ transition height as low as 475 km where the ion densities are only 104 cm−3 and ion temperatures are only 600 K. The mechanical effects of the neutral wind dominate over other processes, which causes the disappearance of the well known winter anomaly in TEC and Nmax, and lowest O+/H+ transition height (∼650 km at 14 LT and 475 km at 05 LT) occurring at around ±15° magnetic latitudes where the mechanical effects optimize. In addition, the ionosphere becomes weakest about 7 months after the solar activity dipped to the lowest level in 2008.
Geodynamic models of terrane accretion: Testing the fate of island arcs, oceanic plateaus, and continental fragments in subduction zones
Authors: Tetreault J. L. , Buiter S. J. H.
Published: July 2012

Crustal growth at convergent margins can occur by the accretion of future allochthonous terranes (FATs), such as island arcs, oceanic plateaus, submarine ridges, and continental fragments. Using geodynamic numerical experiments, we demonstrate how crustal properties of FATs impact the amount of FAT crust that is accreted or subducted, the type of accretionary process, and the style of deformation on the overriding plate. Our results show that (1) accretion of crustal units occurs when there is a weak detachment layer within the FAT, (2) the depth of detachment controls the amount of crust accreted onto the overriding plate, and (3) lithospheric buoyancy does not prevent FAT subduction during constant convergence. Island arcs, oceanic plateaus, and continental fragments will completely subduct, despite having buoyant lithospheric densities, if they have rheologically strong crusts. Weak basal layers, representing pre‐existing weaknesses or detachment layers, will either lead to underplating of faulted blocks of FAT crust to the overriding plate or collision and suturing of an unbroken FAT crust. Our experiments show that the weak, ultramafic layer found at the base of island arcs and oceanic plateaus plays a significant role in terrane accretion. The different types of accretionary processes also affect deformation and uplift patterns in the overriding plate, trench migration and jumping, and the dip of the plate interface. The resulting accreted terranes produced from our numerical experiments resemble observed accreted terranes, such as the Wrangellia Terrane and Klamath Mountain terranes in the North American Cordilleran Belt.
Estimating erosional exhumation on Titan from drainage network morphology
Authors: Black Benjamin A. , Perron J. Taylor , Burr Devon M. , Drummond Sarah A.
Published: July 2012

Drainage networks on Titan, Earth, and Mars provide the only known examples of non‐volcanic fluvial activity in our solar system. The drainage networks on Titan are apparently the result of a methane‐ethane cycle similar to Earth's water cycle. The scarcity of impact craters and the uneven distribution of fluvial dissection on Titan suggest that the surface may be relatively young. The purpose of this study is to assess the importance of erosion relative to other plausible mechanisms of resurfacing such as tectonic deformation, cryovolcanism, or deposition of aerosols. We present a new method, based on a measure of drainage network shape known as the width function, to estimate cumulative erosion into an initially rough surface. We calibrate this method with a numerical landscape evolution model, and successfully test the method by applying it to river networks on Earth with different exhumation histories. To estimate erosional exhumation on Titan, we mapped fluvial networks in all Synthetic Aperture Radar swaths obtained by the Cassini spacecraft through T71. Application of our method to the most completely imaged drainage networks indicates that for two of four regions analyzed, Titan's fluvial networks have produced only minor erosional modification of the surface. For the best‐constrained region in the northern high latitudes, we find that fluvial networks reflect spatially averaged erosion of more than 0.4% but less than 9% of the initial topographic relief. This result implies either a recent, non‐fluvial resurfacing event or long‐term fluvial incision rates that are slow relative to the rate of resurfacing.
Nanoscale channels on ectomycorrhizal‐colonized chlorite: Evidence for plant‐driven fungal dissolution
Authors: Gazzè Salvatore A. , Saccone Loredana , Vala Ragnarsdottir K. , Smits Mark M. , Duran Adele L. , Leake Jonathan R. , Banwart Steven A. , McMaster Terence J.
Published: July 2012

The roots of many trees in temperate and boreal forests are sheathed with ectomycorrhizal fungi (EMF) that extend into the soil, forming intimate contact with soil minerals, from which they absorb nutrient elements required by the plants and, in return, are supported by the organic carbon photosynthesized by the trees. While EMF are strongly implicated in mineral weathering, their effects on mineral surfaces at the nanoscale are less documented. In the present study, we investigated the effects of symbiotic EMF on the topography of a chlorite mineral using atomic force microscopy. A cleaning protocol was successfully applied to remove fungal hyphae without altering the underlying mineral structure and topography. Examination of the exposed chlorite surface showed the presence of primary channels, of the order of a micron in width and up to 50 nm in depth, the morphology of which strongly indicates a fungal‐induced origin. Smaller secondary channels were observed extending from the primary channels and would appear to be involved in their enlargement. The presence of channels is the first nanoscale demonstration of the effects of fungal interaction, fuelled by plant photosynthate, on the topography of a chlorite mineral, and it provides clear evidence of the ability of EMF to enhance mineral dissolution.
Sphingosine kinase type 2 inhibition elevates circulating sphingosine 1-phosphate
Authors: Kharel Yugesh , Raje Mithun , Gao Ming , Gellett Amanda M. , Tomsig Jose L. , Lynch Kevin R. , Santos Webster L.
Published: July 2012

S1P (sphingosine 1-phosphate) is a pleiotropic lipid mediator involved in numerous cellular and physiological functions. Of note among these are cell survival and migration, as well as lymphocyte trafficking. S1P, which exerts its effects via five GPCRs (G-protein-coupled receptors) (S1P1–S1P5), is formed by the action of two SphKs (sphingosine kinases). Although SphK1 is the more intensively studied isotype, SphK2 is unique in it nuclear localization and has been reported to oppose some of the actions ascribed to SphK1. Although several scaffolds of SphK1 inhibitors have been described, there is a scarcity of selective SphK2 inhibitors that are necessary to evaluate the downstream effects of inhibition of this isotype. In the present paper we report a cationic amphiphilic small molecule that is a selective SphK2 inhibitor. In the course of characterizing this compound in wild-type and SphK-null mice, we discovered that administration of the inhibitor to wild-type mice resulted in a rapid increase in blood S1P, which is in contrast with our SphK1 inhibitor that drives circulating S1P levels down. Using a cohort of F2 hybrid mice, we confirmed, compared with wild-type mice, that circulating S1P levels were higher in SphK2-null mice and lower in SphK1-null mice. Thus both SphK1 and SphK2 inhibitors recapitulate the blood S1P levels observed in the corresponding null mice. Moreover, circulating S1P levels mirror SphK2 inhibitor levels, providing a convenient biomarker of target engagement.
Herz-OP in anderen Umständen
Authors: Hiltensperger Monika
Published: July 2012

Aortenklappenersatz einmal anders - Unverhofft herzkrank in ihrer vierten Schwangerschaft – die werdende Mutter kommt um eine lebensgefährliche Herzoperation nicht herum. Ein interdisziplinäres Team meistert die Herausforderung.
Heat transfer and friction factor of solar air heater having duct roughened artificially with discrete multiple v-ribs
Authors: Kumar Anil , Saini R. P. , Saini J. S.
Published: July 2012

In this paper, results of an experimental investigation on heat transfer and friction in a rectangular duct roughened with discrete multi v-shaped rib on one of its broad wall are presented. The discretizing of multi v-shaped rib is done by providing small symmetrical gap equal to rib height in both legs of multi v-rib. The artificially roughened duct was investigated having width to height ratio (W/H) of 12, relative width ratio (W/w) of 6, relative roughness pitch (P/e) of 10, relative roughness height (e/Dh) of 0.0433, angle of attack (α) of 60°, and relative gap distance (Gd/Lv) of 0.55. The relative gap width (g/e) was varied from 0.5 to 1.5. The heat transfer and friction factor results obtained experimentally were compared with those of smooth duct under similar experimental conditions. It is seen that there is a significant change in Nusselt number and friction factor as a result of providing discrete multi v-shape ribs. The enhancement in Nusselt number is found to be 6.32 times (that of smooth surface) for discrete multi v-shaped rib with relative gap width of 1.0. It is also found that the duct having this roughness geometry results in best thermo-hydraulic performance in comparison to other geometries under similar operating conditions.
Set-up and performance investigation of an innovative solar vehicle
Authors: Abdel Dayem Adel M.
Published: July 2012

Solar energy is a regenerative and clean source of energy. In Makkah city (21.4 °N), the solar radiation is relatively high along the year; it is more than 5 KWh/m2 a day and it is high enough to be efficiently used. On the other hand, due to high pollution and traffic in “MASHAER” region in Makkah where pilgrimage is developed, a solar vehicle can be considered as smart solution for these problems. Therefore, a gasoline engine is replaced by an electrical drive motor in an old (second hand) vehicle, cargo car. The energy required for this motor is converted from the solar energy to electric power through the installation of solar photovoltaic (PV) modules those produce energy by absorbing incoming sunlight. Then it is stored in batteries that feed the motor by needed energy. Therefore, the vehicle transmission mechanism includes electrical motor with variable speed controller that rotates the vehicle wheels by a chain drive. A simple brake system is installed to control the vehicle speed. The size of photovoltaic cells is determined based on the motor power and volt. It is found that 4 m2 PV panel area is enough to feed the car by needed power. Moreover, 6 batteries are seemed enough to move the car for about 6 h daily. The vehicle is efficiently tested carrying six passengers for about 8 h continuously working under different operating and weather conditions. Moreover, a numerical simulation was developed for the solar vehicle system to visualize the annual performance of the system. A mathematical model of the photovoltaic cells, batteries, and controller were established. Annual measured data of Makkah city is used as input parameters to the numerical simulation. The system efficiency is investigated along the year demonstrating a successful utilization of solar energy in that sector. It is found that the considered PV array can move the vehicle for less than 2 h a day in average.
The feasibility and current estimated capital costs of producing jet fuel at sea using carbon dioxide and hydrogen
Authors: Willauer Heather D. , Hardy Dennis R. , Schultz Kenneth R. , Williams Frederick W.
Published: July 2012

A comparative cost/benefit and energy balance analysis addresses the critical scientific and technical challenges that impact the economic feasibility of synthesizing up to 100 000 gal per day of jet fuel at sea using carbon dioxide (CO2) and hydrogen (H2) from the sea. Included in this analysis are the capital cost, operation and maintenance, and electrical generation cost for synthesizing jet fuel at sea using either ocean thermal energy conversion or nuclear power processes as the energy source. The results suggest that jet fuel could be produced at sea for $3 to $6/gal. Comparing these costs with current and historical prices of fuel purchased by the Department of Defense provides insight into the economic and operational benefits of a sea-based fuel synthesis process for the Navy.