bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative analysis of seabed mixing and intertidal zone discharge in coastal aquifers
Authors: Maji Roudrajit , Smith Leslie
Published: November 2009

Contaminant loading from an inland source zone to the nearshore marine environment is examined using a saturated‐unsaturated simulation model which incorporates both the influence of the growth and the extinction of the seepage face in the intertidal zone and the inclusion of hydromechanical stress coupling due to tidal loading. The system analyzed represents a site where an unconfined aquifer extends offshore with a broad intertidal zone. The volumetric discharge of groundwater in the intertidal zone dominates the discharge occurring beyond the low‐tide line. For most of the cases examined, within the intertidal zone, the recirculated saline component of the discharge is greater than the freshwater component. The majority of the contaminant mass exits through the seepage face located above the instantaneous tide line. The peak contaminant loading rate occurs around the time of the falling midtide. At low tide, the contaminant loading rate is more than 2 orders of magnitude lower than the peak rates, even though groundwater discharge rates are highest as low tide is approached. Sensitivity studies indicate that the relative proportion of recirculated intertidal zone discharge to fresh intertidal zone discharge is most sensitive to the magnitude of the freshwater flux, the spatial variation of the outflow across the intertidal zone as influenced by anisotropy in hydraulic conductivity, and tidal pumping as influenced by specific storage. Dilution of contaminant concentrations due to mixing with seawater beneath the sediment‐water interface is represented in terms of a dilution factor, defined relative to the onshore source concentration. For our base case, the dilution factor for the contaminant concentration averaged over one tidal cycle at the high‐tide, midtide, and low‐tide lines was 1.3, 3.9, and 560, respectively. The key factors determining contaminant dilution at the sediment interface are location within the intertidal zone and the vertical extent of the contaminant plume as it enters the intertidal zone.
North Atlantic production of nitrous oxide in the context of changing atmospheric levels
Authors: Freing A. , Wallace D. W. R. , Tanhua T. , Walter S. , Bange H. W.
Published: November 2009

We use transit time distributions calculated from tracer data together with in situ measurements of N2O to estimate the concentration of biologically produced N2O ([N2O]xs) and N2O production rates in the central North Atlantic Ocean. Our approach to estimation of N2O production rates integrates the effects of potentially varying production and decomposition mechanisms along the transport path of a water mass. We find that previously used approaches overestimate the oceanic equilibrium N2O concentrations by 8–13% and thus underestimate the strength of N2O sources in large parts of the water column. Thus the quantitative characteristics of the [N2O]xs/AOU relationship used as an indicator of nitrification are distorted. We developed a new parameterization of N2O production during nitrification depending linearly on AOU and exponentially on temperature and depth, which can be applied to calculate N2O production due to nitrification in the entire ocean including oxygen minimum zones.
Glacial to postglacial transformation of organic input pathways in Arctic Ocean basins
Authors: Yunker Mark B. , Macdonald Robie W. , Snowdon Lloyd R.
Published: November 2009

The Arctic Ocean is undergoing rapid loss in ice cover with yet unknown consequences for the cycling of organic material. Here we examine persistent terrigenous (land‐based) alkane and polycyclic aromatic hydrocarbons with vascular plant, combustion, and petrogenic sources in seven cores collected from all major basins of the Arctic Ocean for insight as to how organic cycling at the Last Glacial Maximum compares to the present day. We find only modest changes between the glacial and postglacial sediments for atmospherically transported hydrocarbon biomarkers, demonstrating that glacial sea ice was not a barrier to atmospheric inputs. In stark contrast, particle‐associated biomarkers were captured strongly at basin edges during the glacial period and much more evenly transported across basins during the postglacial period. Evidently the capture of organic matter shifted from the slopes to the shelves as the latter flooded during the Holocene, and the Transpolar Drift and Beaufort Gyre evolved from minor carriers of plant detritus from the glacial ocean margins to major modern transporters of shelf sediment to the basins. This suggests that changes in organic transport currently accompanying the loss of sea ice are likely to be very different from those that occurred at the end of the last glacial period.
Atmospheric pCO2 sensitivity to the solubility pump: Role of the low‐latitude ocean
Authors: DeVries T. , Primeau F.
Published: November 2009

Previous research has shown that the atmospheric pCO2 sensitivity to changes in low‐latitude sea‐surface chemistry (“low‐latitude sensitivity”) depends on both the volume of the ocean ventilated from low latitudes and on the degree of air‐sea disequilibrium at high latitudes. However, it is not clear which effect is more important. In this paper we present a diagnostic framework for quantifying the relative importance of low‐latitude ventilation versus high‐latitude air‐sea disequilibrium in determining the low‐latitude sensitivity of ocean carbon cycle models. The diagnostic uses a Green function that partitions the ocean's carbon inventory on the basis of whether the carbon last interacted with the atmosphere in the low latitudes or in the high latitudes. The diagnostic is applied to a simple 3‐box model, a box model with a ventilated thermocline, and a suite of OGCM runs meant to capture a range of possible ocean circulations for present and last‐glacial‐maximum conditions. The diagnostic shows unambiguously that the OGCM has a greater low‐latitude sensitivity than the box models because of the greater amount of water ventilated from low latitudes in the OGCM. However, when applied to the suite of OGCM runs, the diagnostic also reveals that the effect of high‐latitude air‐sea disequilibrium can sometimes dominate the effect of low‐latitude ventilation and is highly sensitive to the state of the ocean circulation. In particular, the magnitude of the high‐latitude disequilibrium effect correlates strongly with the strength of the Atlantic meridional overturning circulation and the volume of water ventilated from northern high latitudes.
Effect of the fluorescent indicator calcein on Mg and Sr incorporation into foraminiferal calcite
Authors: Dissard Delphine , Nehrke Gernot , Reichart Gert Jan , Nouet Julius , Bijma Jelle
Published: November 2009

The development of particular analytical methods like laser ablation–inductively coupled plasma–mass spectrometry (LA‐ICP‐MS) renders it possible to determine the composition of a single chamber of foraminifers tests. This is crucial in the investigation of benthic foraminifers since the growth of new chambers under laboratory conditions does not face the difficulties associated with experiments involving reproduction. The addition of chambers can be recognized by the incorporation of the fluorescent dye calcein. When added to the culture medium, previously formed chambers are not affected, and calcein is only incorporated in calcite that is formed in its presence. However, it has never been verified whether calcein affects the element incorporation into foraminiferal calcite. In order to investigate and quantify possible effects, specimens of the benthic foraminifer Ammonia tepida were cultured in the presence and absence of calcein (15°C, salinity 33), and Mg and Sr in newly formed chambers were analyzed with LA‐ICP‐MS. Magnesium concentrations of cross sections and longitudinal sections of foraminifera from the same experiment were also analyzed by electron microprobe measurements. Additionally, the impact of calcein on Mg and Sr incorporation in inorganically precipitated calcium carbonate crystals was quantified. Results show that presence of calcein does not impact the incorporation of Mg and Sr into biologically and inorganically precipitated calcium carbonate.
Magnetohydrodynamic simulation of the interaction between two interplanetary magnetic clouds and its consequent geoeffectiveness: 2. Oblique collision
Authors: Xiong Ming , Zheng Huinan , Wang Shui
Published: November 2009

The numerical studies of the interplanetary coupling between multiple magnetic clouds (MCs) are continued by a 2.5‐dimensional ideal magnetohydrodynamic (MHD) model in the heliospheric meridional plane. The interplanetary direct collision (DC)/oblique collision (OC) between both MCs results from their same/different initial propagation orientations. Here the OC is explored in contrast to the results of the DC. Both the slow MC1 and fast MC2 are consequently injected from the different heliospheric latitudes to form a compound stream during the interplanetary propagation. The MC1 and MC2 undergo contrary deflections during the process of oblique collision. Their deflection angles of ∣δθ1∣ and ∣δθ2∣ continuously increase until both MC‐driven shock fronts are merged into a stronger compound one. The ∣δθ1∣, ∣δθ2∣, and total deflection angle Δθ (Δθ = ∣δθ1∣ + ∣δθ2∣) reach their corresponding maxima when the initial eruptions of both MCs are at an appropriate angular difference. Moreover, with the increase of MC2's initial speed, the OC becomes more intense, and the enhancement of δθ1 is much more sensitive to δθ2. The ∣δθ1∣ is generally far less than the ∣δθ2∣, and the unusual case of ∣δθ1∣ ≃ ∣δθ2∣ only occurs for an extremely violent OC. But because of the elasticity of the MC body to buffer the collision, this deflection would gradually approach an asymptotic degree. As a result, the opposite deflection between the two MCs, together with the inherent magnetic elasticity of each MC, could efficiently relieve the external compression for the OC in the interplanetary space. Such a deflection effect for the OC case is essentially absent for the DC case. Therefore, besides the magnetic elasticity, magnetic helicity, and reciprocal compression, the deflection due to the OC should be considered for the evolution and ensuing geoeffectiveness of interplanetary interaction among successive coronal mass ejections.
Formation of a plasma depletion shell in the equatorial ionosphere
Authors: Kil Hyosub , Heelis Roderick A. , Paxton Larry J. , Oh Seung‐Jun
Published: November 2009

An accurate description of the irregularity region defined by a plasma bubble is critically important in understanding the dynamics of the region and its effects on radio scintillation. Here we describe a plasma depletion region as a “depletion shell” and show how two‐dimensional optical images from space can be used to define the shape of the depletion shell. Our simple model calculation demonstrates that the space‐based optical observation can detect the plasma‐depleted magnetic flux tubes only near the F‐peak height. The backward C‐shape in bubble images from optical observations is the trace of the plasma depletion shell near the F‐peak height. The westward tilt of bubbles at the magnetic equator can also be explained by this shell structure. The in situ measurement of the ion velocity at night in the topside shows the decrease of the eastward plasma drift with an increase of latitude. The formation of the plasma depletion shell is consistent with the latitudinal/altitudinal shear in the zonal plasma flow.
Energetic particle evidence for magnetic filaments in Jupiter's magnetotail
Authors: Hill Matthew E. , Haggerty Dennis K. , McNutt Ralph L. , Paranicas Christopher P.
Published: November 2009

Jupiter's immense magnetotail was uniquely traversed and observed in situ to 2562 Jovian radii (RJ = 71,492 km) for the first time by the Pluto‐bound New Horizons spacecraft during the first half of 2007. We show evidence that energetic ions with sulfur‐rich composition traceable to Io's volcanism originated 150 ± 40 RJ antisunward of the planet and were recurrently released and funneled by the magnetic field down the magnetotail. Ions detected at New Horizons by the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument showed unmistakable signatures of velocity dispersion. We performed a survey of the unambiguous dispersion events observed by PEPSSI and provide a quantitative description of each event's dispersion characteristics. Energetic ions are sensitive probes of the magnetic field structure in the magnetotail; so, for a case study of one of the most interesting events, beginning on day of year 118, 28 April 2007, we are also able to estimate small‐scale features of the magnetotail. Our observations (which include energies above ∼2 keV/nuc and total energies below ∼1 MeV), combined with straightforward simulations of particle flow, are consistent with narrow spatial structures, or filaments, on the order of 5 RJ wide in the ∼400 RJ wide > 9000 RJ long magnetotail; the Solar Wind Around Pluto plasma instrument measurements show coherent structures on a much larger scale (∼500 RJ) in the same region.
Love wave dispersion in central North America determined using absolute displacement seismograms from high‐rate GPS
Authors: Davis James P. , Smalley Robert
Published: November 2009

We use seismic array processing of high‐rate GPS (HRGPS) displacement time series from the Great, 2004,Mw9+, Sumatra‐Andaman earthquake recorded at over 90 nonuniformly distributed HRGPS stations in central North America to determine the fundamental Love wave phase velocity dispersion curve there. These measurements were performed using frequency domain beam forming, which we show reduces the effects of GPS multipath and common mode noise on the measurement of surface wave phase velocity and azimuth. Our HRGPS based results for surface wave phase velocity agree well with those obtained from 28 broadband seismometers between periods of 20 to 300 s. By separating waves based on their apparent velocity, beam forming supports the simple model for relative displacement HRGPS time series as being the difference between the reference and kinematic station's absolute displacements. Beam forming also demonstrates that for differential GPS processing the infinite apparent velocity beam of an array is composed of the sum of common mode noise and the reference station's absolute displacements, multipath and noise. We show the infinite apparent velocity beam, which we call the generalized spatial filter, is similar to the spatial filter commonly used to remove common mode noise from HRGPS seismograms and can be used to produce absolute displacement time series for the kinematic stations with reduced common mode noise. Beam forming also suggests a filtering method, complimentary to sidereal filtering, to produce GPS multipath reduced HRGPS time series.
Influence of ocean circulation on phytoplankton biomass distribution in the Balearic Sea: Study based on Sea‐viewing Wide Field‐of‐view Sensor and altimetry satellite data
Authors: Jordi Antoni , Basterretxea Gotzon , Anglès Sílvia
Published: November 2009

This paper analyzes the spatial time series of surface chlorophyll (Chl) from the Sea‐viewing Wide Field‐of‐view Sensor and sea level anomaly (SLA) from altimetry satellite data from July 2002 to December 2007 in order to characterize the influence of the regional circulation on the phytoplankton biomass in the Balearic Sea. Correlations between Chl and SLA at seasonal and interannual time scales were examined using the singular value decomposition (SVD) method of the cross‐covariance matrix between Chl and SLA. Both seasonal cycles are negatively correlated in the whole basin, indicating that the nutrient availability in the surface layer for biological uptake is associated with the changes in the water column stratification. The coupled patterns, by applying the SVD method to Chl and SLA deviations from their seasonal cycles, identify three distinct biological responses to the circulation. The first pattern (explaining 70% of the covariance between Chl and SLA) indicates Chl enhancements around the Balearic Islands related to the Balearic current reinforced by the Northern current. The second pattern (12% of the covariance) shows that the peninsular coast is rather isolated from the regional surface circulation and its behavior is determined by the Ebro river discharges and land runoff. The third pattern (9%) represents higher Chl values along the peninsular slope and lower Chl around the Balearic Islands linked to the Northern current crossing the Ibiza channel without feeding the Baleric current.
Remotely sensed river surface features compared with modeling and in situ measurements
Authors: Plant William J. , Branch Ruth , Chatham Gene , Chickadel C. Chris , Hayes Ken , Hayworth Bronwyn , Horner‐Devine Alexander , Jessup Andrew , Fong Derek A. , Fringer Oliver B. , Giddings Sarah N. , Monismith Stephen , Wang Bing
Published: November 2009

Images of river surface features that reflect the bathymetry and flow in the river have been obtained using remote sensing at microwave, visible, and infrared frequencies. The experiments were conducted at Jetty Island near the mouth of the Snohomish River at Everett, Washington, where complex tidal flow occurs over a varied bathymetry, which was measured as part of these experiments. An X band (9.36 GHz) Doppler radar was operated from the river bank and produced images of normalized radar cross sections and radial surface velocities every 20 min over many tidal cycles. The visible and infrared instruments were flown in an airplane. All of these techniques showed surface evidence of frontal features, flow over a sill, and flow conditioned by a deep hole. These features were modeled numerically, and the model results correspond well to the remote observations. In situ measurements made near the hole showed that changes in measured velocities correlate well with the occurrence of the features in the images. In addition to tidal phase, the occurrence of these features in the imagery depends on tidal range. The surface roughness observed in the imagery appears to be generated by the bathymetry and flow themselves rather than by the modulation of wind waves.
Changes in total ocean mass derived from GRACE, GPS, and ocean modeling with weekly resolution
Authors: Rietbroek R. , Brunnabend S.‐E. , Dahle C. , Kusche J. , Flechtner F. , Schröter J. , Timmermann R.
Published: November 2009

We derive changes in ocean bottom pressure (OBP) and ocean mass by combining modeled ocean bottom pressure, weekly GRACE‐derived models of gravity change, and large‐scale deformation patterns sensed by a global network of GPS stations in a joint least squares inversion. The weekly combination allows a consistent estimation of geocenter motion, loading mass harmonics up to degree 30, and a spatially uniform mass correction term, which serves as a correction for forcing of the ocean model. We provide maps and time series of ocean mass and bottom pressure variations. Furthermore, we discuss the estimated geocenter motion and the estimated model correction. Our results indicate that the total ocean mass change is predominantly annual, with a maximum amplitude corresponding to 7.4 mm in October, which is in line with earlier work. The mean ocean bottom pressure (i.e., ocean plus atmospheric mass) shows an annual amplitude of 8.7 mm and is shifted forward by about 1.5 months. In addition, the solution exhibits typical autocorrelation times of about 2 weeks. A comparison with in situ bottom pressure time series in the southern Indian Ocean shows a good agreement, with correlations of 0.7–0.8. Based on these comparisons, we see that our results monitor realistic submonthly variations, which are strongest at high latitudes. The addition of GRACE data in the inversion is found to improve these high‐latitude variations and enables better separability of the geocenter motion from other unknowns. Increasing the OBP model error from 3 cm to 4.8 cm affects mainly the higher‐degree coefficients.
An aerosol boomerang: Rapid around‐the‐world transport of smoke from the December 2006 Australian forest fires observed from space
Authors: Dirksen Ruud J. , Folkert Boersma K. , de Laat Jos , Stammes Piet , van der Werf Guido R. , Val Martin Maria , Kelder Hennie M.
Published: November 2009

We investigate rapid around‐the‐world transport of a smoke aerosol plume released by intense forest fires in southeastern Australia in December 2006. During the first half of December 2006, southeastern Australia suffered from severe drought and exceptionally high temperatures. On 14 December 2006, a passing cold front in combination with the intense heat from the fires causing pyro‐convective lofting, injected a large mass of aerosol particles into the jet stream. We track the resulting aerosol plume using Aerosol Absorbing Index (AAI) observations from the Ozone Monitoring Instrument (OMI) and find that it circumnavigated the world in 12 days. Using observations from OMI and the CALIOP (Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation) spaceborne lidar, we show that the plume resided in the high troposphere at different stages of its evolution. In absence of CALIOP data, we explored OMI O2‐O2 pressures to obtain information on the aerosol plume height. Detailed radiative transfer calculations suggest that the current OMI O2‐O2 retrievals contain useful information on the altitude of the aerosol plume under specific conditions (high AAI, no clouds below). The observed two‐dimensional evolution of the smoke aerosol plume and the vertical distribution of the plume detected by CALIOP is matched by simulations with the TM4 chemistry transport model for an injection height of 248 hPa (∼10 km). Injection heights at the surface and at 540 hPa (∼5 km) resulted in simulated vertical distributions that were 2–3 km too low relative to CALIOP observations and showed less agreement with the AAI patterns. The high injection altitude of 10 km mimics the effect of pyro‐convective lofting as the additional buoyancy from the intense fires is not accounted for in the model. TM4 simulations with an inert and a water‐soluble tracer reproduce the observed dilution of the plume and show that the latter gives the best agreement with the observations, suggesting that the ultimate removal of the aerosol particles is by scavenging. To our knowledge, this is the first detailed study of around‐the‐world long‐range transport of forest fire emissions in the extratropical Southern Hemisphere.
Dynamics and mass balance of Taylor Glacier, Antarctica: 3. State of mass balance
Authors: Kavanaugh J. L. , Cuffey K. M. , Morse D. L. , Bliss A. K. , Aciego S. M.
Published: November 2009

Taylor Glacier flows from the East Antarctic Ice Sheet and terminates in the McMurdo Dry Valleys, where it has left a geomorphologic record of past incursions. Here we use new data on the flow, thickness, and surface balance of Taylor Glacier to calculate ice fluxes and assess the current state of mass balance. Overall, the glacier is close to a state of zero net balance, and has largely adjusted to reduced snowfall on the Taylor Dome source region in the mid Holocene. One region of the upper ablation zone appears to be losing mass. Evidence from ice surface morphology and stable isotope profiles suggests that this mass loss is a long‐term phenomenon, hence probably a lingering response to the earlier drying of Taylor Dome. Our data give a general indication of the size of ablation or accumulation changes needed for ice to advance far into Taylor Valley, as occurred 70 to 130 ka ago.
Home is where the bench is
Authors: Wolinsky Howard
Published: November 2009

Scientists have always travelled to share knowledge and ideas, or to flee from tyranny and oppressive regimes. Yet, the past decade has seen many more setting out for distant shores: Howard Wolinsky explores their motivations.
Boycott everything
Authors: Jacobs Howy
Published: November 2009

This month, Howy Jacobs draws lessons from the Vietnam War and Soviet Russia to answer the question: is an academic boycott ever relevant and appropriate?
Academic freedom in Israel and Palestine
Authors: Rose Steven
Published: November 2009

Steven Rose makes his case for an academic boycott of Israel in response to the situation of Palestinian scientists.
Effect of IPP5, a novel inhibitor of PP1, on apoptosis and the underlying mechanisms involved
Authors: Zeng Qiyan , Huang Yu , Zeng Linjie , Lan Xiuwan , Huang Yongqi , He Shujia , Zhang Hong
Published: November 2009

Genes encoding apoptosis‐inducing proteins are postulated to be candidate tumour suppressors. The identification of such proteins may benefit the early diagnosis and therapy of tumours. In the present study, we characterized the function of a novel human BMSC (bone marrow stromal cell)‐derived protein {IPP5 [inhibitor‐5 of PP1 (protein phosphatase 1)]} by large‐scale random sequencing of a human BMSC cDNA library. hIPP5 (human IPP5) cDNA encodes a protein of 116 amino acid residues, which shares high homology with human PPI‐1 (inhibitor‐1 of PP1). The effect of IPP5 on apoptosis and the underlying molecular mechanisms were investigated by overexpression of IPP5 in HeLa cells, a human cervical carcinoma cell line. Our results showed that overexpression of active mutant IPP5 inhibited anchorage‐dependent growth and induced apoptosis in HeLa cells, which may be attributed to the up‐regulation of p21waf/cip1 (a 21 kDa cell‐cycle regulatory protein), p53 and Bcl‐2‐antagonist/killer, and down‐regulation of Bcl‐2 and Bcl‐XL. We also showed that the expression of active mutant IPP5 in HeLa cells was further enhanced on TNF (tumour necrosis factor) treatment and overexpression of active mutant IPP5 sensitized HeLa cells to TNF‐induced JNK (c‐Jun N‐terminal kinase) and p38 activation as well as TNF‐mediated apoptosis. Thus overexpression of active mutant IPP5 may increase cell susceptibility to TNF‐induced apoptosis by the activation of p38 and JNK pathways. In addition, IPP5 active mutant could interact with PP1α as demonstrated by the co‐precipitation assay.
Development of cationic colloidal silica‐coated magnetic nanospheres for highly selective and rapid enrichment of plasma membrane fractions for proteomics analysis
Authors: Li Xuanwen , Jia Xueen , Xie Chunliang , Lin Yong , Cao Rui , He Quanze , Chen Ping , Wang Xianchun , Liang Songping
Published: November 2009

PM (plasma membrane) proteins play critical roles in many biological processes and are often used as molecular targets for drug discovery. In PM proteome research, fast and highly selective methods for PM preparation are highly desirable for efficient PM protein identification. In the present study, an improved PM isolation technique involving coating intact cells with synthesized cationic silica‐coated magnetic nanospheres was developed and applied to the proteomic analysis of the PM from human erythroleukaemia K562 cells. Western blotting characterization and protein identification of the prepared PM indicated that the PM enrichment method using the prepared magnetic nanospheres is a fast and inexpensive strategy with high specificity. Our results demonstrate the potential of these cationic silica‐coated magnetic nanospheres for high‐throughput identification of PM proteins from cells.
In vitro small intestinal epithelial cell growth on a nanocomposite polycaprolactone scaffold
Authors: Gupta Ashish , Vara Dina S. , Punshon Geoffrey , Sales Kevin M. , Winslet Marc C. , Seifalian Alexander M.
Published: November 2009

Tissue engineering of the small intestine remains experimental despite worldwide attempts to develop a functional substitute for short bowel syndrome. Most published studies have reported predominant use of PLLA (poly‐L‐lactide acid)/PGA (polyglycolic acid) copolymer as the scaffold material, and studies have been limited by in vivo experiments. This lack of progress has inspired a fresh perspective and provoked further investigation and development in this field of tissue engineering. In the present paper, we exploit a relatively new nanocomposite of POSS (polyhedral oligomeric silsesquioxane) and PCL [poly(caprolactone‐urea)urethane] as a material to develop porous scaffolds using a solvent casting/particulate leaching technique to fabricate porous scaffolds in different pore sizes and porosities. Scaffolds were characterized for pore morphology and porosity using scanning electron microscopy and micro‐computed tomography. Rat intestinal epithelial cells were then seeded on to the polymer scaffolds for an in vitro study of cell compatibility and proliferation, which was assessed by Alamar Blue™ and lactate dehydrogenase assays performed for 21 days post‐seeding. The results obtained demonstrate that POSS–PCL nanocomposite was produced as a macroporous scaffold with porosity over the range of 40–80% and pore size over the range of 150–250 μm. This scaffold was shown to support epithelial cell proliferation and growth. In conclusion, as a further step in investigating small intestinal tissue engineering, the nanocomposite employed in this study may prove to be a useful alternative to poly(lactic‐co‐glycolic acid) in the future.
Brd2 disruption in mice causes severe obesity without Type 2 diabetes
Authors: Wang Fangnian , Liu Hongsheng , Blanton Wanda P. , Belkina Anna , Lebrasseur Nathan K. , Denis Gerald V.
Published: November 2009

Certain human subpopulations are metabolically healthy but obese, or metabolically obese but normal weight; such mutations uncouple obesity from glucose intolerance, revealing pathways implicated in Type 2 diabetes. Current searches for relevant genes consume significant effort. We have reported previously a novel double bromodomain protein called Brd2, which is a transcriptional co-activator/co-repressor with SWI/SNF (switch mating type/sucrose non-fermenting)-like functions that regulates chromatin. In the present study, we show that wholebody disruption of Brd2, an unusual MHC gene, causes lifelong severe obesity in mice with pancreatic islet expansion, hyperinsulinaemia, hepatosteatosis and elevated pro-inflammatory cytokines, but, surprisingly, enhanced glucose tolerance, elevated adiponectin, increased weight of brown adipose tissue, heat production and expression of mitochondrial uncoupling proteins in brown adipose tissue, reduced macrophage infiltration in white adipose tissue, and lowered blood glucose, leading to an improved metabolic profile and avoiding eventual Type 2 diabetes. Brd2 is highly expressed in pancreatic β-cells, where it normally inhibits β-cell mitosis and insulin transcription. In 3T3-L1 pre-adipocytes, Brd2 normally co-represses PPAR-γ (peroxisome-proliferator-activated receptor-γ) and inhibits adipogenesis. Brd2 knockdown protects 3T3-L1 adipocytes from TNF-α (tumour necrosis factor-α)-induced insulin resistance, thereby decoupling inflammation from insulin resistance. Thus hypomorphic Brd2 shifts energy balance toward storage without causing glucose intolerance and may provide a novel model for obese metabolically healthy humans.
The oxyanion hole ofPseudomonas fluorescensmannitol 2-dehydrogenase: a novel structural motif for electrostatic stabilization in alcohol dehydrogenase active sites
Authors: Klimacek Mario , Nidetzky Bernd
Published: November 2009

The side chains of Asn191 and Asn300 constitute a characteristic structural motif of the active site of Pseudomonas fluorescens mannitol 2-dehydrogenase that lacks precedent in known alcohol dehydrogenases and resembles the canonical oxyanion binding pocket of serine proteases. We have used steady-state and transient kinetic studies of the effects of varied pH and deuterium isotopic substitutions in substrates and solvent on the enzymatic rates to delineate catalytic consequences resulting from individual and combined replacements of the two asparagine residues by alanine. The rate constants for the overall hydride transfer to and from C-2 of mannitol, which were estimated as ~ 5×102 s−1 and ~ 1.5×103 s−1 in the wild-type enzyme respectively, were selectively slowed, between 540- and 2700-fold, in single-site mannitol 2-dehydrogenase mutants. These effects were additive in the corresponding doubly mutated enzyme, suggesting independent functioning of the two asparagine residues in catalysis. Partial disruption of the oxyanion hole in single-site mutants caused an upshift, by ≥1.2 pH units, in the kinetic pK of the catalytic acid-base Lys295 in the enzyme–NAD+–mannitol complex. The oxyanion hole of mannitol 2-dehydrogenase is suggested to drive a precatalytic conformational equilibrium at the ternary complex level in which the reactive group of the substrate is ‘activated’ for chemical conversion through its precise alignment with the unprotonated side chain of Lys295 (mannitol oxidation) and C=O bond polarization by the carboxamide moieties of Asn191 and Asn300 (fructose reduction). In the subsequent hydride transfer step, the two asparagine residues provide ~ 40 kJ/mol of electrostatic stabilization.
CTRP3/cartducin is induced by transforming growth factor‐β1 and promotes vascular smooth muscle cell proliferation
Authors: Maeda Takashi , Wakisaka Satoshi
Published: November 2009

CTRP3 (C1q and tumour necrosis factor‐related protein 3)/cartducin, a novel serum protein, is a member of the CTRP superfamily. Although the CTRP3/cartducin gene is markedly up‐regulated in rat carotid arteries after balloon injury, little is known about its biological roles in arterial remodelling and neointima formation in injured blood vessels. We have investigated the mechanisms underlying CTRP3/cartducin up‐regulation and the in vitro effects of CTRP3/cartducin on vascular smooth muscle cells. CTRP3/cartducin expression in cultured p53LMAC01 vascular smooth muscle cells was induced by TGF‐β1 (transforming growth factor‐β1), but not by bFGF (basic fibroblast growth factor) or PDGF‐BB (platelet‐derived growth factor‐BB). Exogenous CTRP3/cartducin promoted the proliferation of p53LMAC01 cells in a dose‐dependent manner via ERK1/2 (extracellular signal‐regulated kinase 1/2)‐ and MAPK (p38 mitogen‐activated protein kinase)‐signalling pathways. In contrast, CTRP3/cartducin exhibited no effect on the migration of p53LMAC01 cells. Taken together, the results of the present study demonstrate a novel biological role of CTRP3/cartducin in promoting vascular smooth muscle cell proliferation in blood vessel walls after injury.
Transforming growth factor‐β1 modulates metalloproteinase‐2 and ‐9, nitric oxide, RhoA and α‐smooth muscle actin expression in colon adenocarcinoma cells
Authors: Paduch Roman , Kandefer‐Szerszeń Martyna , Szuster‐Ciesielska Agnieszka , Plewka Krzysztof
Published: November 2009

Colon carcinoma invasiveness is a process involving cell–cell and cell–matrix alterations, local proteolysis of the ECM (extracellular matrix) or changes in cytokine and growth factor levels. In order to evaluate the role of TGF‐β1 (transforming growth factor‐β1) and small G protein RhoA in tumour progression, the influence of TGF‐β1 treatment or RhoA‐associated kinase inhibitor on the production of NO (nitric oxide) and MMP‐2 and MMP‐9 (metalloproteinases‐2 and ‐9) was analysed in three human colon adenocarcinoma cell lines (HT29, LS180, SW948) representing different stages of tumour development. All the tested cell lines produced low amounts of MMP‐2 and MMP‐9. rhTGF‐β1 and the synthetic Rho kinase inhibitor (Y‐27632) decreased MMP‐2 secretion by colon cancer cells, especially in the most advanced stage of colon cancer. rhTGF‐β1 decreased NO secretion by cells, while Y‐27632 had no effect on it. Immunoblotting with anti‐RhoA antibodies followed by densitometry revealed that RhoA levels were slightly increased after incubation of colon carcinoma cells (SW948) with rhTGF‐β1. rhTGF‐β1 induced α‐smooth muscle actin (α‐SMA) expression, especially in high Duke's grade of colon cancer, while Y‐27632 blocked it. Summing up, in colon carcinoma cells, TGF‐β1 and RhoA protein may regulate tumour invasiveness measured as MMP, NO and α‐SMA expression or assayed using motility data and may be a good target for cancer therapy.
Monolayer formation of human osteoblastic cells on vertically aligned multiwalled carbon nanotube scaffolds
Authors: Lobo Anderson O. , Antunes Erica F. , Palma Mariana BS , Pacheco‐Soares Cristina , Trava‐Airoldi Vladimir J. , Corat Evaldo J.
Published: November 2009

Monolayer formation of SaOS‐2 (human osteoblast‐like cells) was observed on VACNT (vertically aligned multiwalled carbon nanotubes) scaffolds without purification or functionalization. The VACNT were produced by a microwave plasma chemical vapour deposition on titanium surfaces with nickel or iron as catalyst. Cell viability and morphology studies were evaluated by LDH (lactate dehydrogenase) release assay and SEM (scanning electron microscopy), respectively. The non‐toxicity and the flat spreading with monolayer formation of the SaOs‐2 on VACNT scaffolds surface indicate that they can be used for biomedical applications.
Association of p73 G4C14‐to‐A4T14 polymorphism at exon 2 with the response of human lung adenocarcinoma cell lines to chemotherapy
Authors: Liu Kaishan , Jiang Lucen , Zhou Xulong
Published: November 2009

In order to assess the effect of p73 gene polymorphism G4C14‐A4T14 on cisplatin‐based chemosensitivity of human lung adenocarcinoma cell lines, we examined the differences in biological character and drug sensitivity affected by cisplatin between human lung adenocarcinoma cell lines A549 and P15. The allelic expression ofp73 in A549 and P15 was studied by Sty I polymorphism analysis. MTT [3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide] assay was used to analyse the response of these two cell lines to cisplatin. The changes in the biological behaviour of the cells were observed by colony formation assay. The drug‐induced apoptosis of cells was measured by Hoechst and TUNEL techniques. Homozygous allelic expression was demonstrated in the two cell lines. AT/AT genotype appeared in A549, GC/GC genotype was detected in P15. Although the colony formation number decreased with an increasing cisplatin dose (P<0.05), there was no significant difference in colony‐formation rate in these two cell lines (P>0.05). MTT assay also determined that the 50% inhibitory concentration (IC50) for A549 and P15 was 8.9 and 11.6 μmol/l, respectively; the IC50 value did not differ significantly between A549 and P15 (P>0.05). The cell apoptosis induced by cisplatin was demonstrated in both A549 and P15. P73 G4C14‐A4T14 polymorphisms at exon 2 existed in human NSCLC (non‐small‐cell lung cancer) cell lines. Our data in vitro suggest that p73 G4C14‐A4T14 polymorphism has no significant relationship to the cisplatin‐based chemosensitivity in human lung adenocarcinoma.
Early-life nutrition influences thymic growth in male mice that may be related to the regulation of longevity
Authors: Chen Jian-Hua , Tarry-Adkins Jane L. , Heppolette Chantal A.A. , Palmer Donald B. , Ozanne Susan E.
Published: November 2009

Nutrition and growth rate during early life can influence later health and lifespan. We have demonstrated previously that low birthweight, resulting from maternal protein restriction during pregnancy followed by catch-up growth in rodents, was associated with shortened lifespan, whereas protein restriction and slow growth during lactation increased lifespan. The underlying mechanisms by which these differences arise are unknown. In the present study, we report that maternal protein restriction in mice influences thymic growth in early adult life. Offspring of dams fed a low-protein diet during lactation (PLP offspring) had significant thymic growth from 21 days to 12 weeks of age, whereas this was not observed in control mice or offspring of dams fed a low-protein diet during pregnancy (recuperated offspring). PCNA (proliferating-cell nuclear antigen) and SIRT1 (silent information regulator 1) protein levels at 21 days of age were significantly higher in the thymus from both PLP mice (P<0.001 and P<0.05 respectively) and recuperated mice (P<0.001 and P<0.01 respectively) compared with controls. At 12 weeks, PLP mice maintained a higher SIRT1 level, whereas PCNA was decreased in the thymus from recuperated offspring. This suggests that mitotic activity was initially enhanced in the thymus from both PLP and recuperated offspring, but remained sustained into adulthood only in PLP mice. The differential mitotic activity in the thymus from PLP and recuperated mice appeared to be influenced by changes in sex hormone concentrations and the expression of p53, p16, the androgen receptor, IL-7 (interleukin-7) and the IL-7 receptor. In conclusion, differential thymic growth may contribute to the regulation of longevity by maternal diet.
The Experiential Aspect of Rural Home-Stay among Chinese and Malay Students Using Diary Method
Authors: Musa Ghazali , Kayat Kalsom , Thirumoorthi Thinaranjeney
Published: November 2009

Tourism involving home-stays is one of the Malaysian government's key efforts to diversify its cultural tourism product. Tourists to the programme are adopted by their foster families experience a more traditional life in Malay villages. Using a diary method, this study examines the experiential aspects of home-stay holidays among domestic students in Kampung Lonek. A total of 19 diaries were content-analyzed using NVivo, which is a qualitative data analysis (QDA) computer software package produced by QSR International. Based on the findings, the home-stay experiential model is developed which explains the different phases of travel experience and their components. The on-site experience reveals three distinct dimensions: ‘environmental experience’, ‘activity, culture and knowledge experience’ and ‘human interaction experience’. The study discusses the differences between Chinese and Malay students in their home-stay experience. The article highlights its methodological, theoretical and managerial contributions.
Magnetic and optical anomalies in infinite-layer iron oxide CaFeO2 and BaFeO2: A density functional theory investigation
Authors: Ju Sheng , Cai Tian-Yi
Published: November 2009

Based on density functional theory with the generalized gradient approximation plus on-site Coulomb repulsion method, we study the electronic, magnetic, and optical properties in infinite-layer iron oxide CaFeO2 and BaFeO2. It is revealed that CaFeO2 possesses a P4¯21m tetragonal symmetry. And the single down-spin electron of Fe2+ occupies dz2 level instead of Jahn–Teller instability from the double degenerated dx2−y2 and dz2 levels predicted in crystal field theory. Magnetic structure shows great contrast between intralayer and interlayer exchange interactions. Linear dielectric function, on the other hand, exhibits obvious anisotropic behavior between in plane and out of plane responses. For the larger ionic size of Ba, BaFeO2 is found to have a P4/mmm tetragonal symmetry, which is similar with SrFeO2. In the mean time, both magnetic and optical properties exhibit much stronger anisotropic behavior. Together with the previous calculations of SrFeO2, it is found the anisotropic behaviors in these two dimensional structures are robust and independent of A-site size.
Anomalous Hall effect measurement of novel magnetic multilayers
Authors: Wong Seng-Kai , Chia Bing Hong , Srinivasan Kumar , Law Randall , Tan Ei-Leen , Tan Hang Khume , Sbiaa Rachid , Piramanayagam S. N.
Published: November 2009

We have used the method of anomalous Hall effect (AHE) to characterize magnetic thin film structures consisting of both perpendicular (normal-to-plane) and longitudinal (in-plane) anisotropies. AHE enables the simultaneous extraction of the perpendicular and in-plane magnetizations. The method is used to obtain the hysteresis loops and study the switching behavior of [Co/Pd] multilayers coupled to different seed layers. Results show that Cu seed layer helps to reduce the switching field distribution (SFD) and increase the coercivity while Co underlayer with an in-plane anisotropy helps to reduce the coercivity and increase the SFD. Furthermore, the magnetization in the Co in-plane layer is found to be pointing out of plane possibly due to exchange coupling with the [Co/Pd] multilayers.
Self-assembly of monodisperse clusters: Dependence on target geometry
Authors: Wilber Alex W. , Doye Jonathan P. K. , Louis Ard A.
Published: November 2009

We apply a simple model system of patchy particles to study monodisperse self-assembly using the Platonic solids as target structures. We find marked differences between the assembly behaviors of the different systems. Tetrahedra, octahedral, and icosahedra assemble easily, while cubes are more challenging and dodecahedra do not assemble. We relate these differences to the kinetics and thermodynamics of assembly, with the formation of large disordered aggregates a particular important competitor to correct assembly. In particular, the free energy landscapes of those targets that are easy to assemble are funnel-like, whereas for the dodecahedral system the landscape is relatively flat with little driving force to facilitate escape from disordered aggregates.
Monodisperse self-assembly in a model with protein-like interactions
Authors: Wilber Alex W. , Doye Jonathan P. K. , Louis Ard A. , Lewis Anna C. F.
Published: November 2009

We study the self-assembly behavior of patchy particles with “proteinlike” interactions that can be considered as a minimal model for the assembly of viral capsids and other shell-like protein complexes. We thoroughly explore the thermodynamics and dynamics of self-assembly as a function of the parameters of the model and find robust assembly of all target structures considered. Optimal assembly occurs in the region of parameter space where a free energy barrier regulates the rate of nucleation, thus preventing the premature exhaustion of the supply of monomers that can lead to the formation of incomplete shells. The interactions also need to be specific enough to prevent the assembly of malformed shells, but while maintaining kinetic accessibility. Free energy landscapes computed for our model have a funnel-like topography guiding the system to form the target structure and show that the torsional component of the interparticle interactions prevents the formation of disordered aggregates that would otherwise act as kinetic traps.
Nonproduct quadrature grids for solving the vibrational Schrödinger equation
Authors: Avila Gustavo , Carrington Tucker
Published: November 2009

The size of the quadrature grid required to compute potential matrix elements impedes solution of the vibrational Schrödinger equation if the potential does not have a simple form. This quadrature grid-size problem can make computing (ro)vibrational spectra impossible even if the size of the basis used to construct the Hamiltonian matrix is itself manageable. Potential matrix elements are typically computed with a direct product Gauss quadrature whose grid size scales as ND, where N is the number of points per coordinate and D is the number of dimensions. In this article we demonstrate that this problem can be mitigated by using a pruned basis set and a nonproduct Smolyak grid. The constituent 1D quadratures are designed for the weight functions important for vibrational calculations. For the SF6 stretch problem (D=6) we obtain accurate results with a grid that is more than two orders of magnitude smaller than the direct product Gauss grid. If D>6 we expect an even bigger reduction.