bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistical structure of momentum sources and sinks in the outer region of a turbulent boundary layer
Authors: GANAPATHISUBRAMANI B.
Published: June 2008

The spatial structure of momentum sources and sinks (T > 0 and T < 0; where T is the streamwise component of the Lamb vector) is examined in a turbulent boundary layer by using dual-plane particle image velocimetry data obtained in streamwise–spanwise planes at two wall-normal locations (x2/δ = 0.1 and 0.5, where x2 is the wall-normal location and δ is the boundary layer thickness). Two-point correlations of T indicate that the size of source motions remains relatively constant while the size of sink motions increases with increasing wall-normal distance. The relative strength of sink motions also increases away from the wall. The velocity field in the vicinity of source/sink motions was explored by computing cross-correlations of T with the velocity components. Source-like motions are correlated with elongated low-momentum zones that possess regions of upwash embedded within them and appear to be the strongest in areas where these low-momentum zones meander in the spanwise direction. Momentum sinks appear to be located within low-speed regions that are within larger high-momentum zones. The velocity fluctuations undergo rapid transitions between quadrants in the vicinity of sinks (i.e. both streamwise and wall-normal velocity fluctuations change sign). The length scales, over which the fluctuations change sign, are much larger at x2/δ = 0.5 than at x2/δ = 0.1.
Experiments on turbulent convection over a rotating continental shelf–slope
Authors: LIANG H. , HIGGINSON R. C. , MAXWORTHY T.
Published: June 2008

A series of Southern Hemisphere experiments have been performed to study turbulent convection on a continental shelf–slope placed in a large rotating tank filled with fresh water. Dense salt water was uniformly released at the fluid surface above the shelf. The resulting negatively buoyant bottom flow travelled over the shelf and then downslope. The non-dimensional reduced gravity of the dense downslope flow was found to scale as$G'\,{=}\,g'h^{4/3}/(B_{0}^{2/3}W)$for a fixed slope angle, whereB0the buoyancy flux at the surface,g′ the reduced gravity of the bottom flow,hthe water depth above the shelf andWthe width of the dense water source. Under rotation, a bottom Ekman layer, with superimposed roll waves, propagated down the slope and towards the left sidewall when looking down the slope. As the modified natural Rossby numberPdecreased, whereP= (B0/f3h2)1/2W/handfis the Coriolis parameter, the appearance of the bottom layer had four different forms: laminar flow, the continuous formation of waves, the periodic release of wave groups, and the periodic generation of eddies. Vortices generated on the surface were cyclonic, suggesting, but not proving, that eddies in the dense bottom layer as originally formed were anticyclonic.

With a canyon cut from the middle of the shelf to the bottom of the slope,G′ values measured in dense flows to the left of the canyon, were significantly reduced. The canyon channelled a large amount of dense fluid with a buoyancy considerably larger than that of dense flows on the slope. However, the flow regime criteria remained basically unchanged with eddies and downslope Ekman layer being able to partially cross the canyon.
On steady linear diffusion-driven flow
Authors: PAGE M. A. , JOHNSON E. R.
Published: June 2008

Wunsch (1970) and Phillips (1970) (Deep-Sea Res. vol. 17, pp. 293, 435) showed that a temperature flux condition on a sloping non-slip surface in a stratified fluid can generate a slow steady upward flow along a thin ‘buoyancy layer’. Their analysis is extended here to the more-general case of steady flow in a contained fluid where buoyancy layers may expel or entrain fluid from their outer edge. A compatibility condition that relates the mass flux and temperature gradient along that edge is derived, and this allows the fluid recirculation and temperature perturbation to be determined in the broader-scale ‘outer flow’ region. The analysis applies when the Wunsch–Phillips parameterRis small, in the linear case for which the density variations are dominated by a constant vertical gradient.
Stochastic low-dimensional modelling of a random laminar wake past a circular cylinder
Authors: VENTURI DANIELE , WAN XIAOLIANG , KARNIADAKIS GEORGE EM
Published: June 2008

We present a new compact expansion of a random flow field into stochastic spatial modes, hence extending the proper orthogonal decomposition (POD) to noisy (non-coherent) flows. As a prototype problem, we consider unsteady laminar flow past a circular cylinder subject to random inflow characterized as a stationary Gaussian process. We first obtain random snapshots from full stochastic simulations (based on polynomial chaos representations), and subsequently extract a small number of deterministic modes and corresponding stochastic modes by solving a temporal eigenvalue problem. Finally, we determine optimal sets of random projections for the stochastic Navier–Stokes equations, and construct reduced-order stochastic Galerkin models. We show that the number of stochastic modes required in the reconstruction does not directly depend on the dimensionality of the flow system. The framework we propose is general and it may also be useful in analysing turbulent flows, e.g. in quantifying the statistics of energy exchange between coherent modes.
Instability and breakdown of a vertical vortex pair in a strongly stratified fluid
Authors: WAITE MICHAEL L. , SMOLARKIEWICZ PIOTR K.
Published: June 2008

The dynamics of a counter-rotating pair of columnar vortices aligned parallel to a stable density gradient are investigated. By means of numerical simulation, we extend the linear analyses and laboratory experiments of Billant & Chomaz (J. Fluid Mech. vol. 418, p. 167; vol. 419, pp. 29, 65 (2000)) to the fully nonlinear, large-Reynolds-number regime. A range of stratifications and vertical length scales is considered, withFrh< 0.2 and 0.1 <Frz< 10. HereFrh≡U/(NR) andFrz≡Ukz/Nare the horizontal and vertical Froude numbers,UandRare the horizontal velocity and length scales of the vortices,Nis the Brunt–Väisälä frequency, and 2π/kzis the vertical wavelength of a small initial perturbation. At early times withFrz< 1, linear predictions for the zigzag instability are reproduced. Short-wavelength perturbations withFrz> 1 are found to be unstable as well, with growth rates only slightly less than those of the zigzag instability but with very different structure. At later times, the large-Reynolds-number evolution diverges profoundly from the moderate-Reynolds-number laboratory experiments as the instabilities transition to turbulence. For the zigzag instability, this transition occurs when density perturbations generated by the vortex bending become gravitationally unstable. The resulting turbulence rapidly destroys the vortex pair. We derive the criterion η/R≈ 0.2/Frzfor the onset of gravitational instability, where η is the maximum horizontal displacement of the bent vortices, and refine it to account for a finite twisting disturbance. Our simulations agree for the fastest growing wavelengths 0.3 <Frz< 0.8. Short perturbations withFrz> 1 saturate at low amplitude, preserving the columnar structure of the vortices well after the generation of turbulence. Viscosity is shown to suppress the transition to turbulence for Reynolds numberRe≲ 80/Frh, yielding laminar dynamics and, under certain conditions, pancake vortices like those observed in the laboratory.
Simulation of flow around a row of square cylinders
Authors: KUMAR SHASHI RANJAN , SHARMA ATUL , AGRAWAL AMIT
Published: June 2008

In this paper, the low-Reynolds number (Re= 80) flow around a row of nine square cylinders placed normal to the oncoming flow is investigated using the lattice-Boltzmann method. The effects of the cylinder spacing on the flow are studied for spacing to diameter ratios of 0.3 to 12. No significant interaction between the wakes is observed with spacings greater than six times the diameter. At smaller spacings, the flow regimes as revealed by vorticity field and drag coefficient signal are: synchronized, quasi-periodic and chaotic. These regimes are shown to result from the interaction between primary (vortex shedding) and secondary (cylinder interaction) frequencies; the strength of the latter frequency in turn depends on the cylinder spacing. The secondary frequency is also related to transition between narrow and wide wakes behind a cylinder.

The mean drag coefficient and Strouhal number are found to increase rapidly with a decrease in spacing; correlations of these parameters with spacing are proposed. The Strouhal number based on gap velocity becomes approximately constant for a large range of spacings, highlighting the significance of gap velocity for this class of flows. It is also possible to analyse the vortex pattern in the synchronized and quasi-periodic regimes with the help of vorticity dynamics. These results, most of which have been obtained for the first time, are of fundamental significance.
The Voith Turbo Fin (VTF) A New System To Improve The Performance Of Escort Tractor Voith Tugs
Authors: Baniela Santiago Iglesias , Melón Enrique García
Published: June 2008

The geometry of the skeg in the Escort Tractor Voith tugs is the result of a series of intense investigations in the forms of the tug and its fins, oriented to get a significant improvement in the forces on the towing line when the indirect method is used in the escort towing. For that, and with the aim of getting the best behaviour of this fin, a variety of options have been investigated for years, evaluating its merits in terms of lift force and complexity to reach the present designs, which are adapted to the functions which the tug is destined to carry out. With the object of optimizing the lift force in the skeg when the indirect method is used in the escort towing, and after long investigations, the Voith Turbo Marine has incorporated a rotating cylinder at the leading edge to its design in escort towing for the first time at the beginning of 2005. The leading edge is the part over which the water flow first falls upon in normal escort operation conditions, calling this new development Voith Turbo Fin (VTF) to the system as a whole (skeg and rotating cylinder). This fin is analyzed in this article especially with regard to its basis, ways of operation and efficiency of the novel joining rotating cylinder.
Detecting RFI Through Integrity Monitoring at a DGPS Reference Station
Authors: Yun Youngsun , Kee Changdon , Rife Jason , Luo Ming , Pullen Sam , Enge Per
Published: June 2008

Because GPS is a radio navigation system which has a very low power level, it is vulnerable to RFI. Excessive RFI could cause receiver performance degradation, such as degradation of position accuracy, loss of lock and increased acquisition time. After GPS modernization plans introduce dual-frequency civil signals to mitigate ionospheric errors, RFI will remain as one of the dominant threats for differential GPS navigation systems. Examples of safety-critical civil aviation and military missions threatened by RFI include the Local Area Augmentation System (LAAS) and the Joint Precision Approach and Landing System (JPALS). This paper focuses on RFI mitigation through integrity monitoring for a DGPS system like LAAS or JPALS. The mitigation strategy consists of two parts. First, the paper develops a new RFI detection method, using a raw divergence statistic. Second, the paper investigates strategies for maintaining integrity in the case that RFI is detected.

To validate the utility of the divergence-based RFI monitor, this paper takes an experimental approach. The experiments assess the performance of the divergence metric and compare it to existing alternatives for RFI detection, such as metrics for Automatic Gain Control (AGC) and carrier-to-noise ratio (C/N0). Generating a monitoring threshold for these statistics proves challenging, because the threshold depends both on the type of RFI threat (e.g. continuous wave, narrow band, wideband, pulsed) and on environmental conditions, such as temperature. As experiments illustrate, the divergence statistic resolves these limitations, as divergence directly estimates ranging source error, independent of the type of RFI threat or the environmental conditions.
A Remote Vision Guidance System for Visually Impaired Pedestrians
Authors: Hunaiti Z. , Garaj V. , Balachandran W.
Published: June 2008

This paper presents research and development work on a novel system with a view of developing a navigation system for the guidance of visually impaired pedestrians. The prime aim of the new developed system is to enhance the mobility of visually impaired pedestrians using remote guidance provided by sighted person. However, the system can be used in many other applications. The system implementation is based on the integration of the Global Positioning System (GPS), Geographical Information System (GIS) database and a remote vision facility over the third generation (3G) of mobile networks, providing a technological platform enabling visually impaired pedestrians to be guided remotely by a sighted guide.
Human-competitive machine invention by means of genetic programming
Authors: Koza John R.
Published: June 2008

Genetic programming is a systematic method for getting computers to automatically solve problems. Genetic programming uses the Darwinian principle of natural selection and analogs of recombination (crossover), mutation, gene duplication, gene deletion, and certain mechanisms of developmental biology to progressively breed, over a series of many generations, an improved population of candidate solutions to a problem. This paper makes the points that genetic programming now routinely delivers human-competitive machine intelligence for problems of automated design and can serve as an automated invention machine.
SWINBURNE, “HERTHA,” AND THE VOICE OF LANGUAGE
Authors: McGann Jerome
Published: June 2008

This soaring passage comesfrom Max Müller's celebrated 1855 essay on linguistic anthropology. I start with it because no brief text better captures the import of Swinburne's poetic manifesto “Hertha.” And “Hertha” is important because, like “Anactoria,” it is pivotal in Swinburne's ambitious poetic program.
STARVATION IN VICTORIAN CHRISTMAS FICTION
Authors: Moore Tara
Published: June 2008

It may seem thatChristmas literature, with its glorified descriptions of overflowing tables and conviviality, has no place in a discussion of that other extreme, starvation. However, much of the nineteenth-century literature containing narratives of Christmas speaks directly to national fears of famine. Starvation entered the print matter of Christmas first as part of a social argument and later as a concern for the abiding national identity that had become intertwined with Christmas itself and, more symbolically, Christmas fare. Writers including Charles Dickens, Benjamin Farjeon, Augustus and Henry Mayhew, the creators ofPunch, and Mary Elizabeth Braddon authored Christmas pieces that showcase literary reactions to the developing issues of hunger throughout their century. This essay offers an overview of the treatment of starvation in the Christmas literature of the nineteenth century.
“DEEPLY INDEBTED TO THE TEA-PLANT”: REPRESENTATIONS OF ENGLISH NATIONAL IDENTITY IN VICTORIAN HISTORIES OF TEA
Authors: Fromer Julie E.
Published: June 2008

These words were pennedby a professor of the Royal Medico-Botanical Society in the late 1830s to commemorate the “recent discovery in British India of the Tea Plant” (vii). Yet although written near the beginning of the Victorian era, their sentiment – that tea was both an element of national self-definition and a stimulator of the individual prosperity and wellbeing on which that polity was based – nonetheless epitomizes the broader sweep of the nineteenth century's engagement with that article of consumption. How tea came to occupy this role, and why, is the subject of this essay, which focuses on the book-length tea history – a slightly peculiar genre that blurs the boundaries between fiction and non-fiction, advertisement and travelogue, personal account and scientific treatise. These histories appeared throughout the nineteenth century and often were explicitly funded by various segments of the tea industry (thus resembling the nineteenth-century equivalent of an infomercial). Because of their direct relationship to commercial and trading concerns, their role in recording and shaping the taste for the beverage, and their dissemination across a fairly broad public, tea histories offer an important, intertextual index of the Victorians' relationship to the beverage, as well as the way in which the relationship between home and Empire was constituted and changed over the course of the century.
Consumer perceptions of fruit and vegetables serving sizes
Authors: Pollard Christina M , Daly Alison M , Binns Colin W
Published: June 2008

Objective

To assess consumer understanding of fruit and vegetable serving sizes.

Design

The Western Australian Health Department launched the Go for 2&5® campaign to promote fruit and vegetables in March 2002. The Health & Wellbeing Surveillance System surveyed 1108 adults, aged 16 years and over, between September and November 2002 about what constituted a serving of fruit and of vegetables, their usual daily fruit and vegetables intake, and their recall of the campaign.

Setting

The study was undertaken as a part of a public health intervention – social marketing campaign in Western Australia, which had a population of 1 927 000 in 2002.

Results

Forty-two per cent of respondents knew that the fruit serving size was one piece and only 14·5 % reported the ½ cup vegetable serving size. The mean fruit intake was 1·8 (95 % CI 1·7, 1·8) servings/d and the mean vegetable intake was 2·8 (95 % CI 2·7, 3·0) servings/d. Vegetable intake was associated with being female (P = 0·006), increasing age (P < 0·0001), awareness of the campaign (P = 0·031) and knowledge of standard serving size (P = 0·006). Fruit consumption was associated with being female (P = 0·007). Fruit and vegetable intakes were not associated with educational attainment or household income.

Conclusions

The Go for 2&5® campaign uses a prescriptive message to promote increased consumption of fruit and vegetables. Respondent’s knowledge of the standard of serving sizes for fruit and vegetables suggests there is value in separating fruit and vegetable recommendations in messages to encourage increased consumption.
Development and piloting of a community health worker-based intervention for the prevention of diabetes among New Zealand Maori in Te Wai o Rona: Diabetes Prevention Strategy
Authors: Simmons D , Rush E , Crook N ,   on behalf of the Te Wai o Rona: Diabetes Prevention Strategy Team
Published: June 2008

Objective

The progression from impaired glucose tolerance (IGT)/impaired fasting glucose (IFG) to type 2 diabetes can be prevented or delayed through intensive lifestyle changes. How to translate this to implementation across whole communities remains unclear. We now describe the results to a pilot of a personal trainer (Maori Community Health Worker, MCHW) approach among Maori in New Zealand.

Design, setting and subjects

A randomised cluster-controlled trial of intensive lifestyle change was commenced among 5240 non-pregnant Maori family members without diabetes from 106 rural and 106 urban geographical clusters. Baseline assessments included lifestyle questionnaires, anthropometric measurements and venesection. A pilot study (Vanguard Study) cohort of 160 participants were weighed before and during MCHW intervention, and compared with fifty-two participants weighed immediately before intervention and with 1143 participants from the same geographical area. Interactions between participants and the MCHW were reported using personal digital assistants with a programmed detailed structured approach to each interview.

Results

During the Vanguard Study, participants and MCHW found the messages, toolkit and delivery approach acceptable. Those with IGT/IFG diagnosed (n 27) experienced significant weight loss after screening and during the Vanguard Study (5·2 (sd 6·6) kg, paired t test P < 0·01). Significant weight loss occurred during the Vanguard Study among all participants (−1·3 (sd 3·6) kg, P < 0·001).

Conclusions

Comparable initial weight loss was shown among those with IGT/IFG and those from existing trials. Community-wide prevention programmes are feasible among Maori and are likely to result in significant reductions in the incidence of diabetes.
Southern Ocean mixed‐layer depth from Argo float profiles
Authors: Dong Shenfu , Sprintall Janet , Gille Sarah T. , Talley Lynne
Published: June 2008

Argo float profiles of temperature, salinity, and pressure are used to derive the mixed‐layer depth (MLD) in the Southern Ocean. MLD is determined from individual profiles using both potential density and potential temperature criteria, and a monthly climatology is derived from individual MLDs using an objective mapping method. Quantitative data are available in the auxiliary material. The spatial structures of MLDs are similar in each month, with deep mixed layers within and just north of the Antarctic Circumpolar Current (ACC) in the Pacific and Indian oceans. The deepest mixed layers are found from June to October and are located just north of the ACC where Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water (SAMW) are formed. Examination of individual MLDs indicates that deep mixed layers (MLD ≥ 400 m) from both the density and temperature criteria are concentrated in a narrow surface density band which is within the density range of SAMW. The surface salinity for these deep mixed layers associated with the SAMW formation are slightly fresher compared to historical estimates. Differences in air‐sea heat exchanges, wind stress, and wind stress curl in the Pacific and Indian oceans suggest that the mode water formation in each ocean basin may be preconditioned by different processes. Wind mixing and Ekman transport of cold water from the south may assist the SAMW formation in the Indian Ocean. In the eastern Pacific, the formation of mode water is potentially preconditioned by the relative strong cooling and weak stratification from upwelling.
Carbon‐based primary productivity modeling with vertically resolved photoacclimation
Authors: Westberry T. , Behrenfeld M. J. , Siegel D. A. , Boss E.
Published: June 2008

Net primary production (NPP) is commonly modeled as a function of chlorophyll concentration (Chl), even though it has been long recognized that variability in intracellular chlorophyll content from light acclimation and nutrient stress confounds the relationship between Chl and phytoplankton biomass. It was suggested previously that satellite estimates of backscattering can be related to phytoplankton carbon biomass (C) under conditions of a conserved particle size distribution or a relatively stable relationship between C and total particulate organic carbon. Together, C and Chl can be used to describe physiological state (through variations in Chl:C ratios) and NPP. Here, we fully develop the carbon‐based productivity model (CbPM) to include information on the subsurface light field and nitracline depths to parameterize photoacclimation and nutrient stress throughout the water column. This depth‐resolved approach produces profiles of biological properties (Chl, C, NPP) that are broadly consistent with observations. The CbPM is validated using regional in situ data sets of irradiance‐derived products, phytoplankton chlorophyll:carbon ratios, and measured NPP rates. CbPM‐based distributions of global NPP are significantly different in both space and time from previous Chl‐based estimates because of the distinction between biomass and physiological influences on global Chl fields. The new model yields annual, areally integrated water column production of ∼52 Pg C a−1 for the global oceans.
Impact of penetrative solar radiation on the diagnosis of water mass transformation in the Mediterranean Sea
Authors: Bozec Alexandra , Bouruet‐Aubertot Pascale , Iudicone Daniele , Crépon Michel
Published: June 2008

We applied a revised diagnosis of water mass formation and mixing to a 1/8° resolution ocean model of the Mediterranean Sea. The diagnosis method used and presented by Iudicone et al. (2008) is similar to that developed by Walin (1982) and applied to the Mediterranean Sea by Tziperman and Speer (1994), to which we added a penetrative solar radiation. Both the prognostic model and the diagnostic method were in agreement with respect to the solar flux parameterization. Major changes were observed in the yearly budget of water mass transformation when the penetrative solar radiation is taken into account in the diagnosis. Annual estimates of water mass formation rates were decreased by a factor of two, with values within the range [−3.7 Sv, 1.5 Sv] compared to [−6 Sv, 3 Sv]. This decrease resulted from a lower seasonal variation when penetrative solar radiation was included. This can be explained by the fact that the solar radiation flux acted over a wider range of seawater density leading to lower net values over a given density interval. The major impact of the penetrative solar radiation occurred during spring and summer. Newly formed dense water was then transformed into lighter water with a rate reaching a value about 50% of that of the water mass formation rate in winter. Another consequence was that mixing processes which counteract formation rate in yearly budget of water mass formation rates, were overestimated. We showed that, in spring and summer, about a third of the transformation took place below the surface layer.
Alaska's Pavlof Volcano Ends 11‐Year Repose
Authors: Waythomas Christopher F. , Prejean Stephanie G. , McNutt Stephen R.
Published: June 2008

After an 11‐year period of repose, Pavlof volcano on the Alaska Peninsula (Figure 1) began an episode of Strombolian eruption lasting 31 days, from 14 August to 13 September 2007.

The eruption began abruptly on 14 August after a minor increase in seismicity the previous day. Nearly continuous lava fountaining, explosions, and lahars caused by minor disruption of the ice and snow cover on the volcano characterized the eruption. The eruption also produced diffuse ash plumes that reached 5–6 kilometers above sea level, but the plumes were too small and did not extend high enough to affect local or regional air travel. Melting of snow and ice on the upper part of the edifice by hot debris avalanches and lava resulted in numerous lahars that entered the sea and inundated a 2×106 square meter area on the volcanos southern slope.
Input Sought on Earth Surface Processes
Authors: Eide Elizabeth
Published: June 2008

The U.S. National Research Council, at the request of the U.S. National Science Foundation, is conducting a study to assess (1) the state of the art of the multidisciplinary field of Earth surface processes, (2) the fundamental research questions in the future for the field, and (3) the challenges and opportunities related to answering these questions and advancing the field. The committee is addressing the task by considering research on the dynamic biological, chemical, physical, and human processes, interactions, and feedback mechanisms that affect the shape of Earths surface across a range of spatial and temporal scales, from continental interiors to the oceans, and from polar to equatorial regions.
Ultralow‐Frequency Magnetic Fields Preceding Large Earthquakes
Authors: Fraser‐Smith Antony C.
Published: June 2008

The Great Alaska Earthquake (M 9.2) of 27 March 1964 was the largest earthquake ever to strike the United States in modern times and one of the largest ever recorded anywhere. Later that year, Moore [1964], in a surprisingly rarely cited paper, reported the occurrence of strong ultralow‐frequency (ULF; ≤10 hertz) magnetic field disturbances at Kodiak, Alaska, in the 1–2 hours before the earthquake. That report has since been followed by others [Fraser‐Smith et al., 1990; Kopytenko et al., 1993; Hayakawa et al., 1996; see also Molchanov et al., 1992] similarly describing the occurrence of large‐amplitude ULF magnetic field fluctuations before other large earthquakes (“large” describes earthquakes with magnitudes M ∼7 or greater). These reports involving four separate, large earthquakes were made by four different groups and the results were published in well‐known, refereed scientific journals, so there is no doubt that there is evidence for the existence of comparatively large ULF magnetic field fluctuations preceding large earthquakes.
Development of a Pan‐Arctic Database for River Chemistry
Authors: McClelland James W. , Holmes R. Max , Peterson Bruce J. , Amon Rainer , Brabets Tim , Cooper Lee , Gibson John , Gordeev Viacheslav V. , Guay Christopher , Milburn David , Staples Robin , Raymond Peter A. , Shiklomanov Igor , Striegl Robert , Zhulidov Alexander , Gurtovaya Tanya , Zimov Sergey
Published: June 2008

More than 10% of all continental runoff flows into the Arctic Ocean. This runoff is a dominant feature of the Arctic Ocean with respect to water column structure and circulation. Yet understanding of the chemical characteristics of runoff from the pan‐Arctic watershed is surprisingly limited. The Pan‐ Arctic River Transport of Nutrients, Organic Matter, and Suspended Sediments ( PARTNERS) project was initiated in 2002 to help remedy this deficit, and an extraordinary data set has emerged over the past few years as a result of the effort. This data set is publicly available through the Cooperative Arctic Data and Information Service (CADIS) of the Arctic Observing Network (AON). Details about data access are provided below.
Numerical Modeling of Ocean Circulation
Authors: Haine Thomas W. N.
Published: June 2008

In physical ocean sciences, with little opportunity to experiment on the natural system, numerical circulation models provide estimates of ocean currents that are increasingly important in leading this field. Probably the most common application of these tools is to study the large‐scale, lowfrequency currents of the global ocean using a general circulation model (GCM). Ocean GCMs are used in coupled climate models, familiar from the Intergovernmental Panel on Climate Change, for instance. Ocean models are also widely used for operational purposes, including seasonal forecasts (especially for El NiñoSouthern Oscillation), storm surges, tides, and tsunamis. Dozens of basic studies of ocean fluid dynamics and biogeochemical cycles also exist.
Improved horizontal wind model HWM07 enables estimation of equatorial ionospheric electric fields from satellite magnetic measurements
Authors: Alken Patrick , Maus Stefan , Emmert John , Drob Douglas P.
Published: June 2008

Horizontal neutral winds play an important role in low‐latitude ionospheric E and F‐region dynamics. In particular, the zonal winds have strong effects on the local structure of the low‐latitude ionospheric current system. Accurate wind specification is therefore essential for modeling these currents. In order to investigate the retrieval of eastward electric fields from satellite‐derived equatorial electrojet (EEJ) profiles, we consider a provisional Horizontal Wind Model (HWM07) and its implications for the meridional structure of the EEJ. We find that EEJ current profiles predicted using HWM07 agree better with CHAMP magnetometer‐derived current profiles than EEJ profiles predicted using the older HWM93 model. The improved wind model opens exciting new possibilities of determining the day‐side eastward electric field in the equatorial ionosphere from satellite magnetic field measurements.
Characterization of Fe(II) oxidizing bacterial activities and communities at two acidic Appalachian coalmine drainage-impacted sites
Authors: Senko John M , Wanjugi Pauline , Lucas Melanie , Bruns Mary Ann , Burgos William D
Published: June 2008

We characterized the microbiologically mediated oxidative precipitation of Fe(II) from coalmine-derived acidic mine drainage (AMD) along flow-paths at two sites in northern Pennsylvania. At the Gum Boot site, dissolved Fe(II) was efficiently removed from AMD whereas minimal Fe(II) removal occurred at the Fridays-2 site. Neither site received human intervention to treat the AMD. Culturable Fe(II) oxidizing bacteria were most abundant at sampling locations along the AMD flow path corresponding to greatest Fe(II) removal and where overlying water contained abundant dissolved O2. Rates of Fe(II) oxidation determined in laboratory-based sediment incubations were also greatest at these sampling locations. Ribosomal RNA intergenic spacer analysis and sequencing of partial 16S rRNA genes recovered from sediment bacterial communities revealed similarities among populations at points receiving regular inputs of Fe(II)-rich AMD and provided evidence for the presence of bacterial lineages capable of Fe(II) oxidation. A notable difference between bacterial communities at the two sites was the abundance of Chloroflexi-affiliated 16S rRNA gene sequences in clone libraries derived from the Gum Boot sediments. Our results suggest that inexpensive and reliable AMD treatment strategies can be implemented by mimicking the conditions present at the Gum Boot field site.
Adiposity Gain During Childhood, ACE I/D Polymorphisms and Metabolic Outcomes
Authors: Ponsonby Anne‐Louise , Blizzard Leigh , Pezic Angela , Cochrane Jenny A. , Ellis Justine A. , Morley Ruth , Dickinson Jo L. , Sale Michele M. , Richards Stephen M. , Dwyer Terence
Published: June 2008

We aimed to (i) determine the relative importance of childhood gain in upper body adiposity for insulin resistance (IR) and triglyceridemia (TG); (ii) examine whether the associations between adiposity and metabolic indices were more evident in those with the ACE DD genotype. We examined a birth cohort study of 292 children with measures in the neonatal period (day 4) including subscapular and triceps skinfolds; repeat skinfold measures at age 8, cardiorespiratory (CR) fitness, IR by the homeostasis model assessment (HOMA) equation (HOMA‐IR) and serum triglyceride (TG) concentrations and measures of ACE I/D gene variants. A multiple linear regression analysis incorporating a life course approach was undertaken. Childhood gain in upper body adiposity was positively associated with HOMA‐IR and TG independently of neonatal skinfolds (P ≤ 0.02). The magnitude of these associations was higher among those of the ACE DD genotype. For example, subscapular skinfold gain was not strongly associated with HOMA‐IR or TG among those with II or ID genotype (b = 0.03, P = 0.05; b = 0.02, P = 0.18 respectively) but was positively associated among those with the DD genotype (b = 0.11, P = 0.001; b = 0.08, P = 0.003); difference in effect P = 0.05; P = 0.01 respectively. Upper body fat accumulation during childhood was positively associated with HOMA‐IR and TG independently of neonatal skinfolds. Further, the stronger associations for those with the ACE DD genotype is consistent with randomised controlled trial findings that ACE inhibition is associated with a reduced risk of developing type 2 diabetes. Further work is required to confirm and extend these findings.
Replication of Genetic Effects of FTO Polymorphisms on BMI in a Korean Population
Authors: Cha Seong W. , Choi Sun M. , Kim Kil S. , Park Byung L. , Kim Jae R. , Kim Jong Y. , Shin Hyoung D.
Published: June 2008

It has been newly reported in recent studies that single‐nucleotide polymorphisms (SNPs) in the first intron of the FTO gene have been associated with BMI in whites. To determine whether the gene is associated with BMI in Asians also, we performed a replication study of the association of the gene with BMI in a Korean population. Two SNPs in the FTO gene (rs1421085 and rs17817449) were genotyped using the TaqMan method in a Korean population (n = 1,733). The two SNPs were then used for an association study with BMI through statistical analyses. The rs1421085 C allele (P = 0.0015, effect size = 0.0056) and rs17817449 G allele (P = 0.0019, effect size = 0.0053) were found to be significantly associated with increased BMI. Our results suggest that FTO may be one of the worldwide obesity‐risk genes.
Effects of Temptation and Weight on Hedonics and Motivation to Eat in Women
Authors: Ouwehand Carolijn , De Ridder Denise T.D.
Published: June 2008

Objective: The aim of the present study was to examine the extent to which food temptation influences liking, the hedonics of food, and wanting, the motivation to eat, and whether this effect differed between normal‐weight and overweight women.

Methods and Procedures: Ninety‐seven normal‐weight and overweight women participated in a randomized experiment, which used a two‐by‐two design with food temptation and body weight as independent variables. ANOVAs tested the effect of these factors on wanting and liking.

Results: The most important finding of this study was that food temptation had a significant effect on wanting, but not on liking. Wanting was mainly influenced by temptation; however, this effect was moderated by weight. Interestingly, temptation caused a decrease in wanting, but only in normal‐weight women. This effect of temptation could not be explained by a change in affect after manipulation or a difference in hunger before the start of the experiment.

Discussion: A possible explanation for the finding that normal‐weight women showed a decline in wanting after the confrontation with highly palatable food may be that normal‐weight women are protected by a higher sensory‐specific satiety. Moreover, it is possible that in these women goals regarding, for example, weight maintenance are more easily evoked, which may remind them of the positive consequences of not yielding into temptation.
Influence of Weekend Lifestyle Patterns on Body Weight
Authors: Racette Susan B. , Weiss Edward P. , Schechtman Kenneth B. , Steger‐May Karen , Villareal Dennis T. , Obert Kathleen A. , Holloszy John O. ,   Washington University School of Medicine CALERIE Team
Published: June 2008

Objective: To determine whether alterations in diet and/or activity patterns during weekends contribute to weight gain or hinder weight loss.

Methods and Procedures: Randomized, controlled trial comparing 1 year of caloric restriction (CR) with 1 year of daily exercise (EX). Subjects included 48 healthy adults (30F, 18M) aged 50–60 years with BMI 23.5–29.9 kg/m2. Body weight was measured on 7 consecutive mornings for a total of 165 weeks at baseline and 437 weeks during the 1‐year interventions. Daily weight changes were calculated for weekends (Friday to Monday) and weekdays (Monday to Friday). Daily energy intake was estimated using food diaries; daily physical activity was measured using accelerometers. Both measures were validated against doubly labeled water (DLW).

Results: At baseline, participants consistently gained weight on weekend days (+0.06 ± 0.03 kg/day, (mean ± s.e.), P = 0.02), but not on weekdays (−0.02 ± 0.02 kg/day, P = 0.18). This was attributable to higher dietary intake on Saturdays and lower physical activity on Sundays relative to weekdays (both P < 0.05). During the interventions, both CR and EX participants were in negative energy balance on weekdays (P < 0.005). On weekends, however, CR participants stopped losing weight, and EX participants gained weight (+0.08 ± 0.03 kg/day, P < 0.0001) due to higher dietary intakes on weekends. This helps to explain the slower‐than‐expected rate of weight loss during the interventions.

Discussion: Alterations in lifestyle behaviors on weekends contribute to weight gain or cessation of weight loss on weekends. These results provide one explanation for the relatively slow rates of weight loss observed in many studies, and the difficulty with maintaining significant weight loss.
Specific effects of KChIP3/calsenilin/DREAM, but not KChIPs 1, 2 and 4, on calcium signalling and regulated secretion in PC12 cells
Authors: Venn Neil , Haynes Lee P. , Burgoyne Robert D.
Published: June 2008

The KChIPs (K+ channel-interacting proteins) are members of the NCS (neuronal calcium sensor) protein family of Ca2+-binding proteins. It is unclear to what extent the KChIPs have distinct functions although they all interact with Kv4 K+ channels. KChIP3 has also been shown to repress transcription of specific genes via binding to DRE (downstream regulatory element) motifs and all KChIPs may share this function. In the present study, we have compared the function of isoforms of the four KChIPs. KChIPs 1–4 were found to stimulate the traffic of Kv4.2 channels to the plasma membrane. KChIP3 expression in PC12 cells resulted in an increase in exocytosis evoked by activation of purinergic receptors. In contrast, KChIPs 1, 2 and 4, although expressed to the same extent, had no effect on secretion. In addition, KChIP3 but not KChIPs 1, 2 and 4 modified the ATP-induced Ca2+ signal resulting in a delay in recovery after the peak Ca2+ elevation and also specifically resulted in down-regulation of the Na+/Ca2+ exchanger NCX3, which could explain the effects on the Ca2+ signal and secretion. Regulation of NCX3 by KChIP3 has been shown to occur via its DREAM (DRE antagonist modulator) function [Gomez-Villafuertes, Torres, Barrio, Savignac, Gabellini, Rizzato, Pintado, Gutierrez-Adan, Mellstrom, Carafoli and Naranjo (2005) J. Neurosci. 25, 10822–10830] suggesting that this activity might depend on the cellular context of expression of the various KChIPs. These results reveal a new role for KChIP3 in the regulation of Ca2+-regulated secretion and also suggest that the functions of each of the KChIPs may be more specialized than previously appreciated.
Elastic property of fcc metal nanowires via an atomic-scale analysis
Authors: Qiao Li , Zheng Xiaojing
Published: June 2008

A simple atomic-scale model based on the distortion of the unit cell generating the nanowire is proposed to predict the elastic characteristics of fcc metal nanowires. It allows for an analytical study on the mechanical behavior of nanomaterials from the perspective of atomic interactions. Bond-strength enhancing arising from the spontaneous bond relaxation has significant effects on the elastic properties of metal nanowires, which can be described by a scale function. Contribution from effects related to surface roughness and surface oxidation to the elastic modulus of nanostructures is also considered. There is good qualitative agreement between theoretical predictions and experimental observations.
Vibrational cooling of spin-stretched dimer states by He buffer gas: Quantum calculations for Li2(aΣu+3) at ultralow energies
Authors: Bovino S. , Bodo E. , Yurtsever E. , Gianturco F. A.
Published: June 2008

The interaction between the triplet state of the lithium dimer, Li27, with He4 is obtained from accurate ab initio calculations where the vibrational dependence of the potential is newly computed. Vibrational quenching dynamics within a coupled-channel quantum treatment is carried out at ultralow energies, and large differences in efficiency as a function of the initial vibrational state of the targets are found as one compares the triplet results with those of the singlet state of the same target.
Accurate calculations of free-energy differences by the distribution method
Authors: Wu Di
Published: June 2008

We employ the strategy used in the successive umbrella sampling method [P. Virnau and M. Müller, J. Chem. Phys. 120, 10925 (2004)] to obtain the energy-difference distribution over its desired range. This is very helpful in calculating free-energy differences, where the source of the error is well recognized as the insufficient sampling over the relevant tail region in the energy-difference distribution. The distribution method proposed here employs the idea of restricting the sampling within an appropriate energy range, as was presented by Shing and Gubbins in their restricted umbrella sampling method [Mol. Phys. 46, 1109 (1982)]. We demonstrate the efficiency of the distribution method by calculating the free-energy difference of a model of harmonic oscillators where the systems exhibit nonoverlap features in their important phase spaces through the original Metropolis sampling. For this particular case, we show that the distribution method outperforms the free-energy perturbation method and even the Bennett’s acceptance ratio method [J. Comput. Phys. 22, 245 (1976)] with the fastest convergence and the smallest relative errors. We further demonstrate the application of the distribution method with a simple point charge water model.
Effects of hydration on the mechanical response of individual collagen fibrils
Authors: Grant Colin A. , Brockwell David J. , Radford Sheena E. , Thomson Neil H.
Published: June 2008

Collagen fibrils prepared from bovine Achilles tendon have been mechanically tested through nanoindentation by an atomic force microscope using force volume analysis. In ambient conditions where the fibrils are expected to be dehydrated, the elastic modulus was determined to be 1.9±0.5GPa, while under aqueous fluid, it decreased by three orders of magnitude to 1.2±0.1MPa. In air, fibril fracture occurred along the axis and the crack lengths were quantized to the D-banding periodicity. The apparent hardness of the fibrils was estimated to be in the range of 0.35–0.6GPa.
Tunable quantum coupling in a II-VI quantum dot molecule
Authors: Bacher G. , Welsch M. K. , Forchel A. , Lyanda-Geller Y. , Reinecke T. L. , Becker C. R. , Molenkamp L. W.
Published: June 2008

Single quantum dot molecules have been fabricated from coupled quantum well structures of (Cd, Mn, Mg) Te alloy materials using a selective interdiffusion technique. Incorporation of Mn ions in one of the quantum dots in the molecule results in pairs of quantum dots with markedly different spin splittings. By comparing the observed magnetic field dependence of the optical polarization in photoluminescence with detailed calculations, we show that the coupling between the dots is quantum mechanical tunnel coupling and that it is tunable.
Thermal quenching investigation in chemical vapor deposited diamond by simultaneous detection of thermally stimulated luminescence and conductivity
Authors: Benabdesselam M. , Petitfils A. , Wrobel F. , Butler J. E. , Mady F.
Published: June 2008

Chemical vapor deposited (CVD) diamond is a very promising material that is extensively studied in many technologies. Thermally stimulated luminescence (TSL) experiments demonstrate that an important thermal quenching phenomenon occurs with microwave plasma chemical vapor deposited diamond. This phenomenon leads to a large discrepancy on the determination of electronic trap parameters. Thermally stimulated conductivity phenomenon is not affected by thermal quenching and allows an easier determination of trap parameters than TSL measurements. The difference between the two ways of computing trap energy is found to be around 4% instead of 28%, which is obtained when thermal quenching fails.
Modeling capped ferroelectric media for probe storage recording
Authors: Gidon S.
Published: June 2008

For probe storage applications, we have modeled the electrical behavior of a monocrystal, single domain, out-of-plane polarized ferroelectric layer capped with a partially conductive layer. The model shows a “domino” type ferroelectric switching on the overall thickness of the layer. The observed current signal is highly dependent on the tip size media contact. For large contact, simulation results fit well with experimental measurements. Predicted results for tip size smaller than the media thickness show rounded Lissajoux curves for the current and the apparent polarization. Dots readout through current detection is also analyzed, giving access to function of transfer modulation considerations related to tip size contact.