bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear reflection of grazing acoustic shock waves: unsteady transition from von Neumann to Mach to Snell–Descartes reflections
Authors: BASKAR SAMBANDAM , COULOUVRAT FRANÇOIS , MARCHIANO RÉEGIS
Published: March 2007

We study the reflection of acoustic shock waves grazing at a small angle over a rigid surface. Depending on the incidence angle and the Mach number, the reflection patterns are mainly categorized into two types, namely regular reflection and irregular reflection. In the present work, using the nonlinear KZ equation, this reflection problem is investigated for extremely weak shocks as encountered in acoustics. A critical parameter, defined as the ratio of the sine of the incidence angle and the square root of the acoustic Mach number, is introduced in a natural way. For step shocks, we recover the self-similar (pseudo-steady) nature of the reflection, which is well known from von Neumann's work. Four types of reflection as a function of the critical parameter can be categorized. Thus, we describe the continuous but nonlinear and non-monotonic transition from linear reflection (according to the Snell–Descartes laws) to the weak von-Neumann-type reflection observed for almost perfectly grazing incidence. This last regime is a new, one-shock regime, in contrast with the other, already known, two-shock (regular reflection) or three-shock (von Neumann-type reflection) regimes. Hence, the transition also resolves another paradox on acoustic shock waves addressed by von Neumann in his classical paper. However, step shocks are quite unrealistic in acoustics. Therefore, we investigate the generalization of this transition for N-waves or periodic sawtooth waves, which are more appropriate for acoustics. Our results show an unsteady reflection effect necessarily associated with the energy decay of the incident wave. This effect is the counterpart of step-shock propagation over a concave surface. For a given value of the critical parameter, all the patterns categorized for the step shock may successively appear when the shock is propagating along the surface, starting from weak von-Neumann-type reflection, then gradually turning to von Neumann reflection and finally evolving into nonlinear regular reflection. This last one will asymptotically result in linear regular reflection (Snell–Descartes). The transition back to regular reflection is one of two types, depending on whether a secondary reflected shock is observed. The latter case, here described for the first time, appears to be related to the non-constant state behind the incident shock, which prevents secondary reflection.
Particle motion near and inside an interface
Authors: POZRIKIDIS C.
Published: March 2007

The motion of a spherical particle near the interface between two immiscible viscous fluids undergoing simple shear flow is considered in the limit of small Reynolds and capillary numbers where the interface exhibits negligible deformation. Taking advantage of the rotational symmetry of the boundaries of the flow with respect to the axis that is normal to the interface and passes through the particle centre, the problem is formulated as a system of one-dimensional integral equations for the first Fourier coefficients of the unknown components of the traction and velocity along the particle and interface contours. The results document the particle translational and angular velocities, and reveal that the particle slips while rolling over the interface under the influence of a simple shear flow, for any viscosity ratio. In the second part of the investigation, the motion of an axisymmetric particle straddling a planar interface is considered. The results confirm a simple exact solution when a particle with top-down symmetry is immersed half-way in each fluid and translates parallel to the interface, reveal a similar simple solution for a particle that is held stationary in simple shear flow, and document the force and torque exerted on a spherical particle for more general arrangements. The onset of a non-integrable singularity of the traction at the contact line prohibits the computation of the translational and angular velocities of a freely suspended particle convected under the action of a shear flow.
Exact scaling laws and the local structure of isotropic magnetohydrodynamic turbulence
Authors: YOUSEF T. A. , RINCON F. , SCHEKOCHIHIN A. A.
Published: March 2007

This paper examines the consistency of the exact scaling laws for isotropic magnetohydrodynamic (MHD) turbulence in numerical simulations with large magnetic Prandtl numbersPmand withPm= 1. The exact laws are used to elucidate the structure of the magnetic and velocity fields. Despite the linear scaling of certain third-order correlation functions, the situation is not analogous to the case of Kolmogorov turbulence. The magnetic field is adequately described by a model of a stripy (folded) field with direction reversals at the resistive scale. At currently available resolutions, the cascade of kinetic energy is short-circuited by the direct exchange of energy between the forcing-scale motions and the stripy magnetic fields. This non-local interaction is the defining feature of isotropic MHD turbulence.
Asymptotic theory of inertial convection in a rotating cylinder
Authors: ZHANG KEKE , LIAO XINHAO , BUSSE F. H.
Published: March 2007

Inertial convection in a fluid contained in a rotating cylinder heated uniformly from below is investigated on the basis of the assumption that convection at leading order can be represented by a single or several inertial wave modes which propagate either in the prograde or retrograde direction. Buoyancy forces appear at the next order to drive inertial convection against the effect of viscous damping. Asymptotic expressions for inertial convection for four different combinations of the sidewall boundary condition are derived for a cylinder of arbitrary aspect ratio. New convection patterns in rotating cylinders are revealed by the asymptotic analysis. A fully numerical solution of the same problem is also carried out, demonstrating a quantitative agreement between the asymptotic and numerical analysis.
The flow structure of a bubble-driven liquid-metal jet in a horizontal magnetic field
Authors: ZHANG C. , ECKERT S. , GERBETH G.
Published: March 2007

Static magnetic fields are known to be suitable for damping mean flow and turbulent motion in an electrically conducting liquid. In this paper, an experimental study is presented considering the influence of a horizontal magnetic field on a bubble-driven flow of a liquid metal. The investigation is focused on the liquid circulation inside a liquid metal column driven by a central jet produced by gas injection. The fluid vessel has a circular cross-section and electrically insulating walls. Low gas flow rates were applied, resulting in a plume of separated bubbles rising inside a spot around the cylinder axis. This axisymmetric configuration is exposed to a horizontal magnetic field. We present detailed experimental data describing the spatial as well as the temporal structure of the velocity field. Measurements of the vertical and the radial velocity component, respectively, were performed using the ultrasound Doppler velocimetry (UDV), allowing for the first time a complete mapping of the liquid velocity distribution for a bubble-driven liquid metal flow. The magnetic field considerably modified the global and local properties of the flow field compared to an ordinary bubble plume. In the parameter range considered here we did not find a prior flow suppression, but, in fact, a restructuring of the convective motion. The original axisymmetric flow field became anisotropic with respect to the direction of the magnetic field lines. An upwards flow dominated in a plane parallel to the magnetic field, whereas the recirculating motion was enforced in the orthogonal plane. Contrary to usual expectations, the application of a moderate magnetic field (100 < Ha < 400, 1 ≲ N ≲ 10) destabilizes the global flow and gives rise to transient, oscillating flow patterns with predominant frequencies.
Granular column collapses: further experimental results
Authors: THOMPSON ERICA L. , HUPPERT HERBERT E.
Published: March 2007

Experimental observations of the collapse of initially static columns of sand in axisymmetric and two-dimensional geometries are presented. The experiments were carried out using cylinders and rectangular tanks 30 to 60 cm tall, and cover aspect ratios between 0.5 and 20, where the aspect ratio is defined as the ratio of the initial height to horizontal extent of the column. The final positions of sand grains from different points initially on the outer surface of the columns are mapped. For all axisymmetric columns the point of maximum runout is found to originate from a point at fractional height 0.74 ± 0.03 of the initial vertical height of the column, independent of the aspect ratio. For two-dimensional columns the corresponding point is 0.65 ± 0.07. Collapses of columns of water-saturated sand into water display a different form of flow, which leads to there being no such well-defined point. In this case, grains from all but the innermost, basal areas of the initial column can end up in the outermost region of the final deposit. For collapses in air and aspect ratios greater than 1, the detail of the initial geometry is relatively insignificant in determining the shape of the final deposit. The results of this and previous studies thus have general applicability, even to situations with less initial symmetry. Movies are available with the online version of the paper.
Extra-adrenal regeneration of glucocorticoids by 11β-hydroxysteroid dehydrogenase type 1: physiological regulator and pharmacological target for energy partitioning
Authors: Walker Brian R.
Published: March 2007

The major glucocorticoid in man, cortisol, plays important roles in regulating fuel metabolism, energy partitioning and body fat distribution. In addition to the control of cortisol levels in blood by the hypothalamic–pituitary–adrenal axis, intracellular cortisol levels within target tissues can be controlled by local enzymes. 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyses the regeneration of active cortisol from inert cortisone, thereby amplifying cortisol levels and glucocorticoid receptor activation in adipose tissue, liver and other tissues. 11β-HSD1 is under complex tissue-specific regulation and there is evidence that it adjusts local cortisol concentrations independently of the plasma cortisol concentrations, e.g. in response to changes in diet. In obesity 11β-HSD1 mRNA and activity in adipose tissue are increased. The mechanism of this up-regulation remains uncertain; polymorphisms in the HSD11B1 gene have been associated with metabolic complications of obesity, including hypertension and type 2 diabetes, but not with obesity per se. Extensive data have been obtained in mice with transgenic over-expression of 11β-HSD1 in liver and adipocytes, targeted deletion of 11β-HSD1, and using novel selective 11β-HSD1 inhibitors; these data support the use of 11β-HSD1 inhibitors to lower intracellular glucocorticoid levels and treat both obesity and its metabolic complications. Moreover, in human subjects the non-selective ‘prototype’ inhibitor carbenoxolone enhances insulin sensitivity. Results of clinical studies with novel potent selective 11β-HSD1 inhibitors are therefore eagerly awaited. The present article focuses on the physiological role of glucocorticoids in regulating energy partitioning, and the evidence that this process is modulated by 11β-HSD1 in human subjects.
Nutritional interventions in critical illness
Authors: Powell-Tuck Jeremy
Published: March 2007

The metabolism of critical illness is characterised by a combination of starvation and stress. There is increased production of cortisol, catecholamines, glucagon and growth hormone and increased insulin-like growth factor-binding protein-1. Phagocytic, epithelial and endothelial cells elaborate reactive oxygen and nitrogen species, chemokines, pro-inflammatory cytokines and lipid mediators, and antioxidant depletion ensues. There is hyperglycaemia, hyperinsulinaemia, hyperlactataemia, increased gluconeogenesis and decreased glycogen production. Insulin resistance, particularly in relation to the liver, is marked. The purpose of nutritional support is primarily to save life and secondarily to speed recovery by reducing neuropathy and maintaining muscle mass and function. There is debate about the optimal timing of nutritional support for the patient in the intensive care unit. It is generally agreed that the enteral route is preferable if possible, but the dangers of the parenteral route, a route of feeding that remains important in the context of critical illness, may have been over-emphasised. Control of hyperglycaemia is beneficial, and avoidance of overfeeding is emphasised. Growth hormone is harmful. The refeeding syndrome needs to be considered, although it has been little studied in the context of critical illness. Achieving energy balance may not be necessary in the early stages of critical illness, particularly in patients who are overweight or obese. Protein turnover is increased and N balance is often negative in the face of normal nutrient intake; optimal N intakes are the subject of some debate. Supplementation of particular amino acids able to support or regulate the immune response, such as glutamine, may have a role not only for their potential metabolic effect but also for their potential antioxidant role. Doubt remains in relation to arginine supplementation. High-dose mineral and vitamin antioxidant therapy may have a place.
Nutrition interventions in women in low-income groups in the UK
Authors: Anderson Annie S.
Published: March 2007

In the UK the mental and physical health and well-being of millions of women are influenced by living in poverty. Low educational attainment, unemployment, low pay and poor areas of residence exacerbate the challenges of obtaining optimal food choices, dietary intake and healthy eating patterns. Poorer women are more likely to eat low amounts of fruits and vegetables, whole grains and fish, and higher amounts of sugar and sweetened drinks compared with more affluent women. Diet contributes to the health inequalities evident in high rates of diet-related morbidity (including obesity) and mortality (including IHD and stroke) and in maternal and child health considerations (including breast-feeding and family diet practices). There is a dearth of research on effective interventions undertaken with low-income women, reflecting some of the challenges of engaging and evaluating programmes with this ‘hard to reach’ subpopulation. Intervention programmes from the USA, including WISEWOMAN, the Women's Health Initiative, the American Special Supplemental Food Program for Women, Infants and Children and the Expanded Food and Nutrition Education Program provide models for changing behaviour amongst women in the UK, although overall effects of such programmes are fairly modest. Lack of evidence does not mean that that policy work should be not be undertaken, but it is essential that policy work should be evaluated for its ability to engage with target groups as well as for the behavioural change and health outcomes.
Selected research on second-language teaching and acquisition published in Japan in the years 2000–2006
Authors: Cornwell Steve , Simon-Maeda Andrea , Churchill Eton
Published: March 2007

This review presents selected research on language education published in English in Japan from 2000 to 2006. In an attempt to show the academic diversity and intellectual depth of current research agendas in Japan, it looks at the following areas: LANGUAGE POLICY, in which recent government mandates are outlined, including a stronger focus on English education in elementary school; TEAM-TEACHING situations that are commonly found at the high school and junior high school level; TESTING and PLACEMENT, focusing on entrance exams and placement exams which can be a driving force behind many classroom practices and continue to be the focus of considerable criticism; BILINGUALISM, which is receiving more and more attention in Japan as the number of returnees, children of bi-cultural families and other English-speaking Japanese nationals increases; WORLD ENGLISHES, reflecting the reality that many adult Japanese speakers of English interact with speakers from Outer and Expanding Circle countries; INTERLANGUAGE PRAGAMATICS, which is attracting more and more researchers interested in cross-cultural differences and interlanguage development; MOTIVATION, which continues to receive a great deal of attention and has been examined in a more nuanced approach of late; WRITING, in light of its importance in many educational settings; and GENDER and its interconnectedness to EFL learning and use.
Constructive analysis, types and exact real numbers
Authors: GEUVERS HERMAN , NIQUI MILAD , SPITTERS BAS , WIEDIJK FREEK
Published: March 2007

In this paper we will discuss various aspects of computable/constructive analysis, namely semantics, proofs and computations. We will present some of the problems and solutions of exact real arithmetic varying from concrete implementations, representation and algorithms to various models for real computation. We then put these models in a uniform framework using realisability, which opens the door to the use of type theoretic and coalgebraic constructions both in computing and reasoning about these computations. We will indicate that it is often natural to use constructive logic to reason about these computations.
A monadic, functional implementation of real numbers
Authors: ÓCONNOR RUSSELL
Published: March 2007

Large scale real number computation is an essential ingredient in several modern mathematical proofs. Because such lengthy computations cannot be verified by hand, some mathematicians want to use software proof assistants to verify the correctness of these proofs. This paper develops a new implementation of the constructive real numbers and elementary functions for such proofs by using the monad properties of the completion operation on metric spaces. Bishop and Bridges's notion (Bishop and Bridges 1985) of regular sequences is generalised to what I call regular functions, which form the completion of any metric space. Using the monad operations, continuous functions on length spaces (which are a common subclass of metric spaces) are created by lifting continuous functions on the original space. A prototype Haskell implementation has been created. I believe that this approach yields a real number library that is reasonably efficient for computation, and still simple enough to verify its correctness easily.
The impact of maternal employment on breast-feeding duration in the UK Millennium Cohort Study
Authors: Hawkins Summer Sherburne , Griffiths Lucy Jane , Dezateux Carol ,   Catherine Law and the Millennium Cohort Study Child Health Group
Published: March 2007

Objective

To examine the relationship of maternal employment characteristics, day care arrangements and the type of maternity leave pay to breast-feeding for at least 4 months.

Design

Cohort study.

Setting

Babies aged 9 months in the Millennium Cohort Study, born between September 2000 and January 2002.

Subjects

A total of 6917 British/Irish white employed mothers with singleton babies.

Results

Mothers employed part-time or self-employed were more likely to breast-feed for at least 4 months than those employed full-time (adjusted rate ratio (aRR) and 95% confidence interval (CI) 1.30 (1.17–1.44) and 1.74 (1.46–2.07), respectively). The longer a mother delayed her return to work postpartum, the more likely she was to breast-feed for at least 4 months (Pfor trend < 0.001). Mothers were less likely to breast-feed for at least 4 months if they returned to work for financial reasons (aRR 0.86, 95% CI 0.80–0.93) or used informal day care arrangements rather than care by themselves or their partner (aRR 0.81, 95% CI 0.71–0.91). Mothers were more likely to breastfeed for at least 4 months if their employer offered family-friendly (aRR 1.14, 95% CI 1.02–1.27) or flexible work arrangements (aRR 1.24, 95% CI 1.00–1.55), or they received Statutory Maternity Pay (SMP) plus additional pay during their maternity leave rather than SMP alone (aRR 1.13, 95% CI 1.02–1.26). These findings were independent of confounding factors, such as socio-economic status and maternal education.

Conclusions

Current policies may encourage mothers to enter or return to employment postpartum, but this may result in widening inequalities in breast-feeding and persistence of low rates. Policies should aim to increase financial support and incentives for employers to offer supportive work arrangements.
Adjusted population attributable fractions and preventable potential of risk factors for childhood obesity
Authors: Toschke André Michael , Rückinger Simon , Böhler Eva , Von Kries Rüdiger
Published: March 2007

Objective

A number of individual risk factors for childhood obesity have been identified, but only some of these are amenable to prevention. To assess the amount of cases in a general population attributable to these risk factors, adjusted population-attributable fractions were estimated.

Design

Cross-sectional study.

Setting

Obligatory school entry examination in 2001/2002 in six Bavarian communities (Germany).

Subjects

5472 children at age 5–6 years.

Measures

Anthropometric measures were ascertained by public health nurses, and measures concerning sociodemographics, lifestyle and child behaviour such as child's daily meal frequency were obtained with self-administered parental questionnaires. Obesity was defined according to sex- and age-specific body mass index cut-off points proposed by the International Obesity Task Force. Adjusted population-attributable fractions were calculated based on logistic regression.

Results

A combination of the risk factors low meal frequency, decreased physical activity, watching television >1 h day− 1, formula feeding and smoking in pregnancy accounted for 48.2% of obese children. This combination yielded a maximal achievable prevalence reduction of 1.5% for obesity (3.2% observed prevalence).

Conclusions

A modification of five known risk factors for childhood overweight and obesity could reasonably lower obesity prevalences at school entry. These risk factors should be particularly considered in decision making on preventive measures.
Autoantikörper – physiologisches Phänomen oder Ausdruck von Krankheit?
Authors: Trendelenburg
Published: March 2007

Mit zunehmendem Alter kann man in der Normalbevölkerung einen Anstieg der Prävalenz von Autoantikörpern beobachten, ohne dass dieser mit einem Anstieg der Häufigkeit von Autoimmunerkrankungen assoziiert ist. Dieses Phänomen betrifft eine Vielzahl verschiedener Autoantikörper und ist geschlechtsunabhängig. Die Ursache liegt vermutlich in einer Immunfehlregulation, die im Rahmen des komplexen Alterungsprozesses des Immunsystems entstehen kann. Das alleinige Vorhandensein von Autoantikörper reicht offenbar nicht aus, um eine Autoimmunerkrankung zu verursachen, jedoch stellt es wahrscheinlich einen Autoimmunrisiko-Phänotyp dar, auf dessen Boden durch zusätzliche Trigger Krankheit entstehen kann.
69-jährige Patientin mit unklarem zerebralen Krampfanfall
Authors: Riediger  , Iff  , Stucki  , Stanga
Published: March 2007

Erkrankungen, welche mit einem Vitamin-B12-Mangel einhergehen, sind neben hämatologischen Veränderungen durch verschiedenartige neurologische Symptome gekennzeichnet. Zu diesen Erkrankungen zählen sowohl hereditäre als auch sekundär erworbene Erkrankungen, die sich oft erst im mittleren bis späten Erwachsenenalter manifestieren. In unterschiedlicher Ausprägung können peripheres Nervensystem, Rückenmark und das zentrale Nervensystem durch pathologische Stoffwechselprozesse beeinträchtigt werden. Wir diskutieren den möglichen Zusammenhang von sekundärem Vitamin-B12-Mangel und epileptischen Anfällen anhand eines Fallbeispiels. Bei älteren Patienten, die erstmalig epileptische Anfälle erleiden, sollte man auch an einem Vitamin-B12-Mangel denken.
SAR/InSAR observation by an HF sounder
Authors: Kobayashi T. , Ono T.
Published: March 2007

Application of SAR imaging algorithm to spaceborne HF sounder observation was studied. Two types of image ambiguity problems were addressed in the application. One is surface/subsurface image ambiguity arising from deep penetration of HF wave, and another is mirror image ambiguity that is inherent to dipole antenna SAR. A numerical model demonstrated that the surface/subsurface ambiguity can be mitigated by taking a synthetic aperture large enough to defocus subsurface objects. In order to resolve the mirror image ambiguity problem, an image superposition technique was proposed. The performance of the technique was demonstrated by using simulation data of the HF sounder observation to confirm the feasibility of HF SAR and HF InSAR observation.
Draft changes issued on key U.S. environmental law
Authors: Zielinski Sarah
Published: March 2007

A U.S. Congressional task force proposed 22 changes to the National Environmental Policy Act in a draft report issued on 21 December 2005 (see Eos 86(48), 2005).

The changes include redefining what is a ‘major federal action’ under the law and, thus, subject to NEPA review. In addition, the report would modify the public participation process so that local groups and individuals have more influence, and restrict who can bring lawsuits under NEPA.
Australian university proposes academic program changes
Authors: Zielinski Sarah
Published: March 2007

The University of Melbourne in Australia has adopted a 10‐year plan to create a U.S.‐style of education where undergraduate university students would first have to complete a three‐year general degree in science or the arts before being allowed to continue onto graduate or professional studies. Unlike in the United States, most Australian students are able to move from secondary school directly into professional studies.

A major change for Earth science students would be the replacement of the one‐year Bachelor of Science Honours with a two‐year Masters program. According to Janet Hergt, head of the university's School of Earth Sciences, the longer program could allow students more time to develop and complete research projects, and would provide them with a better understanding of Ph.D.studies.
Ocean drilling vessel gets overhaul
Authors: Zielinski Sarah
Published: March 2007

After 20 years of ocean drilling, the research vessel JOIDES Resolution is getting a complete overhaul, including a new name, before it goes back into service in mid‐2007.

A 50 percent increase in laboratory space and the addition of new instrumentation will allow scientists to analyze core samples onboard. Improvements to the drilling system and the ship's hull and machinery will increase both the rate at which cores can be obtained and their quality. Scientists and crew will also benefit from a renovation of the staterooms, which will be expanded to accommodate 23 additional people.
Correction [to “NASA terminates two Earth observation missions”]
Authors: Anonymous
Published: March 2007

In the news article “NASA Terminates Two Earth Observation Missions” in the 24 January 2006 issue of Eos (Eos (87)4,2006), a remark by Richard Anthes, president of the University Corporation for Atmospheric Research, Boulder, Colo., was misinterpreted. It should have read,“Anthes said the termination of Hydros and the delay in the release of the next ESSP announcement ‘means that [Hydros] is indefinitely delayed at best and, at worst, it is dead.’”
Census of coral reef ecosystems
Authors: Kumar Mohi
Published: March 2007

Three oceanographic institutions are collaborating to conduct a global census of coral reef ecosystems in order to evaluate species abundances and their vulnerabilities to human stressors, the groups announced on 23 January

This project, called CReefs, is managed by the Scripps Institution of Oceanography, the Australian Institute of Marine Science, and the Pacific Islands Fisheries Science Center of the U.S. National Oceanic and Atmospheric Administration.
NASA science programs lack money and balance
Authors: Zielinski Sarah
Published: March 2007

NASA should restore funding for smaller science missions, research and analysis (R & A) programs, and technology for future missions, according to a report released on 4 May by the U.S. National Academies' National Research Council.
NASA's Genesis crash blamed on design flaw
Authors: Zielinski Sarah
Published: March 2007

NASA's Genesis spacecraft was launched in 2001 with the mission of returning samples of solar wind particles to Earth, but the return capsule's parachute did not deploy, and the capsule crashed into the Utah desert on 8 September 2004. That crash now can be attributed to a design flaw, according to a report released on 13 June.

An investigation into the incident revealed that a sensor was inverted during the design process, and this design flaw was not detected by several review processes. Because of the flaw in the sensor, the sample return capsule was unable to sense its deceleration as it descended through the atmosphere and did not deploy its parachute.
Academy seeks nominations for oceanography prize
Authors: Anonymous
Published: March 2007

The U.S. National Academy of Sciences (NAS) is seeking nominations for the 2007 Alexander Agassiz Medal.The medal and $15,000 prize honors an original contribution to the science of oceanography.

Nominees are welcome from anywhere in the world, and NAS membership is not required to either submit a nomination or be nominated.
Sound Images of the Ocean in Research and Monitoring
Authors: Coffin Mike
Published: March 2007

Call me Moby. The dream of every marine acoustician and seismologist is to image the ocean, the seafloor, and the subseafloor from the perspective of a whale's ear or, if the abyss weren't utterly dark, a fish's eye.

Peter Wille's ambitious and remarkable, yet idiosyncratic compilation of sound translated into visual images of the ocean realm is perhaps the next best thing. The meat of the volume and accompanying CD‐ROM consists of 452 mostly fascinating, mostly color images, all helpfully indexed at the start of the book, representing the contributions of more than 120 scientists from 22 nations. Those latter two numbers produce shudders and tics, if not migraines, in anyone who's ever assembled a volume involving contributions from even an order of magnitude fewer contributors.
Witnesses urge Law of Sea ratification
Authors: Zielinski Sarah
Published: March 2007

To better manage the nations oceans, the United States should establish a national ocean policy and ratify the United Nations Convention on the Law of the Sea, several witnesses testified at a 3 August hearing before the Senate Commerce, Science, and Transportation Subcomittee on National Ocean Policy Study.

“Our oceans are in crisis,” said Leon Panetta, co‐chair of the Joint Ocean Commission Initiative. Panetta cited several issues threatening oceans, including ocean acidification, increasing amounts of pollution, lost wetlands, depleted fisheries, invasive species, and a fragmented U.S. governance system.
Strategic approach needed for atmospheric research
Authors: Zielinki Sarah
Published: March 2007

The Division of Atmospheric Sciences (ATM) within the U.S. National Science Foundation should develop a strategic plan in concert with the atmospheric science community and should regularly seek guidance from a panel of representatives of that community to ensure that the community's needs are met, according to a recent report from a committee of the U.S. National Research Council of the U.S. National Academies. ATM also should encourage and guide scientists participating in cross‐disciplinary research and research that crosses federal agencies as well as increase support for high‐risk, potentially transformative research. The committee also recommended the formation of a new graduate fellowship program.
Scientific drilling project on Russia's Mutnovsky Volcano
Authors: Eichelberger John , Kiryukhin Alexey
Published: March 2007

What is the relationship between volcanoes that ring the Pacific plate and hydrothermal systems? A typical geometry consists of a stratovolcano or dome complex with fumaroles at the summit and hydrothermal manifestations on its flank. Analogous subsurface mineralization is porphyry copper deposits flanked by shallow copper‐silver‐gold acid‐sulfate deposits and base metal veins.

Possible reasons for this association are (1) flow of magmatic gas and heat from the volcano's conduit mixing with meteoric water; (2) dikes extending from or feeding toward the volcano that extend well beyond the surface edifice; or (3) peripheral hot intrusions that are remnants of previous volcanic episodes and unrelated to current volcanism.
Reply to Comment on “Bathymetric survey images structure off Sumatra”
Authors: Ladage Stefan
Published: March 2007

As we understand the comment by J. N. Murdock on our article “Bathymetric survey images structure off Sumatra,” he wishes to point out that in our ongoing studies of the western Sumatra margin, we should consider an unconventional “blind thrust model” instead of a “megathrust model.”

First, we would like to remark that we reported on new bathymetric data, which by itself does not allow for interpretation of deep‐seated subsurface structures. A discussion on megathrusting or not at the plate interface is beyond the scope of our article. We would further like to point out that in what Murdock calls a “conventional plate model of convergence,” blind thrusts are actually common features and known from accretionary prisms worldwide. In fact, many of the folds visible in the bathymetry offshore Sumatra will have developed above blind thrusts, especially the younger ones where the thrusts have not yet propagated through the core of the anticline up to the seafloor.
Evolution of a man‐made plume in coastal waters
Authors: Steinmaus Karen L. , Bowles Jeffrey , Woodruff Dana , Donato Timothy , Rhea William J. , Snyder William , Korwan Dan , Miller Lee , Petrie Greg , Maxwell Adam R. , Hibler Lyle
Published: March 2007

The ability to understand the biogeophysical parameters that create ocean color in coastal waters is fundamental to exploiting remote sensing for coastal applications. The apparent color, which is the upwelling radiance of large water bodies is determined by the absorption and scattering of light caused by the water, the organic and inorganic material contained in the water, and the bottom, when the albedo is high enough and the water is shallow enough.

Bio‐optical oceanography measures and models the interaction of the light field with the biological and nonbiological constituents of natural waters. One goal of optical oceanography is to be able to use measured radiance to identify and quantify water constituents, referred to as inherent optical properties (IOPs). Linking optical properties with measured water quality parameters often is made through radiative transfer models, in which the light field is modeled through the water and all of its constituents. This modeling is done to evaluate optical closure, which is the ability to accurately predict the upwelling radiance resulting from a known set of constituents.
Web site access to Earth observation imagery
Authors: Zielinki Sarah
Published: March 2007

The European Space Agency has made imagery from its Earth observation satellite Envisat freely available to the public through a new Web site (http://www.esa.int/miravi).The site, MIRAVI, which is short for MERIS (Medium Resolution Imaging Spectrometer) Images Rapid Visualization, generates images from the data collected by the MERIS optical instrument. The images then are placed on the site within two hours of acquisition. Images archived through May 2006 also are available and searchable by date.
Ocean research plan reviewed
Authors: Zielinski Sarah
Published: March 2007

A draft plan setting out priorities for U.S. ocean research generally was lauded for its clear and well‐articulated view in a recent report from a committee of the U.S. National Research Council (NRC) of the US. National Academies. However, the committee advised that the plan would benefit from a bold vision for the future of ocean science research, additional details, and a reorganization to include cross‐cutting research.

The draft “Charting the Course for Ocean Science in the United States: Research Priorities for the Next Decade” was made available for public comment in September 2006 by the U.S. National Science and Technology Council's Joint Subcommittee on Ocean Science and Technology.
The historic fur trade and climate change
Authors: Varekamp Johan C.
Published: March 2007

Why did the Dutch come to the North American shores 400 years ago? Was it wanderlust, expansionist policies, or simply money? The earliest western explorers were the Vikings who, in the 1100s, were able to sail beyond Iceland and Greenland to Newfoundland, because they did so during the Medieval Warm Period. English explorer Henry Hudson, on the other hand, could not find a northern passage to China because the early 1600s were the coldest part of the Little Ice Age and the northern seas were frozen over (Figure 1).

After Hudson's third voyage, Dutch merchants contracted several sailors to establish trading posts for beaver pelts in the Americas. Among them was Adriaen Block, who built the first western settlement on the island of Manhattan (New York) after a fire on his ship forced him to over‐winter there in 1614 [Varekamp and Varekamp, 2006]. His 1614 ‘figurative map’ shows Long Island Sound as an estuary, and introduced for the first time the name ‘Niew Nederlandt’ (New Netherlands).
20th century changes in surface solar irradiance in simulations and observations
Authors: Romanou A. , Liepert B. , Schmidt G. A. , Rossow W. B. , Ruedy R. A. , Zhang Y.
Published: March 2007

The amount of solar irradiance reaching the surface is a key parameter in the hydrological and energy cycles of the Earth's climate. We analyze 20th Century simulations using nine state‐of‐the‐art climate models and show that all models estimate a global annual mean reduction in downward surface solar radiation of 1–4 W/m2 at the same time that the globe warms by 0.4–0.7°C. In single forcing simulations using the GISS‐ER model, this “global dimming” signal is shown to be predominantly related to aerosol effects. In the global mean sense the surface adjusts to changes in downward solar flux instantaneously by reducing the upward fluxes of longwave, latent and sensible heat. Adding increased greenhouse gas forcing traps outgoing longwave radiation in the atmosphere and surface which results in net heating (although reduced) that is consistent with global warming over the 20th Century. Over the 1984–2000 period, individual model simulations show widely disparate results, mostly related to cloud changes associated with tropical Pacific variations, similar to the changes inferred from the satellite data analysis. This suggests that this time period is not sufficient to determine longer term trends.
Latitudinal variations of cloud and aerosol optical thickness trends based on MODIS satellite data
Authors: Kishcha Pavel , Starobinets Boris , Alpert Pinhas
Published: March 2007

Moderate Resolution Imaging Spectroradiometer (MODIS) global monthly data from the Terra satellite (MOD08_M3, Collection 4, from March 2000 to May 2006) indicated, with the exception of the tropics, declining trends in aerosol optical thickness (AOD) over much of the globe, in contrast to slightly increasing trends in cloud optical thickness (COT) at many latitudes. In the tropics, increasing AOD trends coincide with increasing COT trends. In the latitudinal distribution of COT, in the Northern Hemisphere, a transition from increasing to declining tendencies was observed between 40°N and 60°N. There is a pronounced hemispheric asymmetry in latitudinal variations of the averaged total AOD, in contrast to those of the averaged total COT.
Triggering of earthquakes during the 2000 Papua New Guinea earthquake sequence
Authors: Park Sun‐Cheon , Mori Jim
Published: March 2007

A sequence of large earthquakes occurred in the New Britain/New Ireland region of Papua New Guinea in late 2000. The sequence started with a Mw 6.8 earthquake along the New Britain Trench on 29 October. About 20 days later a Mw 8.2 earthquake occurred in the New Ireland region on 16 November and produced large strike‐slip surface displacements and tsunamis. Following the Mw 8.2 event, two large earthquakes (Mw ∼ 7.5) occurred along the nearby New Britain Trench on 16 and 17 November. Furthermore, small triggered events were observed over a wide area outside of the rupture zones of the large earthquakes, with different focal mechanisms from those of the major events. There is likely some mechanism(s) that triggered this remarkable sequence, and we document the details of the spatial and temporal patterns of the events. We investigated if static stress changes can explain the initiation of the large earthquakes and also some groups of triggered smaller events. There are mixed results. The occurrences of the two M ∼ 7.5 major events may be explained by the static stress changes; however, there are also some earthquakes that are not consistent with triggering by static stress changes. There may be multiple mechanisms, including static and dynamic stress changes, that are needed to explain the complicated sequence of earthquakes.
Model smoothing strategies to remove microscale discontinuities and spurious secondary optima in objective functions in hydrological calibration
Authors: Kavetski Dmitri , Kuczera George
Published: March 2007

Environmental processes frequently exhibit threshold‐type behavior, e.g., the initiation of fluxes such as snowmelt, recharge, and quick flow. Incorporating such thresholds into hydrological models introduces discontinuities into the objective functions used in model calibration, making parameter estimation unnecessarily more difficult. Moreover, this study shows that model thresholds can produce spurious multimodality in least squares objective functions even if the underlying model is near linear in its parameters. In contrast, smoothing the model with respect to its parameters and inputs yields differentiable objective functions and, in some cases, can also improve its macroscale characteristics by removing spurious secondary optima. This simplifies model calibration and sensitivity analysis by reducing the complexity of objective functions and permitting the use of powerful derivative‐based analysis methods such as Newton‐type optimization and Hessian‐based uncertainty assessment. This paper details smoothing strategies for several classes of thresholds and discontinuities commonly found in hydrological models, including step and angle discontinuities in the constitutive functions and flux constraints arising from conservation laws in the governing differential equations. The smoothing algorithms and their parameters are selected to ensure infinite differentiability of the model and its objective functions while preserving the macroscale behavior of the original governing equations. The improvements in the structure of the model and its objective functions are illustrated empirically for a degree‐day‐based snow model. The smoothing techniques are general and can be applied to other models with thresholds.
Confinement of surface patterning in azo-polymer thin films
Authors: Yager Kevin G. , Barrett Christopher J.
Published: March 2007

Azobenzene polymer thin films are known to spontaneously generate surface patterns in response to incident light gradients. This peculiar process is investigated in terms of the dynamics of the various azobenzene photomotions, which occur on different length scales. In particular, the formation and thermal erasure of surface relief gratings are measured as a function of film thickness and by using combinatorial samples with thickness gradients. The thermal erasure of gratings in this system provides a direct measure of the glass-transition temperature, which is found to deviate substantially from the bulk value. Thin azo films exhibit a glass transition up to 50K higher than the bulk. These dynamical measurements allow the authors to probe the length scale of mass transport, which is found to be ∼150nm. Furthermore, surface mass transport is completely arrested in thin films <40nm. According to these results, mass transport involves the coordinated motion of many polymer chains in the depth of the sample, rather than surface diffusion of individual chains.
Time-resolved spectroscopy of silver nanocubes: Observation and assignment of coherently excited vibrational modes
Authors: Petrova Hristina , Lin Chien-Hua , de Liejer Suzanna , Hu Min , McLellan Joseph M. , Siekkinen Andrew R. , Wiley Benjamin J. , Marquez Manuel , Xia Younan , Sader John E. , Hartland Gregory V.
Published: March 2007

The response of single crystal, cubic silver particles to ultrafast laser-induced heating has been examined experimentally and theoretically. The transient absorption traces display clear modulations due to coherently excited vibrational modes. Nanocube samples with edge lengths smaller than 50nm show a single modulation, whereas samples larger than 50nm show two vibrational modes. The results are compared to finite element calculations, where the cubes are modeled as having cubic crystal symmetry with the principal axes parallel to the sides of the particle. The action of the laser pulse is treated in two ways, first, as creating a uniform initial strain. In this case the predominant mode excited is the breathing mode. The period of this mode is in reasonable agreement with the vibrational periods measured for the smaller cubes and with the higher frequency modulation observed for the larger cubes. A nonuniform initial strain is also considered, which could arise from nonuniform heating for particles larger than the optical skin depth of the metal. In this case the predominant mode excited is a nontotally symmetric mode. The calculated periods from this analysis are in reasonable agreement with the lower frequency modulations observed for the larger samples. The results from this study show that, to within the accuracy of these measurements, the elastic constants of cubic silver nanoparticles are the same as bulk silver.
Gold nanoparticle multilayer films based on surfactant films as a template: Preparation, characterization, and application
Authors: Li Yancai , Zhou Ji , Zhang Kai , Sun Changqing
Published: March 2007

Highly ordered gold nanoparticle multilayer films were achieved conveniently using didodecyldimethylammonium bromide (DDAB) films as a template. The template was produced by casting DDAB chloroform solution onto the surface of a (3-aminopropyl)trimethoxysilane-modified indium tin oxide substrate and then evaporating the organic solvent. Gold nanoparticle multilayer films were prepared by soaking the template in 2.6nm colloidal gold solution for 120min. The well-ordered superlattice structure of the DDAB template and the gold nanoparticle multilayer films was identified by x-ray diffraction. The characterizations of the gold nanoparticle multilayer films by UV-vis spectroscopy, atomic force microscopy, and cyclic voltammerty were described in detail. The application of the as-prepared gold nanoparticle multilayer films in surface-enhanced Raman spectroscopy (SERS) was investigated by using Rhodamine 6G as a probe molecule. It was found that the colloidal gold nanoparticle multilayer films exhibit remarkable enhancement ability and can be used as SERS substrates.