bluuebunny/crossref_metadata_2025 huggingface dataset:
Can Renminbi Appreciation Reduce the US Trade Deficit?
Authors: Zhang Jian , Fung Hung‐Gay , Kummer Donald
Published: September 2009

Using a computational general equilibrium model, we analyze the impacts of Chinese real exchange rate appreciation on the trade balance of China and the USA and on various industries of both countries. We use several scenarios with 2.1, 6 and 12 percent real exchange rate appreciations for our simulation analysis. The results indicate that China's exchange rate appreciation might not solve the enlarging US current account deficits. Chinese outputs in both primary and manufacture sectors will increase, whereas the outputs of energy and services sectors will be adversely affected. The price of value‐added products declines in light of the renminbi appreciation.

(Edited by Zhinan Zhang)
China's Large and Rising Net Foreign Asset Position
Authors: Ma Guonan , Zhou Haiwen
Published: September 2009

China's emergence as a major player in world trade is well known, but its growing role in global finance might have been underappreciated. China is the second largest creditor in the world today, with a net creditor position of 30 percent of GDP in 2008. We test the importance of the growth differential, demographics, government debt, financial depth and the exchange rate in shaping China's net foreign asset position. Our empirical results highlight the sharp fall in the young‐age dependence as one key driver behind China's puzzlingly large net lender position and also confirm the neoclassical prediction that faster growth attracts more capital inflows. Looking ahead, our findings suggest that China will unlikely turn into a meaningful net debtor nation over the next two decades.
From State to State: Quasi‐privatization and Firm Performance
Authors: Wang Kun
Published: September 2009

This paper uses a sample of Chinese listed companies whose controlling shareholders have changed from government agencies to state‐owned enterprises (SOEs), to examine whether reducing government intervention while maintaining government's ultimate control could improve firm performance. The results show that the overall performance of these firms improves after the transfer of their controlling shareholders, due to improvements in both operating and non‐operating performance. When we separate all samples into solely SOEs and other SOEs based on the controlling shareholder, we find that operating performance improved significantly in the solely SOE group, whereas non‐operating performance improved significantly in the SOE group. In addition, we identify sources of performance improvement from two perspectives: corporate governance and related party transactions. The results imply that the Chinese Government should continue to decentralize control and, at the same time, continue to monitor firm operating efficiency.
Empirical Analysis of Provincial Energy Efficiency in China
Authors: Wei Chu , Ni Jinlan , Shen Manhong
Published: September 2009

This paper proposes an energy efficiency index based on the data envelopment analysis approach. The index is used to examine energy efficiency in China. Using 1997–2006 panel data for 29 provinces, we find that energy efficiency is negatively associated with the secondary industry share in GDP, the state‐owned economic share in GDP and the government expenditure share in GDP, and is positively associated with the technical level and non‐coal share in energy consumption. In addition, we find that there exists a large gap in energy efficiency among eastern, central and western regions. The eastern region has a significantly higher energy efficiency level than the central and western regions. We conclude that the different levels of industry structure, government intervention, energy structure, and the technology content in the three regions lead to the differences in energy efficiency.
The Sociolinguistics of Ethnicity in Pittsburgh
Authors: Eberhardt Maeve
Published: September 2009

Recently, there has been a growing interest in regional variation within African American English. This study reviews a work done on local speech in Pittsburgh, Pennsylvania, discussing trends for both African American and White ethnic groups. Just as scholars have found in other geographic regions, in Pittsburgh, African Americans and Whites share a number of feature characteristics of the local dialect, but remain distinct in a number of other ways. Research in Pittsburgh, as elsewhere, highlights the complexity, rather than the homogeneity, of African American speech across the country, as speakers exhibit alignment to both regional and supraregional ethnic linguistic norms.
Computational Methods for Normalizing Acoustic Vowel Data for Talker Differences
Authors: Clopper Cynthia G.
Published: September 2009

Direct acoustic–phonetic comparison of vowels produced by different talkers can be difficult due to the effects of anatomical and physiological talker differences on first and second formant frequencies. Since the mid‐1960s, numerous computational algorithms have been proposed to normalize formant frequency measures and reduce the effects of talker‐specific variability. These algorithms vary widely in their conceptualization: some require samples of the entire vowel space (vowel extrinsic), whereas others can be conducted on a single vowel class (vowel intrinsic); some are based on a single‐scale factor to align broad classes of talkers (such as females and males), whereas others use scale factors and/or vowel space ranges for individual talkers to align their vowel systems in the same acoustic–phonetic space. In this study, an overview of the most commonly used normalization algorithms is provided and the advantages and disadvantages of each of the approaches are discussed.
Determination of Selenium Concentrations in NIST SRM 610, 612, 614 and Geological Glass Reference Materials Using the Electron Probe, LA‐ICP‐MS and SHRIMP II
Authors: Jenner Frances E. , Holden Peter , Mavrogenes John A. , O'Neill Hugh St.C. , Allen Charlotte
Published: September 2009

A combination of EMPA, sensitive high resolution ion microprobe (SHRIMP II) and/or LA‐ICP‐MS techniques was used to measure the concentration of selenium (Se) in NIST SRM 610, 612, 614 and a range of reference materials. Our new compiled value for the concentration of Se in NIST SRM 610 is 112 ± 2 μg g−1. The concentration of Se in NIST SRM 612, using NIST SRM 610 for calibration, determined using LA‐ICP‐MS (confirmed using SHRIMP II) was 15.2 ± 0.2 μg g−1. The concentration of Se in NIST SRM 614, using LA‐ICP‐MS was 0.394 ± 0.012 μg g−1. LA‐ICP‐MS determination of Se in synthetic geological glasses BCR‐2G, BIR‐1G, TB‐1G and the MPI‐DING glasses showed a range in concentrations from 0.062 to 0.168 μg g−1. Selenium in the natural glass, VG2, was 0.204 ± 0.028 μg g−1.
The “Ottawa syndrome”: The localization of federal public servants in Canada
Authors: Graham Katherine A.H. , Swimmer Gene
Published: September 2009

Abstract: This article examines the distribution of federal public servants across Canada and asks the question “Does the distribution of the federal public service across Canada matter in the formulation of federal policies related to municipalities?” The article takes a two‐part approach. First, it examines the history of and commentary on decentralization and de‐concentration of the federal public service. It then proceeds to examine the data on the distribution of federal employment over time and uses regression analysis to explain the variations in the relative federal employee presence across local areas and through time. Analysis of initiatives to reform the way in which the public service operates and of the data regarding the location of public servants across the country suggest that broad political, economic and regional factors influence the size and distribution of federal employment across the country, perhaps more than any conscious intent about improving the responsiveness of the federal public service to local conditions. At present, the “knowledge functions” of the federal government are concentrated in the National Capital Region. It is an open question whether this will serve the federal government and Canadians well in the future.

Sommaire : Cet article étudie la répartition des fonctionnaires fédéraux à travers le Canada et pose la question suivante : «Est‐ce que la répartition des fonctionnaires fédéraux au Canada a un rôle à jouer dans la formulation des politiques fédérales ayant trait aux municipalités?» L'article comporte une approche en deux parties. Dans la première, les auteurs examinent l'histoire et les commentaires sur la décentralisation et la déconcentration de la fonction publique fédérale. Ensuite, ils étudient les données sur la répartition des employés fédéraux au fil des années et se servent de l'analyse de régression pour expliquer les variations dans la présence relative des fonctionnaires fédéraux dans les secteurs municipaux et dans le temps. L'analyse des initiatives visant à réformer la manière dont la fonction publique fonctionne et des données concernant la localisation des fonctionnaires à travers le pays laisse entendre que d'importants facteurs politiques, économiques et régionaux influencent la taille et la répartition des emplois fédéraux à travers le pays, peut‐être plus que toute intention délibérée d'améliorer la réceptivité de la fonction publique fédérale aux conditions locales. À l'heure actuelle, les «fonctions de connaissance» du gouvernement fédéral sont concentrées dans la région de la capitale nationale. La question est de savoir si cela servira la cause du gouvernement fédéral et du peuple canadien à l'avenir.
Circulating bone‐marrow‐derived endothelial precursor cells contribute to neovascularization in diabetic epiretinal membranes
Authors: Abu El‐Asrar Ahmed M. , Struyf Sofie , Verbeke Hannelien , Van Damme Jo , Geboes Karel
Published: September 2009

Purpose: The role of vasculogenesis, recruitment and differentiation of circulating bone‐marrow‐derived endothelial precursor cells into mature endothelium in proliferative diabetic retinopathy (PDR) remains undefined. We investigated the presence of bone‐marrow‐derived endothelial precursor cells and the expression of the chemotactic pathway SDF‐1/CXCL12−CXCR4 in PDR epiretinal membranes.

Methods: Membranes from eight patients with active PDR and nine patients with inactive PDR were studied by immunohistochemistry using antibodies against CD133, vascular endothelial growth factor receptor‐2 (VEGFR‐2), CD14, SDF‐1 and CXCR4.

Results: Blood vessels expressed CD133, VEGFR‐2, CD14, SDF‐1 and CXCR4 in 10, 10, 10, seven and seven out of 17 membranes, respectively. There were significant correlations between number of blood vessels expressing CD34 and number of blood vessels expressing CD133 (rs = 0.646; p = 0.005), VEGFR‐2 (rs = 0.704; p = 0.002), CD14 (rs = 0.564; p = 0.018) and SDF‐1 (rs = 0.577; p = 0.015). Stromal cells in close association with blood vessels expressed CD133, VEGFR‐2, CD14 and CXCR4 in 10, 12, 13 and 14 membranes, respectively. The number of blood vessels expressing CD133 (p = 0.013), VEGFR‐2 (p = 0.005), CD14 (p = 0.008) and SDF‐1 (p = 0.005), and stromal cells expressing CD133 (p = 0.003), VEGFR‐2 (p = 0.013) and CD14 (p = 0.002) was significantly higher in active membranes than in inactive membranes.

Conclusion: Bone‐marrow‐derived CD133+endothelial progenitor cells and CD14+monocytes may contribute to vasculogenesis in PDR.
Assembly Configurations of Spatial Single-Loop Single-DOF Mechanisms
Authors: Foster David E. , Cipra Raymond J.
Published: September 2009

This paper examines the problem of finding the assembly configurations (ACs), also called circuits, of spatial single-loop single-DOF mechanisms. All six lower pairs are considered: revolute (R), cylindric (C), prismatic (P), helical (H), spheric (S), and planar (E). The RSSR, CSS, RRSC, CCS, and RRSRR mechanisms are covered, along with all variations in which an R joint is replaced with a P or H joint, or an S joint is replaced with an E joint. The RRCRC, RRRCC, and RRRRCR mechanisms are covered, along with all appropriate variations in which an R joint is replaced by a P or H joint. A numerical method is given to find the ACs, and is illustrated with several examples.
Optimal Splines for Rigid Motion Systems: A Convex Programming Framework
Authors: Demeulenaere B. , Pipeleers G. , De Caigny J. , Swevers J. , De Schutter J. , Vandenberghe L.
Published: September 2009

This paper develops a general framework to synthesize optimal polynomial splines for rigid motion systems driven by cams or servomotors. This framework is based on numerical optimization, and has three main characteristics: (i) Spline knot locations are optimized through an indirect approach, based on providing a large number of fixed, uniformly distributed candidate knots; (ii) in order to efficiently solve the corresponding large-scale optimization problem to global optimality, only design objectives and constraints are allowed that result in convex programs; and (iii) one-norm regularization is used as an effective tool for selecting the better (that is, having fewer active knots) solution if many equally optimal solutions exist. The framework is developed and validated based on a double-dwell benchmark problem for which an analytical solution exists.
Optimal Splines for Rigid Motion Systems: Benchmarking and Extensions
Authors: Demeulenaere B. , De Caigny J. , Pipeleers G. , De Schutter J. , Swevers J.
Published: September 2009

This paper illustrates the power and versatility of the convex programming framework for optimal spline synthesis that was developed in a companion paper (Demeulenaere, Pipeleers, De Caigny, Swevers, De Schutter, and Vandenberghe, 2009, “Optimal Spines for Rigid Motion Systems: A Convex Programming Framework”, ASME J. Mech. Des., 131, p. 101005.). Two case studies concerning rigid motion systems illustrate the ability of the framework to improve upon recent (2005) literature results: (i) a numerical optimization study concerning kinematic optimization of uniform quintic splines for cam systems and (ii) an analytical study concerning time optimal quartic splines for motion systems driven by servomotors and subject to kinematic constraints. In a third study, the versatility of the framework is illustrated by generating time optimal and time-energy optimal motions for a rigid servomotor driven system under torque constraints. Based on these three case studies, the convex programming framework of the companion paper is extended with the following generic aspects: (i) a bisection to generate time optimal motions, (ii) a direct expression of the upper and lower bounds on motor torque, and (iii) a convex quadratic energy objective function for servomotor driven systems.
The Optimization for the Shape Profile of the Slider Surface Under Ultra-Thin Film Lubrication Conditions by the Rarefied-Flow Model
Authors: Cheng Chin-Hsiang , Chang Mei-Hsia
Published: September 2009

The optimization of the surface shape for a slider to meet the specified load demands under an ultra-thin film lubrication condition has been performed in this study. The optimization process is developed based on the conjugate gradient method in conjunction with a direct problem solver, which is built based on the rarefied-flow theory. The direct problem solver is able to predict the pressure distributions of the rarefied gas flows in the slip-flow, transition-flow, and molecular-flow regimes with a wide range of characteristic inverse Knudsen number. First, the validity of the direct problem solver has been verified by a comparison with the existing information for some particular cases, and then the developed direct problem solver is incorporated with the conjugate gradient method for optimizing the shape profile of the slider surface. The performance of the present optimization approach has also been evaluated. Results show that the shape profile of the slider surface can be efficiently optimized by using the present approach. Thus, a number of cases under various combinations of influential parameters, involving the characteristic inverse Knudsen number and the bearing numbers in the x- and y-directions, are investigated.
An Investigation of the NOCSAE Linear Impactor Test Method Based on In Vivo Measures of Head Impact Acceleration in American Football
Authors: Gwin Joseph T. , Chu Jeffery J. , Diamond Solomon G. , Halstead P. David , Crisco Joseph J. , Greenwald Richard M.
Published: September 2009

The performance characteristics of football helmets are currently evaluated by simulating head impacts in the laboratory using a linear drop test method. To encourage development of helmets designed to protect against concussion, the National Operating Committee for Standards in Athletic Equipment recently proposed a new headgear testing methodology with the goal of more closely simulating in vivo head impacts. This proposed test methodology involves an impactor striking a helmeted headform, which is attached to a nonrigid neck. The purpose of the present study was to compare headform accelerations recorded according to the current (n=30) and proposed (n=54) laboratory test methodologies to head accelerations recorded in the field during play. In-helmet systems of six single-axis accelerometers were worn by the Dartmouth College men’s football team during the 2005 and 2006 seasons (n=20,733 impacts; 40 players). The impulse response characteristics of a subset of laboratory test impacts (n=27) were compared with the impulse response characteristics of a matched sample of in vivo head accelerations (n=24). Second- and third-order underdamped, conventional, continuous-time process models were developed for each impact. These models were used to characterize the linear head/headform accelerations for each impact based on frequency domain parameters. Headform linear accelerations generated according to the proposed test method were less similar to in vivo head accelerations than headform accelerations generated by the current linear drop test method. The nonrigid neck currently utilized was not developed to simulate sport-related direct head impacts and appears to be a source of the discrepancy between frequency characteristics of in vivo and laboratory head/headform accelerations. In vivo impacts occurred 37% more frequently on helmet regions, which are tested in the proposed standard than on helmet regions tested currently. This increase was largely due to the addition of the facemask test location. For the proposed standard, impactor velocities as high as 10.5 m/s were needed to simulate the highest energy impacts recorded in vivo. The knowledge gained from this study may provide the basis for improving sports headgear test apparatuses with regard to mimicking in vivo linear head accelerations. Specifically, increasing the stiffness of the neck is recommended. In addition, this study may provide a basis for selecting appropriate test impact energies for the standard performance specification to accompany the proposed standard linear impactor test method.
Evolution and the second law of thermodynamics
Authors: Bunn Emory F.
Published: September 2009

Skeptics of biological evolution often claim that evolution requires a decrease in entropy, giving rise to a conflict with the second law of thermodynamics. This argument is fallacious because it neglects the large increase in entropy provided by sunlight striking the Earth. A recent article provided a quantitative assessment of the entropies involved and showed explicitly that there is no conflict. That article rests on an unjustified assumption about the amount of entropy reduction involved in evolution. I present a refinement of the argument that does not rely on this assumption.
A pedagogical discussion of the gravitational energy radiated by Keplerian systems
Authors: Bracco Christian , Provost Jean-Pierre , Salati Pierre
Published: September 2009

We discuss the use of dimensional analysis and the quadrupolar emission hypothesis to determine the gravitational power radiated by a celestial body in a circular orbit. We then show how to derive the instantaneous power radiated in a general Keplerian orbit by approximating it locally by a circle. This derivation allows us to recover with good accuracy the nontrivial dependence given by general relativity relating the average radiated power to the eccentricity of an ellipse. The approach is understandable by undergraduate students.
A one-way speed of light experiment
Authors: Greaves E. D. , Rodríguez An Michel , Ruiz-Camacho J.
Published: September 2009

A recently proposed experiment that demonstrates the feasibility of carrying out a one-way measurement of the speed of light was performed using a time of flight technique. A single oscillator amplitude modulates a He–Ne laser beam, which transverses a distance to a sensor. The output signal returns via a coaxial cable to a digital oscilloscope where the phase difference between the reference and the sensor signals is measured as a function of the distance traveled by the light. The results, within 0.4% of the accepted value of c, prove the feasibility of measuring the speed of light moving in one direction.
Rotating crystal microwave Bragg diffraction apparatus
Authors: Amato Joseph C. , Williams Roger E.
Published: September 2009

An easily constructed microwave Bragg diffraction apparatus is described, suitable for students in introductory physics classes. In contrast with previously published designs, only a single device, either the transmitter or the receiver, must be rotated in order to locate and unambiguously identify Bragg scattering maxima from several low-index (hkl) crystal planes. Employing the “rotating crystal” technique, the orientation of the crystal need not be known a priori. This allows the students to use their measurements of θBragg to determine the lattice spacing and the orientation of a concealed crystal, thereby mimicking the procedures used in real x-ray crystallography.
History of physics: Outing the hidden curriculum?
Authors: Kortemeyer Gerd , Westfall Catherine
Published: September 2009

We describe a history of physics course, cotaught by a physicist and a historian of physics, on the quantum and relativity revolutions in the early part of the 20th century. The course has been taught both in Europe as part of a study abroad program and as a regular on-campus course, which could serve as a model for implementation elsewhere. We present some evidence that this course format can favorably influence students’ epistemological beliefs and expectations about physics.
A research-based interactive lecture demonstration on sinking and floating
Authors: Loverude M. E.
Published: September 2009

Many students have incorrect ideas about sinking and floating. Traditional instruction typically fails to address these ideas. Prior research-based interventions have required much time and/or good understanding of prerequisite concepts. This article describes an interactive lecture activity on buoyancy that has proven successful at addressing common conceptual difficulties with a smaller investment of time.
Contactless measurement of resistivity with DATASTUDIO
Authors: Kraftmakher Yaakov
Published: September 2009

Contactless measurements of the resistivity of nonmagnetic metals are performed automatically with a data-acquisition system. The numerical value of the resistivity appears immediately at the end of data collection. The experiment can be used for student projects.
Attitudes and Action: Public Opinion and the Occurrence of International Terrorism
Authors: Krueger Alan B. , Malečková Jitka
Published: September 2009

Predicting Terrorism?

Terrorists may be extremists whose opinions do not reflect the mainstream views in their country. Alternatively, public opinion could provide a useful indicator of the likelihood of terrorism.
Krueger and Malečková
(p.
1534
) used data from the Gallup World Poll of public opinion and the National Counter Terrorism Center to demonstrate a positive relationship between the percentage of people in a country who disapprove of the leadership of another country and the number of terrorist attacks carried out by people or groups from the former country against the latter. Although the data do not demonstrate causality, they do suggest that public opinion can provide an “early warning signal” of future terrorist threats.
A Constant Flux of Diverse Thermophilic Bacteria into the Cold Arctic Seabed
Authors: Hubert Casey , Loy Alexander , Nickel Maren , Arnosti Carol , Baranyi Christian , Brüchert Volker , Ferdelman Timothy , Finster Kai , Christensen Flemming Mønsted , Rosa de Rezende Júlia , Vandieken Verona , Jørgensen Bo Barker
Published: September 2009

Monitoring Massive Microbial Dispersal

Quantifying the relative influence of present-day environmental conditions and geological history on the spatial distribution of species represents a major challenge in microbial ecology. Ecological approaches to distinguish between these two biogeographic controls are limited by environmental variability both in space and through time (see the Perspective by

Patterson

). Using a 1.5-million-year fossil record of marine diatoms,
Cermeño and Falkowski
(p.
1539
) show that, even at the largest (global) spatial scale, the dispersal of marine diatoms is not very limited. Environmental factors are the primary control shaping the global biogeography of marine diatom morphospecies. Thermophilic microorganisms are routinely detected in permanently cold environments from deep sea sediments to polar soils.

Hubert
et al.

(p.
1541
) provide a quantitative analysis of a potentially large-scale dispersion of thermophilic bacteria in the ocean. Approximately 10
8
thermophilic spores are deposited each year on every square meter of Arctic sediment.
Controls on Diatom Biogeography in the Ocean
Authors: Cermeño Pedro , Falkowski Paul G.
Published: September 2009

Monitoring Massive Microbial Dispersal

Quantifying the relative influence of present-day environmental conditions and geological history on the spatial distribution of species represents a major challenge in microbial ecology. Ecological approaches to distinguish between these two biogeographic controls are limited by environmental variability both in space and through time (see the Perspective by

Patterson

). Using a 1.5-million-year fossil record of marine diatoms,
Cermeño and Falkowski
(p.
1539
) show that, even at the largest (global) spatial scale, the dispersal of marine diatoms is not very limited. Environmental factors are the primary control shaping the global biogeography of marine diatom morphospecies. Thermophilic microorganisms are routinely detected in permanently cold environments from deep sea sediments to polar soils.

Hubert
et al.

(p.
1541
) provide a quantitative analysis of a potentially large-scale dispersion of thermophilic bacteria in the ocean. Approximately 10
8
thermophilic spores are deposited each year on every square meter of Arctic sediment.
Three-Dimensional Structural View of the Central Metabolic Network of
Thermotoga maritima
Authors: Zhang Ying , Thiele Ines , Weekes Dana , Li Zhanwen , Jaroszewski Lukasz , Ginalski Krzysztof , Deacon Ashley M. , Wooley John , Lesley Scott A. , Wilson Ian A. , Palsson Bernhard , Osterman Andrei , Godzik Adam
Published: September 2009

Now Shown in 3D

With the advent of systems-wide technologies and the development of analytical methods, data produced by analyzing individual or small groups of molecular components can be integrated to reassemble whole biological systems.

Zhang
et al.

(p.
1544
) have undertaken a major technological challenge: to integrate biochemical data with experimentally determined or predicted three-dimensional structures of all proteins involved in the central metabolism of a bacterial cell. This integration of large-scale data sets provides evolutionary and functional insights and furthers our understanding of the molecular assembly of complex biological networks.
Comment on “The Dynamic Control of Kiss-and-Run and Vesicular Reuse Probed with Single Nanoparticles”
Authors: Granseth Björn , Odermatt Benjamin , Royle Stephen J. , Lagnado Leon
Published: September 2009

Zhang
et al
. (Research Articles, 13 March 2009, p. 1448) reported that synaptic vesicles usually release neurotransmitter through a kiss-and-run mechanism occurring within 1 second but that full collapse of the vesicles becomes more prevalent with repeated stimuli. We report that the kinetics of vesicle retrieval do not change during a stimulus train, with endocytosis occurring in 10 to 15 seconds.
Details of Insect Wing Design and Deformation Enhance Aerodynamic Function and Flight Efficiency
Authors: Young John , Walker Simon M. , Bomphrey Richard J. , Taylor Graham K. , Thomas Adrian L. R.
Published: September 2009

Locust Wing Aerodynamics

Insect wings function as deformable aerofoils, but the precise aerodynamic benefits of the observed deformations have remained obscure. Previous models have treated the wing as a flat plate, lacking any deformation, even though it is clear that the locust wing can twist and rotate along its length.

Young
et al.

(p.
1549
) validate a computational fluid dynamic model, using particle imaging velocimetry and smoke visualization of the flow around actual locusts, and use the model to investigate the effect of measured changes in wing shape during a stroke cycle. The complexity of insect wing venation directly affects the aerodynamics of flight via the intermediary of wing deformation.
Response to Comment on “The Dynamic Control of Kiss-And-Run and Vesicular Reuse Probed with Single Nanoparticles”
Authors: Zhang Qi , Li Yulong , Tsien Richard W.
Published: September 2009

Granseth
et al
. argue that vesicle retrieval at hippocampal synapses is fully accounted for by a single mode of endocytosis. However, their assay focused on readily releasable pool vesicles (RRP), not RRP + reserve pool vesicles in tandem, and therefore cannot detect pool-dependent changes in vesicle-retrieval kinetics during a stimulus train. Using a probe similar to theirs, we observed rapid vesicle retrieval consistent with Kiss-And-Run fusion.
Highly Variable Spread Rates in Replicated Biological Invasions: Fundamental Limits to Predictability
Authors: Melbourne Brett A. , Hastings Alan
Published: September 2009

Limits to Invasion Predictions

Using mathematical models linked to experiments on laboratory insect populations,
Melbourne and Hastings
(p.
1536
) show that current models seriously underestimate variability in spatial spread. Genetic founder effects resulting from small population sizes are probably responsible for the surprising increase in variability and for increased uncertainty of ecological forecasts. Thus, even without exogenous sources of variability such as weather, fundamental uncertainties arise biologically from inherent differences among individuals and small population sizes.
Control of Iron Homeostasis by an Iron-Regulated Ubiquitin Ligase
Authors: Vashisht Ajay A. , Zumbrennen Kimberly B. , Huang Xinhua , Powers David N. , Durazo Armando , Sun Dahui , Bhaskaran Nimesh , Persson Anja , Uhlen Mathias , Sangfelt Olle , Spruck Charles , Leibold Elizabeth A. , Wohlschlegel James A.
Published: September 2009

Iron Sensor

Intracellular iron is an essential cofactor for many proteins, but can also damage macromolecules, so its levels are carefully controlled. Cellular iron homeostasis is mediated by iron regulatory proteins that regulate the expression of genes involved in iron uptake and storage. However, it is not clear how cells sense iron bioavailability (see the Perspective by

Rouault

). Using different approaches,

Salahudeen
et al.

(p.
722
, published online 17 September) and

Vashisht
et al.

(p.
718
, published online 17 September) have identified the F-box protein FBXL5 as a human iron sensor. FBXL5 is part of an E3 ubiquitin ligase complex that regulates the degradation of iron regulatory proteins and thereby cellular iron levels. It contains a hemerythrin domain that binds iron and acts as an iron-dependent regulatory switch, causing the degradation of FBXL5 under low iron conditions. This alternative pathway for the regulation of iron homeostasis has implications for both normal cellular physiology and disease.
The Super of Superradiance
Authors: Scully Marlan O. , Svidzinsky Anatoly A.
Published: September 2009

Cooperative single-photon emission from an atom ensemble will provide insights into quantum electrodynamics and applications in quantum communication.
Ecology Emerging
Modern Nature
The Rise of the Biological Perspective in Germany

by Lynn K. Nyhart

University of Chicago Press, Chicago, 2009. 437 pp. $45, £31. ISBN 9780226610894.
Authors: Glaubrecht Matthias
Published: September 2009

Exploring the work in museums, zoos, botanic gardens, and secondary schools in late-19th-century Germany, Nyhart shows that the popular nature studies played a crucial role in the development of ecology.
Tyrannosaurid Skeletal Design First Evolved at Small Body Size
Authors: Sereno Paul C. , Tan Lin , Brusatte Stephen L. , Kriegstein Henry J. , Zhao Xijin , Cloward Karen
Published: September 2009

Diddy Dinosaurs

Tyrannosaurs were the dominant large dinosaur predator during the Late Cretaceous. They have several distinct specialized features, including an oversized skull, huge hindlimbs, and tiny arms, that have been thought to have evolved in concert with their large size and carnivorous diet.

Sereno
et al.

(p.
418
, published online 17 September; see the Perspective by

Clark

) now describe an earlier, diminutive tyrannosaur from China that also has these common specializations. Thus, these features were not a result of size increase but appear to have been required for feeding efficiency at all sizes.
Many Reflections on Birds
Birdscapes
Birds in Our Imagination and Experience

by Jeremy Mynott

Princeton University Press, Princeton, NJ, 2009. 389 pp. $29.95, £17.95. ISBN 9780691135397.
Authors: Bennu Devorah
Published: September 2009

Mynott offers an eclectic philosophical exploration of our multifaceted experience with birds.
D-Amino Acids Govern Stationary Phase Cell Wall Remodeling in Bacteria
Authors: Lam Hubert , Oh Dong-Chan , Cava Felipe , Takacs Constantin N. , Clardy Jon , de Pedro Miguel A. , Waldor Matthew K.
Published: September 2009

Anyone for
d
?

The chemistry of amino acids comes in two chirally distinct flavors—so-called
l
- and
d
-enantiomers. By far the most commonly used form of amino acids in all kingdoms of life is the
l
-form. Now

Lam
et al.

(p.
1552
; see the Perspective by

Blanke

) present the unanticipated observation that diverse bacteria release large amounts of various
d
-amino acids into the environment in a population density–dependent fashion and that
d
-amino acids act as extracellular effectors that regulate the composition, structure, amount, and strength of peptidoglycan, the major stress-bearing component of the bacterial cell wall.
How River Beds Move
Authors: Frey Philippe , Church Michael
Published: September 2009

Insights into sediment transport at river beds can come from experiments in granular physics.
Laskers Honor Five Scientists and a Mayor
Authors: Torrice Michael
Published: September 2009

Five biomedical researchers and the billionaire mayor of New York City have been selected for the 2009 Lasker Awards.
Researcher, Two Universities Sued Over Validity of Prostate Cancer Test
Authors: Kaiser Jocelyn
Published: September 2009

A Johns Hopkins University researcher whose reports of a potential new blood test for diagnosing prostate cancer generated excitement—but also skepticism—is now being sued by his industry sponsor for scientific fraud.
DuPont Scientist Accused of Stealing Company's Trade Secrets
Authors: Service Robert F.
Published: September 2009

A Chinese-born scientist, one of the leading researchers in the field of next-generation display technologies, has been fired by DuPont, which alleges he attempted to steal company secrets.
PNAS
Nixes Special Privileges for (Most) Papers
Authors: Kean Sam
Published: September 2009

The
Proceedings of the National Academy of Sciences
will discontinue an option for submitting papers that often put prestigious scientists in an awkward fix with colleagues and, at its worst, editors admit, allowed some scientists to subvert peer review and shoehorn dubious papers into print.
A Boost for Vaccine Development
Authors: Travis John
Published: September 2009

This week, Merck and the U.K. biomedical charity Wellcome Trust established a nonprofit vaccine development institute to be based in India.
A Cure for Euthanasia?
Authors: Grimm David
Published: September 2009

A nonsurgical sterilant could reduce the global population of homeless dogs and cats, but there hasn't been money to develop one—until now.
Activity of the Novel Peptide Arminin against Multiresistant Human Pathogens Shows the Considerable Potential of Phylogenetically Ancient Organisms as Drug Sources
Authors: Augustin René , Anton-Erxleben Friederike , Jungnickel Stephanie , Hemmrich Georg , Spudy Björn , Podschun Rainer , Bosch Thomas C. G.
Published: September 2009

The emergence of multidrug-resistant bacteria highlights the need for new antibacterial agents. Arminin 1a is a novel antimicrobial peptide discovered during investigations of the epithelial defense of the ancient metazoan
Hydra
. Following proteolytic processing, the 31-amino-acid-long positively charged C-terminal part of arminin 1a exhibits potent and broad-spectrum activity against bacteria, including multiresistant human pathogenic strains, such as methicillin-resistant
Staphylococcus aureus
(MRSA) strains (minimal bactericidal concentration, 0.4 μM to 0.8 μM). Ultrastructural observations indicate that bacteria are killed by disruption of the bacterial cell wall. Remarkably, the antibacterial activity of arminin 1a is not affected under the physiological salt conditions of human blood. In addition, arminin 1a is a selective antibacterial agent that does not affect human erythrocyte membranes. Arminin 1a shows no sequence homology to any known antimicrobial peptide. Because of its high level of activity against multiresistant bacterial strains pathogenic for humans, the peptide arminin 1a is a promising template for a new class of antibiotics. Our data suggest that ancient metazoan organisms such as
Hydra
hold promise for the detection of novel antimicrobial molecules and the treatment of infections caused by multiresistant bacteria.
Unusual reaction of 2-(aminomethyl)benzimidazole with chalcones: Synthesis of new aryl-substituted pyrrolines
Authors: Borovskoy Valery A. , Komykhov Sergey A. , Musatov Vladimir I. , Shishkina Svetlana V. , Shishkin Oleg V. , Desenko Sergey M.
Published: September 2009

The reaction of 2-(aminomethyl)benzimidazole (1) with chalcones 2a–2e leads to formation of 3,5-diaryl-2-benzimidazol-2-yl-4,5-dihydropyrroles 3a–3e. The trans orientation of benzimidazol-2-yl and 3-aryl substituents in 3a–3e was established by X-ray analysis of 3e.
NICE and neurology
Authors: Chadwick David
Published: September 2009

The National Institute for Health and Clinical Excellence (NICE) is 10 years old and has now issued a number of technology appraisals for new treatments for neurological disorders. Those for multiple sclerosis and dementia have been controversial and have attracted particular media attention, to say nothing of strong feelings within British neurology. Some of its other activities, which include both appraisals of interventions and clinical guidelines, have attracted less notice but form an important part of its remit. There is no doubt that NICE has had an impact on neurological care in the UK which for the most part has been beneficial. It has a vital role in managing the relationship between the NHS and pharma, and helps ensure equity in access to new and potentially expensive treatments.
Treating women with juvenile myoclonic epilepsy
Authors: Craig John J , Hunt Stephen J
Published: September 2009

Epilepsy has special implications for women, especially during their childbearing years, and particularly when pregnancy is contemplated. Being aware of the relevant issues is therefore essential. For anyone with juvenile myoclonic epilepsy and other idiopathic generalised epilepsies, valproate is generally regarded as the gold standard treatment against which other antiepileptic drugs are compared. However, information from pregnancy registers consistently show valproate to be associated with the highest risk for major congenital malformations, and studies exploring cognitive and behavioural development of offspring also show that valproate has an adverse impact. This creates a significant headache when trying to choose the “right” drug for most women with a generalised epilepsy syndrome.
Distribution and Abundance of Haddock (Melanogrammus aeglefinus) and Atlantic Cod (Gadus morhua) Eggs and Larvae in the Waters off Southwest Nova Scotia
Authors: Hurley Peter C. F. , Campana Steven E.
Published: September 2009

Synoptic ichthyoplankton surveys conducted at monthly intervals during the winter–spring of 1983–85 were used to determine the location, timing, and magnitude of spawning by haddock (Melanogrammus aeglefinus) and Atlantic cod (Gadus morhua) off southwest Nova Scotia. There was a marked similarity in the spawning locations of the two species: primary spawning occurred on Browns Bank, although lower levels of spawning were observed on adjacent banks and in the inshore region. Cod egg abundance peaked in April in all years, while that of haddock varied between April–June.
Intermolt Insemination, an Alternative Mating Strategy for the American Lobster (Homarus americanus)
Authors: Waddy S. L. , Aiken D. E.
Published: September 2009

American lobster (Homarus americanus) have a dual mating strategy. Although most females mate when they are newly molted, mating can occur at any molt stage if necessary, in the laboratory, virtually all uninseminated preovigerous females mate prior to spawning. Male aggression is a major factor in the success of intermolt mating and males can discriminate between immature and mature females, and between inseminated and uninseminated females. Female receptivity is affected by both ovarian stage and the presence of stored sperm, but not by molt stage. Most females become unreceptive after insemination, but their receptivity returns once the supply of stored sperm is exhausted. Intermolt mating occurs in smaller lobster that for some reason did not mate at molt, and it is an important part of the reproductive strategy of larger lobster. Lobster s[Formula: see text] carapace length frequently spawn twice without molting and often fail to store sufficient sperm to fertilize consecutive spawnings. Intermolt mating ensures these females will produce fertile second broods.
Demographic Consequences of Age-Specific Dispersal in Marine Fish Populations
Authors: Frank Kenneth T.
Published: September 2009

The fundamental model of marine fish population dynamics assumes that major events occur within the census area and that immigrants and emigrants can be safely ignored in the evaluation of stock dynamics. Dispersal is generally assumed to be associated with the movement of immature individuals away from their home area. Such a process may produce vagrants that have a low probability of surviving or successfully reproducing elsewhere. An alternative view, developed here, proposes that dispersal can have profound demographic consequences not only for the resident stock but for neighbouring stocks. A review of the fisheries literature and an analysis of data for two Scotian Shelf haddock stocks provided support for the hypothesis that the spatial magnitude of postlarval dispersal is generally density dependent, that vagrants flourish as juveniles outside the home area in neighbouring stocks, that they subsequently return home when mature, and that the recruitment dynamics of the neighbouring stocks are seriously misinterpreted when such movements are ignored. Additional implications of these findings, including synchronous recruitment patterns commonly observed between stocks, density-dependent growth, and groundfish stock management practices, are discussed.
Feeding and Trophic Interactions of White Perch (Morone americana) in the Bay of Quinte, Lake Ontario
Authors: Hurley D. A.
Published: September 2009

White perch (Morone americana) biomass declined dramatically in the Bay of Quinte in 1978 after two abnormally cold winters in 1976–77 and 1977–78. White perch diet was qualitatively and quantitatively different before and after the population decline. Changes in production and standing stocks of diet items were related to reduced eutrophy when phosphorus inputs to the bay were restricted in early 1978. The hypothesis that phytoplankton biomass in the shallow, highly eutrophic upper bay was related to white perch biomass through the benthic food web was not supported by the calculated daily consumption of benthos. White perch consumed about 5% of the daily production of chironomids in 1972–77 and less than 1% in 1978–88. In the less eutrophic, deep lower bay, predation on the amphipod Pontoporeia hoyi in August–September was 112% of daily production before 1978 and affected their biomass. After 1978 when white perch biomass was reduced in the lower bay, daily consumption of P. hoyi was 1% of daily production, and numbers of P. hoyi expanded greatly. Data linking consumption rate of specific diet items to production are necessary to establish trophic relationships and follow the effects of biomass shifts.
Comparison of Chlorophyll a Extractions with Ethanol and Dimethyl Sulfoxide/Acetone, and a Concern about Spectrophotometric Phaeopigment Correction
Authors: Webb D. J. , Burnison B. K. , Trimbee A. M. , Prepas E. E.
Published: September 2009

Chlorophyll a (Chl a) in water samples from three mesotrophic to eutrophic lakes in north-central Alberta was extracted with one of three solvents (95% ethanol, 90% ethanol, or a 2:3 mixture of dimethyl sulfoxide and 90% acetone (DMSO/acetone)) and analyzed by two techniques (spectrophotometry and high pressure liquid chromatography (HPLC). The dominant phytoplankton were blue-green algae and diatoms. Total Chl a concentrations (i.e. no correction for phaeopigments (Pha)) were not significantly different among solvents (P > 0.5). Total Chl a concentrations from spectrophotometric analyses were significantly higher than those from HPLC analyses (4.2 ± 0.88 and 2.6 ± 0.50 μg∙L−1 respectively, P < 0.05). Pha concentrations derived by spectrophotometry were 64 times higher than those derived by HPLC (1.7 ± 0.52 and 0.025 ± 0.01 μg∙L−1 respectively, P < 0.005). Thus, spectrophotometry appears to dramatically overestimate Pha concentrations and may overestimate total Chl a (i.e. no correction for Pha). Therefore, ethanol and DMSO/acetone are equally suitable for Chl a extraction from natural populations dominated by blue-green algae and/or diatoms, but if information on Pha and/or accessory pigments is required, HPLC analyses are the appropriate route rather than spectrophotometry.
Salmonid Phylogeny Inferred from Ribosomal DNA Restriction Maps
Authors: Phillips Ruth B. , Pleyte Kay A. , Brown Michael R.
Published: September 2009

Genomic DNA was isolated from 17 salmonid species including six species of Salvelinus (S. namaycush, S. fontinalis, S. leucomaenis, S. confluentus, S. malma, and S. alpinus), two species of Salmo(S. trutta and S. salar), eight species of Oncorhynchus (O. mykiss, O. clarki, O. masou, O. tshawytscha, O. kisutch, O. keta, O. nerka, and O. gorbuscha), and one species of Hucho (H. perryi). Restriction maps of the ribosomal DNA were prepared by using probes to the 18S and 28S coding regions of the rDNA. Phylogenies were constructed from this data using both cladistic and distance methods. Results supported the recent placement of the Pacific trouts in the genus Oncorhynchus. The phylogeny obtained for the genus Salvelinus suggested that S. confluentus from North America may be more closely related to S. leucomaenis from Japan than to species in the S. malma – S. alpinus complex. Fixed differences in restriction sites were found among the major subgroups within the S. malma – S. alpinus complex.