bluuebunny/crossref_metadata_2025 huggingface dataset:
River dredging, channel dynamics and bedload transport in an incised meandering river (the River Semois, Belgium)
Authors: Gob F. , Houbrechts G. , Hiver J. M. , Petit F.
Published: September 2005

Dredging in the rivers of the Ardenne is generally carried out on a smaller scale to that described in the literature and is not conducted for commercial purposes. Extractions within the river channel are made in order to prevent flooding; hence the quantity of gravel extracted is limited. This study aims to evaluate the impact of dredging and the resilience of the riverbed in the Semois. This river is found in the south of the Ardenne region and is characterized by large incised meanders, a narrow floodplain, few pebble bars, numerous bedrock outcrops and a limited stock of sediment. The bed is particularly flat and shallow and the bankfull discharge (130 m3 s−1) is frequently attained (0.9 yr). Pebble tracers allowed the critical parameters (discharge, Shields criterion, and stream power), the diameter of mobilized sediment and the distance of sediment transport to be determined. A major dredging campaign resulted in the formation of a channel nearly 1 km long and 2 m deep which functioned as a sediment trap. Topographical cross‐sections made before and after the dredging campaign and again 4 yr later allowed bedload discharge to be estimated (1.1 t km−1 yr−1). In order to examine the efficiency of the sediment trap, the sediment transport equations of Meyer‐Peter and Müller, Schoklitsch, Bagnold and Martin were applied. With the exception of Bagnold's equation (1980), the observed transport values and those calculated theoretically are relatively close. Between October 1997 and June 2001, 5010 t were caught in the sediment trap. For the same period the equations calculate values between 6147 and 10 571 t. The overestimation from the theoretical calculations may result from a lack of sediment supply due to the characteristics of the basin and the frequency and magnitude of flood events during the study period. From the magnitude of the sediment transport rate, a return to the initial state of the riverbed (before dredging) may be expected after approximately 10 yr. Despite the scale of the dredging campaign for a river of this size, its results are limited in terms of flood prevention. Copyright © 2005 John Wiley & Sons, Ltd.
Sediment mining in alluvial channels: physical effects and management perspectives
Authors: Rinaldi M. , Wyżga B. , Surian N.
Published: September 2005

Based on a review of a number of documented case studies from various countries and a detailed analysis of sediment exploitation from five rivers in Italy and Poland, we discuss alluvial river response to extensive sediment mining. A sediment deficit caused by in‐stream mining typically induces upstream‐ and downstream‐progressing river incision, lateral channel instability and bed armouring. The resultant incision alters the frequency of floodplain inundation along the river courses, lowers valley‐floor water tables and frequently leads to destruction of bridges and channelization structures. Mining also results in the loss or impoverishment of aquatic and riparian habitats. In the rivers of Italy and southern Poland studied, where mining coincided with other human activities that reduce sediment delivery to the channels, deep river downcutting, changes in channel pattern and, in one case, transformation from alluvial to bedrock boundary conditions were recorded over recent decades.

The type and magnitude of channel response to sediment mining depend mainly on the ratio between extraction and sediment replenishment rates. The effects of mining will be especially severe and difficult to reverse: (i) where material is extracted at a rate greatly exceeding the replenishment rate; (ii) in single‐thread rivers, that are generally associated with relatively low rates of catchment sediment supply; (iii) in channelized reaches; (iv) where rivers are underlain by a thin cover of alluvium over bedrock; and (v) where mining coincides with other human activities that reduce upstream sediment delivery. With a large number of detrimental effects of instream mining, the practice should be prohibited in most rivers except aggrading ones. Copyright © 2005 John Wiley & Sons, Ltd.
Influence of wind turbine flexibility on loads and power production
Authors: Ahlström Anders
Published: September 2005

Most aeroelastic codes used today assume small blade deflections and application of loads on the undeflected structure. However, with the design of lighter and more flexible wind turbines, this assumption is not obvious. By scaling the system mass and stiffness properties equally, it is possible to compare wind turbines of different degrees of slenderness and at the same time keep system frequencies the same in an undeformed state. The developed model uses the commercial finite element system MSC. Marc, focused on non‐linear design and analysis, to predict the structural response. The aerodynamic model AERFORCE, used to transform the wind to loads on the blades, is a blade element momentum model. A comparison is made between different slenderness ratios in three wind conditions below rated wind speed. The results show that large blade deflections have a major influence on power production and the resulting structural loads and must be considered in the design of very slender turbines. Copyright © 2005 John Wiley & Sons, Ltd.
Bathymetric shift in the distribution of Atlantic surfclams: response to warmer ocean temperature
Authors: Weinberg James R.
Published: September 2005

Standard research vessel surveys during the 1980s and early 1990s demonstrated that Atlantic surfclams (Spisula solidissima solidissima) were common in the southern portion of their range (37–38°N) along the east coast of North America in the Delmarva region. Based on data from these surveys, the probability of capturing surfclams in shallow water (i.e. 20 m) tows of the Delmarva region was 75–85% in 1994 and 1997. In 1999 and 2002, this probability declined to 40–55%. The probability of capturing surfclams in survey tows from deeper waters (40–50 m) also declined, but this change was relatively small compared with that in shallower water. These changes were not the result of commercial clam fishing. Unusually warm water, which induces thermal stress in S. s. solidissima, was prevalent within the period from 1999 to 2002 over the Delmarva continental shelf during fall when annual bottom temperature was peaking. The combined effects of poor physiological condition and thermal stress likely resulted in mortality of Atlantic surfclams in shallow water habitats in the Delmarva region. This resulted in a shift in the bathymetric distribution of the population to deeper water. Between 1982 and 1997, most of the surfclams in the Delmarva region occurred at depths between 25 and 35 m, whereas in 1999 and 2002, most of the Delmarva population occurred at 35–40 m.
Lipid metabolism during lactation: a review of adipose tissue-liver interactions and the development of fatty liver
Authors: Vernon Richard G
Published: September 2005

Fatty acids are the major source of energy for most tissues during periods of negative energy balance; however, fatty acids can, in some circumstances, have pathological effects. Fatty acids are stored as triacylglycerols (TAG), mostly in the various adipose tissue depots of the body. However, if blood unesterified fatty acid (NEFA) levels are elevated for prolonged periods, as may occur during lactation or obesity, TAG can accumulate in other tissues including liver and muscle cells (myocytes), and this can have pathological consequences such as the development of ketosis (Grummer, 1993; Drackley et al. 2001) or type 2 diabetes (Boden & Shulman, 2002; McGarry, 2002).
Distribution of leucocyte populations, and milk composition, in milk fractions of healthy quarters in dairy cows
Authors: Sarikaya Hande , Werner-Misof Claudia , Atzkern Melanie , Bruckmaier Rupert M
Published: September 2005

The goal of the study was to evaluate the composition of leucocyte populations in different milk fractions as a basis on which to judge their possible role in the immune response in different compartments of the udder. The milk of one healthy quarter of nine dairy cows (SCC/quarter [les ]125000/ml; bacteriologically negative) was removed separately and during the course of milking divided into: cisternal milk (C), alveolar milk 0–25%, 25–50%, 50–75%, 75–100% (A25; A50; A75; A100, respectively) and residual milk (R). Each fraction was analysed for the main constituents, SCC and distribution of leucocyte populations and their viability. The content of fat increased steadily during milking and reached highest values in R. Protein and lactose increased from C to A25, decreased from A25 to A100 and reached their minimum in R. Na and Cl ion levels diminished from C to A25 and thereafter increased from A50 to R. Electrical Conductivity (EC) also decreased from C to A25 but remained similar within the alveolar samples and reached a minimum in R. SCC decreased from C to a minimum in A25 and increased subsequently to a significant maximum in R. Somatic cell viability increased throughout consecutive fractions with a maximum value in R. The ratio of cell populations in the various milk fractions showed a reverse trend of macrophages (M) and polymorphonuclear neutrophils (PMN). M values were highest in C while PMN levels increased to their maximum in the R fraction. The lymphocyte (L) fraction remained similar in C, A25, A50, A75 and R but was higher in A100. Proportions of L, PMN and M were, respectively, 9·3%, 38·2%, 52·3% in C, 10·9%, 64%, 25·1% in A25–A100 and 10·2%, 64·9%, 24·8% in R. Numbers of L, PMN and M in milk showed a similar pattern for all three cell types: high levels in C decreased to a minimum at A25 and increased steadily thereafter to their maxima in R. It is concluded that, for healthy quarters, M, the predominant cell type in C, are located near the teat canal, the main entrance of pathogens. Obviously they are the first immunological barriers for invading pathogens. In contrast, PMN are the most important population in the alveolar compartment. However, each leucocyte fraction had a higher concentration in C than in early alveolar fractions, thus indicating the crucial role of immune defence in the cisternal compartment.
Oxytocin release and lactation performance in Syrian Shami cattle milked with and without suckling
Authors: Kaskous Shehadeh H , Weiss Daniel , Massri Yassin , Al-Daker Al-Moutassem B , Nouh Ab-Dallah , Bruckmaier Rupert M
Published: September 2005

Oxytocin (OT) release and lactation performance in primiparous Syrian Shami cows were evaluated in response to two different machine milking regimes. Six cows were milked in the presence of the calves (PC) and subsequently suckled, whereas six cows were exclusively machine milked without the presence of their calves (WC) until day 91 post partum. Milk yield and milk constituents were determined weekly. The degree of udder evacuation was determined by the succeeding removal of residual milk. PC released OT during the milking process, whereas in WC no OT release was detected throughout the milking process. Consequently, the residual milk fraction was much lower in PC than in WC (11% v. 58%, P<0·05) and daily milk yield until day 91 post partum was higher in PC than in WC (12·6±0·3 v. 7·1±0·4 kg, P<0·05). In conclusion, Syrian Shami cattle are not suitable to be exclusively machine milked without the presence of their calves.
Behavior of γ-tubulin during spindle formation in Xenopus oocytes: requirement of cytoplasmic dynein-dependent translocation
Authors: Kotani Tomoya , Yamashita Masakane
Published: September 2005

Vertebrate oocytes do not contain centrosomes and therefore form an acentrosomal spindle during oocyte maturation. γ-Tubulin is known to be essential for nucleation of microtubules at centrosomes, but little is known about the behaviour and role of γ-tubulin during spindle formation in oocytes. We first observed sequential localization of γ-tubulin during spindle formation in Xenopus oocytes. γ-Tubulin assembled in the basal regions of the germinal vesicle (GV) at the onset of germinal vesicle breakdown (GVBD) and remained on the microtubule-organizing centre (MTOC) until a complex of the MTOC and transient-microtubule array (TMA) reached the oocyte surface. Prior to bipolar spindle formation, oocytes formed an aggregation of microtubules and γ-tubulin was concentrated at the centre of the aggregation. At the late stage of bipolar spindle formation, γ-tubulin accumulated at each pole. Anti-dynein antibody disrupted the localization of γ-tubulin, indicating that the translocation described above is dependent on dynein activity. We finally revealed that XMAP215, a microtubule-associated protein cooperating with γ-tubulin for the assembly of microtubules, but not γ-tubulin, was phosphorylated during oocyte maturation. These results suggest that γ-tubulin is translocated by dynein to regulate microtubule organization leading to spindle formation and that modification of the molecules that cooperate with γ-tubulin, but not γ-tubulin itself, is important for microtubule reorganization.
Ultrastructural study of spermatozoa of the paddlefish, Polyodon spathula
Authors: Zarnescu Otilia
Published: September 2005

Paddlefish, Polyodon spathula, spermatozoa were examined by transmission electron microscopy. Their structure has the same characteristic architectural features as sturgeon spermatozoa. Paddlefish spermatozoa are of the primitive type and consist of a rod-shaped head, a midpiece and a long flagellum. The head is about 5.15 mm in length and contains the nucleus and an apical acrosomal complex. Inside the nucleus there are three nuclear channels that begin in the subacrosomal area and have a triple helical arrangement. An nuclear fossa is present centrally, at the posterior end of the nucleus. The midpiece contains a pair of centrioles in a perpendicular arrangement, mitochondria and a narrow cytoplasmic sleeve. The flagellum has a central axoneme with a 9+2 pattern and two lateral projections or fins.
Extensive observations of CO2 carbon isotope content in and above a high‐elevation subalpine forest
Authors: Bowling D. R. , Burns S. P. , Conway T. J. , Monson R. K. , White J. W. C.
Published: September 2005

The dynamics of forest‐atmosphere CO2 carbon isotope exchange were examined in a coniferous forest in Colorado, United States. Tunable diode laser absorption spectrometry provided extensive characterization of the carbon isotope content (δ13C) of CO2. Observed patterns in δ13C of forest air were associated with photosynthesis, respiration, and atmospheric boundary layer dynamics. Similar relationships between δ13C and CO2 were observed at all forest heights and confined to a relatively narrow envelope. Substantial variation was observed in the isotope ratio of nocturnal ecosystem respiration (δ13CR, calculated from isotopic mixing lines). A systematic bias was identified when estimating δ13CR from data sets with small range in CO2 in the samples, leading us to restrict analysis of δ13CR to periods with CO2 range >40 μmol mol−1. Values of δ13CR varied from −28.1 to −25.2‰, with variation from one night to the next as large as 1.7‰. A consistent difference was observed between δ13CR calculated near the forest floor (<2 m height) versus the upper canopy (5–11 m) on the same nights. δ13CR was more enriched in the upper canopy than near the ground on 34 of 43 nights, with a mean enrichment of 0.6‰ and a maximum of 2.3‰. A similar pattern was observed comparing δ13CR at night with the analogous quantity calculated during daytime, but only a few daytime periods met the 40 μmol mol−1 criterion. Comparisons between air samples measured (1) 10 m above the forest canopy, (2) 3 km away, and (3) within the convective boundary layer 125 km distant showed CO2 differences between sites as large as 5–6 μmol mol−1 even at midday. These results suggest that attempts to use flask measurements at remote monitoring stations as a proxy for the air directly interacting with a vegetation canopy should be made with caution. However, our results also suggest that substantial information about biosphere‐atmosphere isotopic exchange can be obtained by simultaneous examination of CO2 and δ13C at multiple spatial scales.
Self‐consistent electron acceleration due to inertial Alfvén wave pulses
Authors: Watt C. E. J. , Rankin R. , Rae I. J. , Wright D. M.
Published: September 2005

We present self‐consistent kinetic simulations of the electron response to finite duration shear Alfvén wave pulses in a magnetized plasma. In Earth's magnetosphere, the evidence suggests that parallel electric fields in inertial scale shear Alfvén waves can accelerate electrons in the geomagnetic field‐aligned direction. Here, we study large‐amplitude wave forms as they travel through ambient plasma at phase velocities which are consistent with resonant electron acceleration predicted by linear kinetic theory. Our self‐consistent simulations reveal that the wave potential evolves nonlinearly as shear Alfvén wave pulses travel through the simulation domain. The evolution of the wave pulse from a symmetrical to a nonsymmetrical potential structure, and the large perturbation in the distribution function required to carry the parallel current of the pulse, leads to nonresonant acceleration of electrons (i.e., acceleration of electrons which are not traveling at the same velocity as the wave). We compare the signature of resonant and nonresonant electron acceleration with data from a low‐altitude spacecraft and suggest an explanation for features often referred to as field‐aligned suprathermal electron bursts. Finally, we discuss how resonant and nonresonant acceleration of electrons is affected by the perpendicular wavelength and amplitude of shear Alfvén wave pulses.
On the correlation between air‐sea heat flux and abiotically induced oxygen gas exchange in a circulation model of the North Atlantic
Authors: Dietze H. , Oschlies A.
Published: September 2005

The assumption that abiotic air‐sea gas exchange is, via the temperature dependence of the gas' solubility, proportional to the surface heat flux is often used to distinguish between physically and biotically inferred oxygen fluxes across the sea surface. We quantitatively investigate its validity in the context of an eddy‐permitting circulation model that contains an abiotic oxygen compartment. In the model, the “true” abiotic oxygen air‐sea fluxes are systematically lower than those predicted by the air‐sea heat flux relation. This discrepancy is caused by the nonlinear relationship between temperature and solubility that results in the saturation of a mixed water parcel being higher than the arithmetic mean saturation of the mixed components. This effect results in a simulated additional sea‐to‐air oxygen flux of about 0.5 mol O2 m−2 a−1 north of 40°N, which is not accounted for by the heat‐flux relation and which is of similar magnitude as, though at the lower end of, biotically induced oxygen fluxes. Simulated outgassing of the model's abiotic oxygen is also higher than that predicted by the heat‐flux relation at the equator (by ≈0.25 mol O2 m−2 a−1), where numerical artifacts endemic to state‐of‐the‐art z level ocean models are found to affect simulated air‐sea gas exchange. In addition to discrepancies in the annual mean fluxes, model results also indicate that the subtropical seasonal cycle in abiotic air‐sea oxygen exchange is smaller by approximately 20% than the estimate based on air‐sea heat fluxes, a result consistent with admittedly sparse observations of argon saturation.
Synergistic effects of temperature extremes, hypoxia, and increases in CO2on marine animals: From Earth history to global change
Authors: Pörtner Hans O. , Langenbuch Martina , Michaelidis Basile
Published: September 2005

Currently rising CO2levels in atmosphere and marine surface waters as well as projected scenarios of CO2disposal in the ocean emphasize that CO2sensitivities need to be investigated in aquatic organisms, especially in animals which may well be the most sensitive. Moreover, to understand causes and effects, we need to identify the physiological processes that are sensitive to CO2beyond the current emphasis on calcification. Few animals may be acutely sensitive to moderate CO2increases, but subtle changes due to long‐term exposure may already have started to be felt in a wide range of species. CO2effects identified in invertebrate fauna from habitats characterized by oscillating CO2levels include depressed metabolic rates and reduced ion exchange and protein synthesis rates. These result in shifts in metabolic equilibria and slowed growth. Long‐term moderate hypercapnia has been observed to produce enhanced mortality with as yet unidentified cause and effect relationships. During future climate change, simultaneous shifts in temperature, CO2, and hypoxia levels will enhance sensitivity to environmental extremes relative to a change in just one of these variables. Some interactions between these variables result from joint effects on the same physiological mechanisms. Such interactions need to be considered in terms of future increases in atmospheric CO2and its uptake by the ocean as well as in terms of currently proposed mitigation scenarios. These include purposeful injection of CO2in the deep ocean or Fe fertilization of the surface ocean, which reduces subsurface O2levels. The resulting ecosystem shifts could develop progressively, rather than beyond specific thresholds, such that effects parallel CO2oscillations. It is unsure to what extent and how quickly species may adapt to permanently elevated CO2levels by microevolutionary compensatory processes.
Linear evolution of sandwave packets
Authors: Roos P. C. , Blondeaux P. , Hulscher S. J. M. H. , Vittori G.
Published: September 2005

We investigate how a local topographic disturbance of a flat seabed may become morphodynamically active, according to the linear instability mechanism which gives rise to sandwave formation. The seabed evolution follows from a Fourier integral, which can generally not be evaluated in closed form. As numerical integration is rather cumbersome and not transparent, we propose an analytical way to approximate the solution. This method, using properties of the fastest growing mode only, turns out to be quick, insightful, and to perform well. It shows how a local disturbance develops gradually into a sandwave packet, the area of which increases roughly linearly with time. The elevation at the packet's center ultimately tends to increase, but this may be preceded by an initial stage of decrease, depending on the spatial extent of the initial disturbance. In the case of tidal asymmetry, the individual sandwaves in the packet migrate at the migration speed of the fastest growing mode, whereas the envelope moves at the group speed. Finally, we apply the theory to trenches and pits and show where results differ from an earlier study in which sandwave dynamics have been ignored.
Indian Ocean sea surface temperature variability and winter rainfall: Eastern Australia
Authors: Verdon Danielle C. , Franks Stewart W.
Published: September 2005

This study investigates the relationship between sea surface temperature (SST) variability occurring over the Indian Ocean and winter rainfall variability in eastern Australia. Six indices of SST variability are compared and their relationship to rainfall over eastern Australia is determined. An analysis of historical rainfall data for Queensland, New South Wales, and Victoria reveals that a strong relationship exists between a number of these indices and winter rainfall. In particular, anomalous SSTs over the Indonesian region provide a good indication of winter rainfall variability in eastern Australia. Additionally, this relationship is shown to hold true irrespective of potential impacts on rainfall by the El Niño‐Southern Oscillation (ENSO). A possible physical process by which the Indian Ocean SST anomalies may influence winter rainfall is proposed, involving their impact on the nature of the northwest Australian cloud band. This study demonstrates marked controls on winter climate variability comparable to that induced in summer by the better known ENSO processes and hence offers improved understanding of year‐round seasonal climates.
Decadal to century scale trends in North American snow extent in coupled atmosphere‐ocean general circulation models
Authors: Frei Allan , Gong Gavin
Published: September 2005

20th and 21st century decadal scale trends and variability in winter North American snow cover extent (NA‐SCE) are investigated using coupled atmosphere‐ocean general circulation model experiments participating in the upcoming Intergovernmental Panel on Climate Change Fourth Assessment Report. Significant between‐model variability is found, with most models underestimating mean NA‐SCE. 20th century simulations are poorly correlated with observations, and, while individual ensemble members capture the magnitude of decadal scale variability, the variability of the signal is dampened in the ensemble mean, indicating that decadal‐scale NA‐SCE variability is associated predominantly with internal model variability rather than external forcing. Two 21st century emission scenarios with realistic (moderate or significant) greenhouse gas emission rates produce decreasing NA‐SCE trends, while one unrealistic scenario with fixed concentrations produces little or no NA‐SCE trend. These results suggest that snow cover may be a sensitive indicator of climate change, and that North American snow extent will probably decrease in response to greenhouse gas emissions, although the magnitude of the response may be nonlinear.
Cold compaction of water ice
Authors: Durham William B. , McKinnon William B. , Stern Laura A.
Published: September 2005

Hydrostatic compaction of granulated water ice was measured in laboratory experiments at temperatures 77 K to 120 K. We performed step‐wise hydrostatic pressurization tests on 5 samples to maximum pressures P of 150 MPa, using relatively tight (0.18–0.25 mm) and broad (0.25–2.0 mm) starting grain‐size distributions. Compaction change of volume is highly nonlinear in P, typical for brittle, granular materials. No time‐dependent creep occurred on the lab time scale. Significant residual porosity (∼0.10) remains even at highest P. Examination by scanning electron microscopy (SEM) reveals a random configuration of fractures and broad distribution of grain sizes, again consistent with brittle behavior. Residual porosity appears as smaller, well‐supported micropores between ice fragments. Over the interior pressures found in smaller midsize icy satellites and Kuiper Belt objects (KBOs), substantial porosity can be sustained over solar system history in the absence of significant heating and resultant sintering.
Quantifying mass transfer in permeable media containing conductive dendritic networks
Authors: Gorelick Steven M. , Liu Gaisheng , Zheng Chunmiao
Published: September 2005

Tree‐like branching networks are conduits for mass transport in many natural systems. Because precisely determining conduit‐matrix mass transfer requires exact knowledge of dendrite geometries, interdomain mass exchange rates are often described using the concept of effective mass‐transfer. We present a direct association between average geometric properties of dendritic networks and mass transfer. We show that the value of the mass‐transfer rate coefficient can be estimated directly using a physically based relation that requires no knowledge of the specific network geometry.
Observations of antarctic polar stratospheric clouds by the Geoscience Laser Altimeter System (GLAS)
Authors: Palm Stephen P. , Fromm Michael , Spinhirne James
Published: September 2005

We present the first satellite lidar observations of Polar Stratospheric Clouds (PSCs). During late September and early October 2003, GLAS frequently observed type I and II PSCs over western Antarctica. At the peak of this activity on September 29 and 30 we investigate the vertical structure, horizontal coverage and general characteristics of the PSCs using the GLAS data. The PSCs were found to cover a relatively large area in a region where enhanced PSC frequency has been noted by previous PSC climatology studies. We also show near simultaneous measurements from the POAM III and SAGE II satellites that confirm the presence of type I and II PSCs in the same region. The area of PSC formation was found to coincide with the coldest temperatures and highest geopotential height in the lower stratosphere. In addition, extensive cloudiness was seen within the troposphere below the PSCs indicating that tropospheric disturbances played a role in their formation.
Secondary organic aerosol formation from isoprene photooxidation under high‐NOx conditions
Authors: Kroll Jesse H. , Ng Nga L. , Murphy Shane M. , Flagan Richard C. , Seinfeld John H.
Published: September 2005

The oxidation of isoprene (2‐methyl‐1,3‐butadiene) is known to play a central role in the photochemistry of the troposphere, but is generally not considered to lead to the formation of secondary organic aerosol (SOA), due to the relatively high volatility of known reaction products. However, in the chamber studies described here, we measure SOA production from isoprene photooxidation under high‐NOx conditions, at significantly lower isoprene concentrations than had been observed previously. Mass yields are low (0.9–3.0%), but because of large emissions, isoprene photooxidation may still contribute substantially to global SOA production. Results from photooxidation experiments of compounds structurally similar to isoprene (1,3‐butadiene and 2‐ and 3‐methyl‐1‐butene) suggest that SOA formation from isoprene oxidation proceeds from the further reaction of first‐generation oxidation products (i.e., the oxidative attack of both double bonds). The gas‐phase chemistry of such oxidation products is in general poorly characterized and warrants further study.
Solar wind‐magnetosphere‐ionosphere coupling: Neutral atmosphere effects on signal propagation
Authors: Song P. , Vasyliūnas V. M. , Ma L.
Published: September 2005

Waves that propagate between the outer magnetospheric regions (in particular the magnetopause or the magnetotail) and the ionosphere and thereby mediate the dynamic processes of the magnetosphere‐ionosphere‐thermosphere system are affected at the lower end of their paths by the interaction of the plasma with the neutral atmosphere. We use three‐fluid equations (electrons, ions, and neutral particles) to study wave propagation and derive the general dispersion relation, under the simplifying assumptions of incompressible parallel propagation in a locally uniform system. Included are the effects of ion‐neutral, electron‐neutral, and ion‐electron collisions on the electric current and on the plasma flow, as well as the effect of plasma‐neutral collisions on the neutral atmospheric flow. At low frequencies, near and below the ion‐neutral collision frequency, the properties of propagating perturbations are modified as a result of the interaction with the neutral atmosphere. Because the wavelengths may be too long for the local‐uniformity assumption to apply, the quantitative statement of the modifications may not be reliable, but their qualitative properties are clear. Wave speed becomes substantially slower than the Alfvén speed because of inertia loading by neutrals. Waves are significantly damped because of plasma‐neutral friction. Left‐handed and right‐handed waves have different dispersion properties because ion motion is inhibited much more than electron motion by collisions with neutrals. At still lower frequencies, below the neutral‐ion collision frequency, plasma and neutrals move together, leading to wave speed equal to the Alfvén speed based on the total (plasma plus neutral) mass density and to disappearance of damping and of differences between left‐handed and right‐handed dispersions. These results indicate that the coupling of ionosphere and neutral atmosphere is better described as a (frictional) neutral‐drag process rather than as Ohmic dissipation, in agreement with the conclusions of another direct study of energy equations in the ionosphere‐atmosphere system.
Evolving force balance at Columbia Glacier, Alaska, during its rapid retreat
Authors: O'Neel Shad , Pfeffer W. Tad , Krimmel Robert , Meier Mark
Published: September 2005

Changes in driving and resistive stresses play an essential role in governing the buoyancy forces that are important controls on the speed and irreversibility of tidewater glacier retreats. We describe changes in geometry, velocity, and strain rate and present a top‐down force balance analysis performed over the lower reach of Columbia Glacier. Our analysis uses new measurements and estimates of basal topography and photogrammetric surface velocity measurements made between 1977 and 2001, while assuming depth‐independent strain. Sensitivity tests show that the method is robust and insensitive to small changes in the calculation parameters. Spatial distributions of ice speed show little correspondence with driving stress. Instead, spatial patterns of ice speed exhibit a nonlinear correspondence with basal drag. Primary resistance to flow comes from basal drag, but lateral drag becomes increasingly more important throughout the retreat, which may account for observed increases in speed. Maximum basal drag is always located in a prominent constriction located ∼12 km upstream from the preretreat terminus. Once the terminus retreated into deep water off the terminal moraine marking the modern maximum extent, the upstream location of this maximum basal drag helped to promote thinning and decrease effective pressure in the lower region by limiting replenishing ice flow from upstream. An increase in both ice velocity and calving resulted, initiating what appears to be an irreversible retreat.
Close Relationships and Elevated HIV Risk Behavior: Evidence and Possible Underlying Psychological Processes
Authors: Misovich Stephen J. , Fisher Jeffrey D. , Fisher William A.
Published: September 2005

A review of research on AIDS preventive behavior indicates that minority and nonminority heterosexual adolescents and adults, gay men, injection drug users, and commercial sex workers are all less likely to practice safer sex with close relationship partners, compared with partners they perceive to be “casual” sexual partners. Because many individuals in close relationships have engaged in HIV risk behavior over extended periods of time and are unaware of their actual HIV status, practicing unprotected sexual intercourse with a committed relationship partner who is not tested for HIV appears to be a major and unrecognized source of HIV risk. This article reviews the evidence for higher levels of HIV risk behavior in close relationships and then presents relevant conceptual and empirical work to explore the psychological processes that may underlie risky sexual behavior in close relationships, using as a framework the information–motivation–behavioral skills model of preventive behavior.
Early Development of Executive Function: A Problem-Solving Framework
Authors: Zelazo Philip David , Carter Alice , Reznick J. Steven , Frye Douglas
Published: September 2005

Executive function (EF) accounts have now been offered for several disorders with childhood onset (e.g., attention-deficit/hyperactivity disorder, autism, early-treated phenylketonuria), and EF has been linked to the development of numerous abilities (e.g., attention, rule use, theory of mind). However, efforts to explain behavior in terms of EF have been hampered by an inadequate characterization of EF itself. What is the function that is accomplished by EF? The present analysis attempts to ground the construct of EF in an account of problem solving and thereby to integrate temporally and functionally distinct aspects of EF within a coherent framework. According to this problem-solving framework, EF is a macroconstruct that spans 4 phases of problem solving (representation, planning, execution, and evaluation). When analyzed into subfunctions, macroconstructs such as EF permit the integration of findings from disparate content domains, which are often studied in isolation from the broader context of reasoning and action. A review of the literature on the early development of EF reveals converging evidence for domain-general changes in all aspects of EF.
A Reexamination of the Perceptual-to-Conceptual Shift in Mental Representations
Authors: Quinn Paul C. , Eimas Peter D.
Published: September 2005

The authors discuss the origins of categorical representations in young infants, using recent evidence on the categorization of animals. This evidence suggests that mature conceptual representations for animals derive from the earliest perceptually based representations of animals formed by young infants, those based on the surface features characteristic of each species, including humans. The shift from perceptually to conceptually based representation is a gradual and continuous process marked by initial, relatively simple, perceptually based representations coming to include more and more specific values of common animal properties. Development is thus a process of enrichment by perceptual systems, including that for language, and without the need of specialized processes that alter the nature of human thought and the representation of human knowledge.
Writing Narrative Literature Reviews
Authors: Baumeister Roy F. , Leary Mark R.
Published: September 2005

Narrative literature reviews serve a vital scientific function, but few resources help people learn to write them. As compared with empirical reports, literature reviews can tackle broader and more abstract questions, can engage in more post hoc theorizing without the danger of capitalizing on chance, can make a stronger case for a null-hypothesis conclusion, and can appreciate and use methodological diversity better. Also, literature reviews can draw any of 4 conclusions: The hypothesis is correct, it has not been conclusively established but is the currently best guess, it is false, or the evidence permits no conclusion. Common mistakes of authors of literature review manuscripts are described.
Reality Negotiation: Governing One's Self and Being Governed by Others
Authors: Snyder C. R. , Higgins Raymond L.
Published: September 2005

Self-theories are posited along 2 related cognitive dimensions. First, the valence of an act varies from negative to positive. Second, the linkage to an act reflects the degree (ranging from none to high) to which one is perceived as being the causal agent for that act. Plotting these 2 dimensions, with valence reflecting the ordinate (negative at the bottom to positive at the top) and linkage reflecting the abscissa (no linkage at the left to high linkage at the right), most people have a positive self-theory regression line linking themselves most strongly to positive valence acts. A minority, however, have negative self-theories showing decreasing linkage to positive valence acts. Reality negotiation strategies are psychological mechanisms used to preserve self-theories when confronted with theory-discrepant information. These strategies are detailed, and it is shown how they ultimately foster societal control over the person.
Memory Beliefs as Social Cognition: A Reconceptualization of What Memory Questionnaires Assess
Authors: Cavanaugh John C. , Feldman Jack M. , Hertzog Christopher
Published: September 2005

Few attempts have been made to integrate research on memory beliefs across adulthood with related constructs in social cognition. This article addresses the issue of how respondents formulate answers to memory-beliefs questions from a social–cognitive perspective. We propose that reported memory beliefs represent the outcomes of a process that involves both the retrieval of previously stored information about self and about memory and on-line constructive processes. This article offers a set of assumptions that clarifies existing data on memory beliefs and generates new hypotheses regarding the interactions between beliefs about the aging process, memory, and constructs such as memory self-efficacy and how such variables combine with the on-line constructive processes to produce individual differences in responses.
Social–Cognitive Alternatives to Dissociation Theories of Hypnotic Involuntariness
Authors: Kirsch Irving , Lynn Steven Jay
Published: September 2005

Three social–cognitive models are presented as alternatives to dissociation theories of hypnotic involuntariness. In Model I, people are seen as intentionally enacting responses without being aware of the volitional quality of their acts. In Model II, hypnotic behaviors are seen as prepared responses that are triggered directly by suggestion. The first model corresponds to E. R. Hilgard's (1986) neodissociation theory and the second to K. S. Bowers's (1992) theory of dissociated control, but without positing dissociative mechanisms as explanatory constructs. These constructs are replaced by a consideration of the automaticity that is inherent in commonplace intentional behavior and the degree to which subjective experience is affected by beliefs and expectations. Finally, a composite model reconciling the contradictions between the two prior social–cognitive models is presented.
Transference in Everyday Experience: Implications of Experimental Research for Relevant Clinical Phenomena
Authors: Andersen Susan M. , Berk Michele S.
Published: September 2005

Experimental research examining the clinical concept of transference ( S. Freud, 1912/1958 ; H. S. Sullivan, 1953 ) using a social–cognitive model has demonstrated that mental representations of significant others are stored in memory and can be activated and applied in new social encounters, with consequences for cognition, evaluation, affect, motivation, expectancies, and self-evaluations ( S. M. Andersen & N. S. Glassman, 1996 ; S. M. Andersen, I. Reznik, & S. Chen, 1997 ). These findings constitute an empirical demonstration of transference in everyday social relations and suggest that transference is a normal, nonpathological process, occurring both inside and outside of psychotherapy, following basic rules of social information processing. In this article, clinical implications of this research are discussed, including how the content versus process of transference may contribute to maladaptive transference responses and the potential value of identifying triggering cues in transference in real life and in therapy, to promote more adaptive responding.
On the Intrinsic Nature of States of Consciousness: James's Ubiquitous Feeling Aspect
Authors: Natsoulas Thomas
Published: September 2005

Among problems psychologists of consciousness face is how to conceive of those mental states, events, or processes with which people have an intimate familiarity in their own case. Psychologists must not only determine the causal roles these occurrences play, but also their intrinsic properties. This article seeks to contribute to understanding what and how the conscious mental occurrences are in themselves, starting from W. James's conception of them, according to which every basic durational component of the stream, each successive state of consciousness, is an integral pulse of mentality possessing a feeling aspect and a cognitive aspect. Attention is also given to their reflexive aspect, wherein one has inner awareness of their occurrence and, often, of their type and content.
What Good Are Positive Emotions?
Authors: Fredrickson Barbara L.
Published: September 2005

This article opens by noting that positive emotions do not fit existing models of emotions. Consequently, a new model is advanced to describe the form and function of a subset of positive emotions, including joy, interest, contentment, and love. This new model posits that these positive emotions serve to broaden an individual's momentary thought–action repertoire, which in turn has the effect of building that individual's physical, intellectual, and social resources. Empirical evidence to support this broaden-and-build model of positive emotions is reviewed, and implications for emotion regulation and health promotion are discussed.
A Balance Theory of Wisdom
Authors: Sternberg Robert J.
Published: September 2005

The author presents a balance theory of wisdom. First, some alternative approaches to wisdom are reviewed, including philosophical, implicit theoretical, and explicit theoretical ones. Second, the concept of tacit knowledge and its role in wisdom are discussed. Third, a balance theory of wisdom is presented, according to which wisdom is defined as the application of tacit knowledge as mediated by values toward the achievement of a common good through a balance among multiple (a) intrapersonal, (b) interpersonal, and (c) extrapersonal interests in order to achieve a balance among (a) adaptation to existing environments, (b) shaping of existing environments, and (c) selection of new environments. This theory is compared to some other theories, and wisdom as a construct is compared to some other constructs. Measurement issues are also discussed. It is concluded that it might be worthwhile for American society to emphasize development of wisdom in schooling more than it has in the past.
Rational Errors and the Mathematical Mind
Authors: Ben-Zeev Talia
Published: September 2005

What do errors reveal about the mathematical mind? Intriguingly, errors are often logically consistent and rule based rather than being random. Investigating errors, therefore, presents an opportunity for uncovering the mental representations underlying mathematical reasoning. A useful question is whether errors break down into different categories or types. If this were the case, then one could explain a variety of seemingly different problem-solving behaviors by using only a few principles. The aim of this article is to provide a taxonomy of rule-based errors in mathematical reasoning that illustrates how a few basic mental processes may be responsible for generating myriad different errors. Implications for general processes of reasoning and problem solving are discussed.
Inherited Hypohedonia Leads to Learned Helplessness: A Conjecture Updated
Authors: Hamburg Sam R.
Published: September 2005

The reformulated learned helplessness theory posits depressogenic explanatory style (DES) as a vulnerability factor in depression. Early-life adversity has been suggested as the source of DES, but this is contradicted by empirically established features of the learned helplessness phenomenon itself and by the evidence for human resilience in the face of adversity. This article extends a conjecture first advanced by P. E. Meehl (1975) and argues that an inherited defect in hedonic capacity would be sufficient to produce DES by causing intermittent schedules of reinforcement to be experienced as extinction schedules, resulting in a pervasive and unremitting sense of helplessness. This proposed hedonic defect also provides a means for integrating the original and reformulated versions of learned helplessness theory and for integrating learned helplessness with emerging research and theory on the biology of vulnerability to depression.