bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of primary spinal neuron lineages after deletion of a major progenitor
Authors: Gallagher Betty C. , Moody Sally A.
Published: August 2004

Summry— Vertebrate embryos are able to reconstitute the body plan when early blastomeres are deleted, but it is not known whether this is accomplished by cells local to the lesion or by a readjustment of the entire pattern of the embryo. We distinguished between these two possibilities by studying which embryonic cells change primary spinal neuronal fates after deletion of a major spinal cord progenitor. After ablation of the V1.2 blastomere of the 16‐cell Xenopus embryo, the spinal cord contained normal numbers of Rohon‐Beard neurons and primary motoneurons, indicating that the remaining blastomeres numerically reconstituted these populations. Using lineage‐tracing techniques we revealed a global response: 10 out of the 15 remaining blastomeres significantly changed the number of one or both neuronal types they produced. This widespread response indicates that position in the early embryo plays an important role in regulating the production of primary spinal neurons. However, not all cells are influenced solely by position; a vegetal cell transplanted into the position of the deleted V1.2 did not take on the neuronal fate of its new position. Thus, restitution of pattern relies on a combination of positional cues and intrinsic fate restrictions.
Involvement of cytokines, chemokines and adhesion molecules in opioid analgesia
Authors: Rittner H.L. , Stein C.
Published: August 2004

Tissue destruction is accompanied by an inflammatory reaction. The inflammatory reaction leads to activation of nociceptors and the sensation of pain. Several mediators are responsible for pain and hyperalgesia in inflammation including cytokines, chemokines, nerve growth factor as well as bradykinin, prostaglandins and ATP. Simulatenously however, analgesic mediators are secreted: opioid peptides, somatostatin, endocannabinoids and certain cytokines. Opioid peptides secreted from immune cells are so far the best studied peptides in peripheral inflammatory pain control. This system is hampered for example by anti‐adhesion molecule treatment. Novel immunosuppressive drugs for treatment of autoimmune disease targetting cytokines, chemokines or adhesion molecules should therefore be evaluated for potential harmful effects on pain.
Memories of parental rearing and perceived self‐image in groups of chronic pain patients
Authors: Nordin Häkan , Eisemann Martin , Richter Jörg
Published: August 2004

Objectives The aim of this study was to analyze the relationships between perceived parental rearing styles as determining factors of self‐image in chronic pain patients, and to test the hypothesis of two different groups inherent to the pain sample.

Methods In this study, 152 patients with chronic pain participated. The sample was divided into two groups by means of hierarchical cluster analysis on the Minnesota multiphasic personality inventory, version 2. Cluster 1 comprised 116 individuals (44 men and 72 women) with a “conversion V” MMPI‐2 profile, and cluster 2 comprised 21 individuals (5 men and 16 women) with a “general elevated” MMPI‐2 profile. The patients were investigated by means of the structural analysis of social behavior (SASB), the Giessen test (GT), the locus of control scale (LOC) and the EMBU questionnaire (My memories of parental upbringing).

Results The results show significant associations between memories of parental rearing and self‐image as adults and are in line with results from previous studies describing two psychologically different groups inherent to chronic pain patients.

Conclusions The significant differences between healthy controls, pain patients and between clusters of pain patients on parental rearing scales, and the significant relationship between memories of parental rearing and self‐image provide therapists with a special approach to the treatment of chronic pain patients in accordance to social cognitive theories and the psychodynamic theoretical construct of introjection as an early process in the development of self‐images.
The causal status of pain catastrophizing: an experimental test with healthy participants
Authors: Severeijns Rudy , van den Hout Marcel A. , Vlaeyen Johan W.S.
Published: August 2004

In the current study we report findings on the effects of experimentally induced catastrophizing about pain on expected pain, experienced pain and escape/avoidance behavior during a cold pressor task in a sample of healthy participants. It was hypothesized that increasing the level of catastrophizing would result in a higher level of expected pain, a higher level of experienced pain, and a shorter duration of ice‐water immersion. Also, it was hypothesized that these relations might be stronger for participants who already catastrophized about pain prior to the experiment.

The results demonstrated that despite the successful attempt to induce catastrophizing, this neither significantly affected expected pain, experienced pain, and duration of ice‐water immersion, nor were these relations moderated by the pre‐experimental level of catastrophizing.

Although the level of catastrophizing was successfully manipulated, more similar experiments are necessary in order to give a more definite answer on the possible causal status of pain catastrophizing.
Psychiatric comorbidity in medication overuse headache patients with pre‐existing headache type of episodic tension‐type headache
Authors: Atasoy Huseyin Tugrul , Atasoy Nuray , Unal Aysun Eroglu , Emre Ufuk , Sumer Murat
Published: August 2004

Background: Medication overuse headache (MOH) mostly evolves from migraine and episodic tension‐type headache (ETTH). Chronic tension‐type headache (CTTH) is another headache type that evolves over time from ETTH. It is well known that psychiatric comorbidity is high in MOH patients.

Aim: To investigate the frequency of psychiatric comorbidity, and the intensity of depression and anxiety in MOH patients evolving from ETTH and to compare results with CTTH patients and MOH patients evolving from migraine.

Methods: Twenty‐eight CTTH (Group C) and 89 MOH patients were included into the study. MOH patients were divided into two groups according to their pre‐existing headache types: MOH patients with pre‐existing ETTH (Group E, n = 31), and with pre‐existing migraine (Group M, n = 58). All patients were interviewed with a psychiatrist and SCID‐CV and SCID‐II were applied. Beck Anxiety Inventory and Beck Depression Inventory scales were also performed.

Results: Eleven patients (39.3%) in Group C, 21 patients (67.7%) in Group E, and 31 patients (53.7%) in Group M were diagnosed to have comorbid psychiatric disorders. The psychiatric comorbidity was found significantly higher in Group E than Group C. In Group E, mood disorders were found significantly higher, but the difference between the two groups with regard to anxiety disorders was insignificant. Mean depression scores were significantly higher in Group E than Group C. The mostly diagnosed type was obsessive‐compulsive personality disorder in all the three groups, and was statistically significant in Group M than Group C.

Conclusion: Psychiatric comorbidity in MOH patients with pre‐existing ETTH is common as in those with pre‐existing migraine headache and MOH with regard to developing psychiatric disorders should be interpreted as a risk factor in chronic daily headache patients.
Transport of somatostatin and substance P by human P‐glycoprotein
Authors: Uchiyama-Kokubu Noriko , Naito Mikihiko , Nakajima Motowo , Tsuruo Takashi
Published: August 2004

P‐glycoprotein is an efflux pump for a broad spectrum of hydrophobic agents. We found that bioactive peptides including somatostatin and substance P inhibit ATP‐dependent vincristine binding to P‐glycoprotein‐overexpressing K562/ADM membrane vesicles. Some of these bioactive peptides including somatostatin stimulate basal ATPase activity of P‐glycoprotein; in contrast, other peptides including substance P inhibit it. The K562/ADM membrane vesicles showed an ATP‐dependent, osmotically sensitive uptake of somatostatin and substance P, which was inhibited by valspodar, an inhibitor of P‐glycoprotein. These findings suggested that certain bioactive peptides such as somatostatin and substance P directly interact with human P‐glycoprotein as endogenous substrates for P‐glycoprotein‐mediated transport.
Coupling between vesicle shape and the non‐homogeneous lateral distribution of membrane constituents in Golgi bodies
Authors: Iglič Aleš , Fošnarič Miha , Hägerstrand Henry , Kralj-Iglič Veronika
Published: August 2004

In this work, a hypothesis is presented that could explain the non‐homogeneous lateral distribution of membrane components in Golgi vesicles. It is shown that the non‐homogeneous lateral distribution of membrane components and the specific flattened shape of Golgi vesicles are strongly coupled. In agreement with experimental evidence, it is indicated that some of the membrane components may be concentrated mainly on the curved bulbous rims of the Golgi vesicles, while the other components are distributed predominantly in their flat central part.
Crystallographic studies of shikimate binding and induced conformational changes in Mycobacterium tuberculosis shikimate kinase
Authors: Dhaliwal Balvinder , Nichols Charles E. , Ren Jingshan , Lockyer Michael , Charles Ian , Hawkins Alastair R. , Stammers David K.
Published: August 2004

The X‐ray crystal structure of Mycobacterium tuberculosis shikimate kinase (SK) with bound shikimate and adenosine diphosphate (ADP) has been determined to a resolution of 2.15 Å. The binding of shikimate in a shikimate kinase crystal structure has not previously been reported. The substrate binds in a pocket lined with hydrophobic residues and interacts with several highly conserved charged residues including Asp34, Arg58, Glu61 and Arg136 which project into the cavity. Comparisons of our ternary SK–ADP–shikimate complex with an earlier binary SK–ADP complex show that conformational changes occur on shikimate binding with the substrate‐binding domain rotating by 10°. Detailed knowledge of shikimate binding is an important step in the design of inhibitors of SK, which have potential as novel anti‐tuberculosis agents.
The role of the cyclic peptide backbone in the anti‐HIV activity of the cyclotide kalata B1
Authors: Daly Norelle L. , Gustafson Kirk R. , Craik David J.
Published: August 2004

The plant cyclotides, the largest known family of circular proteins, have tightly folded structures and a range of biological activities that lend themselves to potential pharmaceutical and agricultural applications. Based on sequence homology, they are classified into the bracelet and Möbius subfamilies. The bracelet subfamily has previously been shown to display anti‐HIV activity. We show here that a member of the Möbius subfamily, kalata B1, also exhibits anti‐HIV activity despite extensive sequence differences between the subfamilies. In addition, acyclic permutants of kalata B1 displayed no anti‐HIV activity, suggesting that this activity is critically dependent on an intact circular backbone.
Scaphotrapeziotrapezoid (STT)-Arthrodesis in Kienböck’s Disease
Authors: MEIER R. , VAN GRIENSVEN M. , KRIMMER H.
Published: August 2004

This study reviews the results of 59 of 84 patients with severe Kienböck’s disease who were treated with STT fusion. The average follow-up period was 4 (ranges: 2–8) years.

The average arc of wrist extension and flexion was 67° (60% of the contralateral side, 81% of pre-operative range) and that of ulnar and radial deviation was 31° (52% of the contralateral side, 56% of pre-operative range). Pre-operative pain values (VAS) were 56 (non-stress) and 87 (stress) and were significantly higher than the postoperative values of 12 (non-stress) and 41 (stress). Grip strength improved from 45 kPa pre-operatively to 52 kPa postoperatively. The mean modified Mayo wrist score was 63 points. The patients reported low disability in the DASH scores, with an average of 28 points.

Our data show that STT fusion is a reliable and effective treatment for pain relief and offers a good functional result in advanced stages of Kienböck’s disease. However the long-term effect of this procedure on radioscaphoid and other intercarpal joints is yet to be determined.
Motion‐based tendon diagnosis using sequence processing of ultrasound images
Authors: Ofer Nir , Akselrod Solange , Nyska Meir , Werner Miriam , Glaser Ernesto , Shabat Shay
Published: August 2004

Degenerative or pre‐degenerative processes in the tendon, which could lead to a spontaneous rupture, are well known problems, especially among athletes. Existing non‐invasive diagnostic methods are mainly based on subjective analysis of static images of the tendon, but in many cases the degeneration cannot be diagnosed in time. Combining a set of existing image processing techniques, a tool for tracking the in vivo motion of a tendon imaged with dynamic ultrasound was implemented.

A group of subjects that had undergone a degenerative rupture of their Achilles tendon, one subject with a traumatic rupture, and a group of control subjects were all tested. Using the motion information that was obtained from both tendons of all subjects, we developed an automatic test that examines the symmetrical properties of the tendon's motion, and defined a negative asymmetry property that could be quantified as a score.

This score was found to be significantly more enhanced in the post‐operative tendons (18.0 ± 19.0) than in the contra‐lateral healthy tendons of the same subjects (3.9 ± 4.6). In the single traumatic rupture subject, this effect was not found (0.0). This leads us to believe that the negative asymmetry of tendon motion may be associated with degenerative or pre‐degenerative processes in the tendon. Also, the mean degree of negative asymmetry in the healthy tendons of post‐operative subjects (3.9 ± 4.6) was found to be higher than that of healthy tendons of the control group (1.5 ± 1.8). This finding may be associated with the fact that tendons that are contra‐lateral to spontaneously ruptured tendons have a higher risk of developing degenerative processes. The method presented here is objective, low‐cost, non‐invasive and possibly more sensitive than existing non‐invasive techniques. © 2004 Orthopaedic Research Society. Published y Elsevier Ltd. All rights reserved.
Hornblende etching and quartz/feldspar ratios as weathering and soil development indicators in some Michigan soils
Authors: Mikesell Leslie R. , Schaetzl Randall J. , Velbel Michael A.
Published: August 2004

Weathering can be used as a highly effective relative age indicator. One such application involves etching of hornblende grains in soils. Etching increases with time (duration) and decreases with depth in soils and surficial sediments. Other variables, related to intensity of weathering and soil formation, are generally held as constant as possible so as to only minimally influence the time–etching relationship. Our study focuses on one of the variables usually held constant–climate–by examining hornblende etching and quartz/feldspar ratios in soils of similar age but varying degrees of development due to climatic factors. We examined the assumption that the degree of etching varies as a function of soil development, even in soils of similar age. The Spodosols we studied form a climate-mediated development sequence on a 13,000-yr-old outwash plain in Michigan. Their pedogenic development was compared to weathering-related data from the same soils. In general, soils data paralleled weathering data. Hornblende etching was most pronounced in the A and E horizons, and decreased rapidly with depth. Quartz/feldspar ratios showed similar but more variable trends. In the two most weakly developed soils, the Q/F ratio was nearly constant with depth, implying that this ratio may not be as effective a measure as are etching data for minimally weathered soils. Our data indicate that hornblende etching should not be used as a stand-alone relative age indicator, especially in young soils and in contexts where the degree of pedogenic variability on the geomorphic surface is large.
Changes in mothers' basic beliefs following a child's bone marrow transplantation: The role of prior trauma and negative life events
Authors: Rini Christine , Manne Sharon , DuHamel Katherine N. , Austin Jane , Ostroff Jamie , Boulad Farid , Parsons Susan K. , Martini Richard , Williams Sharon , Mee Laura , Sexson Sandra , Redd William H.
Published: August 2004

This longitudinal study examined the relation between life stress and basic beliefs about self‐worth and the benevolence and meaningfulness of the world among mothers of children undergoing bone marrow transplantation (BMT). One hundred mothers completed study measures during the child's hospitalization for BMT and 1 year later. Prior trauma and recent negative events were associated with basic beliefs during hospitalization and also with changes in basic beliefs in the subsequent year, with distress mediating some of these relations. Findings also demonstrated relations between basic beliefs and physical and mental functioning. However, each basic belief exhibited different relations with study variables, suggesting the need to investigate them separately.
Numerical modeling of geophysical granular flows: 1. A comprehensive approach to granular rheologies and geophysical multiphase flows
Authors: Dartevelle Sébastien
Published: August 2004

Geophysical granular materials display a wide variety of behaviors and features. Typically, granular flows (1) are multiphase flows, (2) are very dissipative over many different scales, (3) display a wide range of grain concentrations, and (4), as a final result of these previous features, display complex nonlinear, nonuniform, and unsteady rheologies. Therefore the objectives of this manuscript are twofold: (1) setting up a hydrodynamic model which acknowledges the multiphase nature of granular flows and (2) defining a comprehensive rheological model which accounts for all the different forms of viscous dissipations within granular flows at any concentration. Hence three important regimes within granular flows must be acknowledged: kinetic (pure free flights of grain), kinetic‐collisional, and frictional. The momentum and energy transfer will be different according to the granular regimes, i.e., strain rate dependent in the kinetic and kinetic‐collisional cases and strain rate independent in the frictional case. A “universal” granular rheological model requires a comprehensive unified stress tensor able to adequately describe viscous stress within the flow for any of these regimes, and without imposing a priori what regime will dominate over the others. The kinetic‐collisional viscous regime is defined from a modified Boltzmann's kinetic theory of dense gas. The frictional viscous regime is defined from the plastic potential and the critical state theories which account for compressibility of granular matter (e.g., dilatancy, consolidation, and critical state). In the companion paper [Dartevelle et al., 2004] we will introduce a multiphase computer code, (G)MFIX, which accounts for all the granular regimes and rheology and present typical simulations of diluted (e.g., plinian clouds) and concentrated geophysical granular flows (i.e., pyroclastic flows and surges).
Numerical modeling of geophysical granular flows: 2. Computer simulations of plinian clouds and pyroclastic flows and surges
Authors: Dartevelle Sébastien , Rose William I. , Stix John , Kelfoun Karim , Vallance James W.
Published: August 2004

Geophysical granular flows display complex nonlinear, nonuniform, and unsteady rheologies, depending on the volumetric grain concentration within the flow: kinetic, kinetic‐collisional, and frictional. To account for the whole spectrum of granular rheologies (and hence concentrations), we have used and further developed for geophysical‐atmospheric applications a multiphase computer model initially developed by U.S. Department of Energy laboratories: (Geophysical) Multiphase Flow with Interphase Exchange. As demonstrated in this manuscript, (G)MFIX can successfully simulate a large span of pyroclastic phenomena and related processes: plinian clouds, pyroclastic flows and surges, flow transformations, and depositional processes. Plinian cloud simulations agree well with the classical plume theory and historical eruptions in the upper altitude of the cloud (HT) versus mass flux diagram. At high mass flux (>107 kg/s), plinian clouds pulsate periodically with time because of the vertical propagations of acoustic‐gravity waves within the clouds. The lowest undercooled temperature anomalies measured within the upper part of the column can be as low as −18 K, which agrees well with El Chichón and Mt. St. Helens eruptions. Vertical and horizontal speed profiles within the plinian cloud compare well with those inferred from simple plume models and from umbrella experiments. Pyroclastic flow and surge simulations show that both end‐members are closely tight together; e.g., an initially diluted flow may generate a denser basal underflow, which will eventually outrun the expanded head of the flow. We further illustrate evidence of vertical and lateral flow transformation processes between diluted and concentrated flows, particularly laterally from a turbulent “maintained over time fluidized zone” near source. Our comprehensive granular rheological model and our simulations demonstrate that the main depositional process is mainly a progressive vertical aggradation.
Effective field method for seismic properties of cracked rocks
Authors: Levin V. , Markov M. , Kanaun S.
Published: August 2004

A self‐consistent scheme called the effective field method (EFM) is developed for the calculation of the velocities of elastic waves propagating in cracked rocks. The latter are simulated by a homogeneous elastic medium containing thin ellipsoidal inhomogeneities (crack‐like inclusions), with material much softer than the one of the medium. Spatial distribution of cracks in the medium is taken into account via a special two‐point correlation function of the random crack field. The results of the calculation of the elastic properties of rocks containing isotropic fields of cracks and rocks with some nonisotropic spatial distributions of cracks are presented. Predictions of the EFM are compared with available experimental data and with predictions of other self‐consistent methods (the effective medium approximation and the differential effective medium approximation).
A Lagrangian study of surface pCO2 dynamics in the eastern equatorial Pacific Ocean
Authors: DeGrandpre Michael D. , Wanninkhof Rik , McGillis Wade R. , Strutton Peter G.
Published: August 2004

We characterized pCO2 variability on hourly to weekly timescales during the 14‐day GasEx‐2001 Lagrangian drifter experiment in the eastern equatorial Pacific Ocean. Underway pCO2 was recorded at 5 m depth as the ship closely followed a drogued drifter. Dissolved O2 (DO) was measured at 10 and 15 m depths using in situ sensors deployed on the drogue. Diel pCO2 and DO variability is evaluated using a simple model that accounts for air‐sea exchange, vertical mixing, heating, and net community metabolism. Mixed‐layer depths and local (vertical) entrainment are estimated with the Price Weller Pinkel (PWP) mixed‐layer model. The mean observed pCO2 was 472.0 ± 1.8 μatm with a diel increase of 2–6 μatm on most days, near coincident in time with the diel peak in temperature. The biogeochemical model reveals that heating was the primary source of diel pCO2 variability, but net community production and depletion of CO2 in the shallow warm layer due to air‐sea gas exchange reduced the heating‐driven peak by ∼1–4 and 1–2 μatm each day, respectively. The same model parameterizations also accurately predict the diel DO amplitude. In the model, atmospheric exchange depletes total CO2 and DO in the surface layer, and the depleted water is mixed with the isolated underlying water during nocturnal convection. The 10‐ and 15‐m DO time series corroborate these predicted dynamics. Over the 14‐day study, net heating offset the expected ∼14 μatm decrease due to air‐sea CO2 exchange and net community production, resulting in a nearly constant mean pCO2. Consequently, net heating acts to sustain high air‐sea CO2 fluxes in the upwelled equatorial Pacific water as the water advects westward in the South Equatorial Current.
Electric field measurements in noctilucent clouds
Authors: Holzworth Robert H. , Goldberg Richard A.
Published: August 2004

Two rockets were flown through noctilucent clouds (NLC) during the Distribution and Role of Particles in the Polar Summer Mesosphere using Coordinated Rocket, Radar, and Lidar Techniques (DROPPS) rocket experiment from Andøya Rocket Range, Norway, in July 1999. Each rocket was equipped with three‐axis, double‐double, high‐impedance Langmuir probes (12 probes each flight) and produced unprecedented resolution of the electric potential distribution around the rockets in and near both a weak NLC (DROPPS1) and a very strong NLC (DROPPS2). Detailed analysis of the vehicle interaction during the weak NLC encounter, in which no large geophysical electric fields were detected [Holzworth et al., 2001], provided a basis for understanding the strong NLC encounter by DROPPS2, where geophysical electric fields reached 3 V m−1. The electric field orientation is shown to be vertically downward. In the case of the strong NLC encounter a layer of excess positive charge at the top of the layer reached a density of 2 pC m−3, deduced from the sharp field gradient. The total integrated potential drop through the NLC was 2 kV.
Modeling fluvial erosion and deposition on continental shelves during sea level cycles
Authors: Fagherazzi Sergio , Howard Alan D. , Wiberg Patricia L.
Published: August 2004

A numerical model has been developed to predict the evolution and degree of incision and deposition by fluvial channels on the continental shelf during sea level cycles. Rainfall‐runoff, mass wasting processes, and fluvial sediment entrainment and transport are simulated using the detachment‐limited model of Howard [1994] on a grid that represents the morphology of the continental shelf and corresponding coastal plain. The model is coupled with a deltaic module for sediment deposition in the ocean and a fluctuating sea level that mimics climatic changes on a ∼104 year timescale. The model indicates that the detailed structure of sea level oscillations has a strong influence upon sediment redistribution and channel development on the shelf. In particular, high‐frequency sea level oscillations increase fluvial incision in the terminal reaches of the rivers due to rapid downcutting during the low stands of the oscillation. It is shown that the increment of incision at the river mouth is directly proportional to the oscillation amplitude. Furthermore, simulations indicate that an increase in river sediment load driven by climatic change favors channel avulsion with the formation of new fluvial incisions on the shelf. Results also show the strong influence of shelf morphology on establishing channel networks during sea level low stands.
A combined parameter scaling and inverse technique to upscale the unsaturated hydraulic parameters for heterogeneous soils
Authors: Zhang Z. Fred , Ward Andy L. , Gee Glendon W.
Published: August 2004

Determining a large number of soil hydraulic parameters for heterogeneous soils remains a challenge because inverting for too many parameters can lead to parameter values that are nonunique. Furthermore, such inversions may need very long simulation times, for example, months or more when inverting field‐scale problems. In this research, a combined parameter scaling and inverse technique (CPSIT) is proposed to upscale hydraulic parameters from the local scale to the field scale. The CPSIT approach includes two steps: (1) parameter scaling and (2) inverse modeling. In step 1 the number of parameters to be estimated at field scale (FS) is reduced by applying parameter scaling whereby a heterogeneous soil is treated as a composition of multiple equivalent homogeneous media (EHMs). In step 2 the FS parameters for the reference EHM are determined using the inverse technique and observations from well‐designed field experiments. The advantages of the CPSIT approach are that the number of parameters to be inverted is reduced by a factor of the number (M) of EHMs, and the simulation time is reduced by a factor of about M2. The CPSIT approach was tested by upscaling the hydraulic parameters using a field injection experiment at the Hanford Site. Results show that when the CPSIT upscaled parameters were used to simulated flow, the mean squared residual was reduced by 83.2% relative to that when the local‐scale parameters were used.
Strengthening river basin institutions: The Global Environment Facility and the Danube River Basin
Authors: Gerlak Andrea K.
Published: August 2004

Increased international attention to water resource management has resulted in the creation of new institutional arrangements and funding mechanisms as well as international initiatives designed to strengthen river basin institutions. The Global Environment Facility's (GEF) International Waters Program is at the heart of such novel collaborative regional approaches to the management of transboundary water resources. This paper assesses GEF‐led efforts in the Danube River Basin, GEF's most mature and ambitious projects to date. It finds that GEF has been quite successful in building scientific knowledge and strengthening regional governance bodies. However, challenges of coordinating across expanding participants and demonstrating clear ecological improvements remain. GEF‐led collaborative activities in the Danube River Basin reveal three critical lessons that can inform future river basin institution building and decision making, including the importance of appropriately creating and disseminating scientific data pertaining to the river system, the need for regional governance bodies for integrated river basin management, and the necessity to address coordination issues throughout project planning and implementation.
Methane fluxes between terrestrial ecosystems and the atmosphere at northern high latitudes during the past century: A retrospective analysis with a process‐based biogeochemistry model
Authors: Zhuang Q. , Melillo J. M. , Kicklighter D. W. , Prinn R. G. , McGuire A. D. , Steudler P. A. , Felzer B. S. , Hu S.
Published: August 2004

We develop and use a new version of the Terrestrial Ecosystem Model (TEM) to study how rates of methane (CH4) emissions and consumption in high‐latitude soils of the Northern Hemisphere have changed over the past century in response to observed changes in the region's climate. We estimate that the net emissions of CH4 (emissions minus consumption) from these soils have increased by an average 0.08 Tg CH4 yr−1 during the twentieth century. Our estimate of the annual net emission rate at the end of the century for the region is 51 Tg CH4 yr−1. Russia, Canada, and Alaska are the major CH4 regional sources to the atmosphere, responsible for 64%, 11%, and 7% of these net emissions, respectively. Our simulations indicate that large interannual variability in net CH4 emissions occurred over the last century. Our analyses of the responses of net CH4 emissions to the past climate change suggest that future global warming will increase net CH4 emissions from the Pan‐Arctic region. The higher net CH4 emissions may increase atmospheric CH4 concentrations to provide a major positive feedback to the climate system.
Tropospheric influence on the diminished Antarctic ozone hole in September 2002
Authors: Nishii Kazuaki , Nakamura Hisashi
Published: August 2004

In late September of 2002, the first recorded major sudden stratospheric warming occurred over Antarctica, leading to sudden breakdown of the cold polar vortex and the collapse of the ozone hole. Our diagnosis reveals that the warming was associated with propagation of a Rossby wavepacket from a prominent tropospheric blocking ridge over the South Atlantic into the stratospheric polar‐night jet that had already weakened unusually. The blocking developed from anomalies that had formed as a component of another Rossby wavetrain that appeared to be forced in mid‐September by anomalous deep cumulus convection in the South Pacific Convergence Zone.
Spatially‐resolved spectroscopy at 1.6 μm of Titan's atmosphere and surface
Authors: Ádámkovics M. , de Pater I. , Roe H. G. , Gibbard S. G. , Griffith C. A.
Published: August 2004

We present spatially‐resolved, low‐resolution (λ/Δλ ∼ 1,500) spectroscopy of the leading hemisphere of Titan in the H‐band (1.5–1.7 μm) using adaptive optics. Spatial variations of surface albedo are observed in images at 1.55–1.57 μm, which are clearly distinct from stratospheric haze. There is a significant increase in albedo around the southern (summer) pole at 1.62 μm. Using a plane‐parallel radiative transfer model to fit the observed spectra, we find a 61% increase in tropopause haze opacity (τ = 0.100 from 30–40 km) around the southern pole relative to the rest of the disk (where τ = 0.062 from 30–40 km).
Multidecadal variations of Fremantle sea level: Footprint of climate variability in the tropical Pacific
Authors: Feng Ming , Li Yun , Meyers Gary
Published: August 2004

Coastal sea level at Fremantle, Western Australia is strongly influenced by trade wind variations in the tropical Pacific, due to the existence of equatorial and coastal wave guides. Corroborated with low‐pass filtered Southern Oscillation Index (SOI‐M), Pacific Decadal Oscillation (PDO) causes high Fremantle sea levels during positive SOI‐M regimes (with more frequent La Niña events) and low sea levels during negative SOI‐M regimes (with more frequent El Niño events), due to enhanced and slackened trade winds. The multidecadal variation of the Fremantle sea level obscures its long‐term rising trend during the 1950's to mid 1990's. Statistical regression models are used to describe relationships between the multidecadal sea level variation and SOI‐M, in an attempt to separate natural climate variability and climate change effects. A non‐parametric regression model reveals a nonlinear relationship, likely due to different responses of the sea level (upper‐ocean) to the El Niño and La Niña events.
Investigate the impacts of assimilating satellite rainfall estimates on rainstorm forecast over southwest United States
Authors: Xu Jianjun , Gao X. , Xiao Qingnong , Sorooshian S.
Published: August 2004

Using the MM5‐4DVAR system, a monsoon rainstorm case over southern Arizona (5–6 August 2002) was investigated for the influence of assimilating satellite rainfall estimates on precipitation forecasts. A set of numerical experiments was conducted with multiple configurations including using 20‐km or 30‐km grid distances and none or 3‐h or 6‐h assimilation time windows. Results show that satellite rainfall assimilation can improve the rainstorm‐forecasting pattern and amount to some extent. The minimization procedure of 4DVAR is sensitive to model spatial resolution and the assimilation time window. The 3‐h assimilation window with hourly rainfall data works well for the 6‐h forecast, and for 12‐h or longer forecasts, a 6‐h assimilation window will be requested.
Rotation rate of Saturn's interior from magnetic field observations
Authors: Giampieri Giacomo , Dougherty Michele K.
Published: August 2004

Analysis of magnetic field data from the Pioneer 11, Voyager 1 and Voyager 2 spacecraft produced the first models of Saturn's internal field. One striking feature of these models is the lack of non axisymmetric terms, which poses strong constraints on the dynamo mechanism. Resolution of the internal field using magnetic field data from different epochs is complicated by the uncertainty in our knowledge of the planetary rotation rate. By reanalyzing the flyby data, using modern inversion techniques, we derive the first tentative direct measurement of the rotation rate of the magnetic field. The measured rotation period agrees within 0.6 s with the value obtained from remote radio emission measurements, and its uncertainty is reduced to ±2.4 s. From an inversion of all available magnetic field data, we conclude that it is premature to exclude the presence of non‐axisymmetric terms when describing the internal planetary field, and in particular we find a significant dipole tilt of 0.17°.
Planetary waves and variability of the semidiurnal tide in the mesosphere and lower thermosphere over Esrange (68°N, 21°E) during winter
Authors: Pancheva Dora V. , Mitchell Nicholas J.
Published: August 2004

The main features of the planetary waves and the variability of the semidiurnal tide with planetary wave periods observed by meteor radar over Esrange (68°N, 21°E) have been investigated. The interval of 39 months covering continuous measurements from October 1999 to December 2002 has been examined. The planetary waves most frequently observed by meteor radar measurements in the mesosphere and lower thermosphere (80–100 km) over Esrange are: 5‐, 8‐ to 10‐, 16‐, and 23‐day waves (the quasi‐2‐day wave is excluded in this study). They are strongly amplified in the winter. Some differences between high‐ and middle‐latitude planetary waves notwithstanding, the 5‐, 10‐, and 16‐day waves are most probably related to the well‐known normal mode. There are some reasons to believe that the vertically upward propagating 23‐day wave could be generated by solar forcing. The variability of the semidiurnal tide with periods of planetary waves has been thoroughly studied as well. It is found that in the winter when the planetary waves are significantly amplified, a very strong periodic variability of the semidiurnal tide is observed as well. This result indicates that the most probable mechanism responsible for the periodic tidal variability during winter is in situ nonlinear coupling between tides and planetary waves. Two winter periods have been examined (1999/2000 and 2001/2002) in order to find strong evidence supporting this suggestion. The validity of the frequency, phase, and vertical wavenumber (wavelength) relationship between the prime (the planetary wave and semidiurnal tide) and secondary waves has been established. The novel aspect of this work is that we show for the first time that the calculated vertical structures (vertical wavelengths) of the sum and difference secondary waves, which have very close periods, are actually very different.
Climate sensitivity to black carbon aerosol from fossil fuel combustion
Authors: Roberts David L. , Jones Andy
Published: August 2004

Black carbon aerosol particles from fossil fuel combustion are good absorbers of solar radiation and hence exert a positive radiative forcing, reinforcing the warming due to anthropogenic increases in CO2 and other greenhouse gases. However, it is unclear how the climate sensitivity to black carbon aerosol forcing compares with the sensitivity to greenhouse gas forcing. Here we investigate this question using the HadSM4 configuration of the Hadley Centre climate model, extended by the addition of interactive black carbon and sulphate aerosol schemes. The results confirm earlier suggestions that the climate sensitivities are not necessarily similar and indicate that the black carbon sensitivity may be weaker. Possible reasons for this are explored by studying several feedback mechanisms operating in the model.
Impact of heterogeneity, bed forms, and stream curvature on subchannel hyporheic exchange
Authors: Cardenas M. Bayani , Wilson J. L. , Zlotnik V. A.
Published: August 2004

Advection through hyporheic zones (HZ) consisting of heterogeneous channel bend streambed deposits and their equivalent homogenous medium was investigated using finite difference groundwater flow and transport simulations and forward particle tracking. The top prescribed head boundary was varied in order to mimic various stream channel head distributions resulting from the presence of bed forms and channel curvature. Flux calculations show that heterogeneity causes significant additional HZ flux compared to an equivalent homogenous medium. However, the major cause of HZ flux is a spatially periodic (sinusoidal) head distribution along the boundary, representing the effect of bed forms. The additional influence of heterogeneity on the total channel‐bed exchange and the overall HZ geometry are increased when boundary head sinusoidal fluctuation is more subdued. We present dimensionless numbers that summarize these relationships. Heterogeneity's influence is further magnified by considering the effect of channel curvature on boundary heads. The simulations illustrate the dynamic influence of heterogeneity on the hyporheic zone since the various head boundaries employed in our modeling efforts are a proxy for different surface water conditions and bed form states that may occur during a single flood. Furthermore, we show that residence times (total tracking times) of particles originating from the streambed follow a lognormal distribution. In the presence of heterogeneity, residence times can decrease or they can increase compared to residence times for homogeneous conditions depending on the relative positions of the heterogeneities and the bed forms. Hence streambed heterogeneity and stream curvature, factors often neglected in previous modeling efforts, combine with bed form configuration to dynamically determine HZ geometry, fluxes, and residence time distributions.
Steelscreen.com: Why it is not Everywhere in B2B and the Role of the CEO in ‘it’
Authors: Subirana Brian
Published: August 2004

This case is intended to serve as the basis for one or two sessions of an introductory Information Technology course at an MBA program or for one session at a senior executive program. The aim is to address what needs to be known by general managers in terms of technology and at the same time serve as an introduction for those who want to deepen their knowledge in business-to-business (B2B) technologies. Thus, it is intended to cover basic technology principles and concepts essential for any CEO/MBA. It also covers key business concepts that are impacted by information technology such as industry convergence and B2B. The approach we suggest be taken with this case is an integrative one where both technology and business concepts are intermingled throughout the class discussion. An essential ingredient of this approach is to provide a business rational for why technology matters - using this case in the first session before drilling-down into the more specific technology details of XML and metadata in a possible second session. We have worked on other cases to extend this approach to a full-scale introductory MBA/senior executive class. There are two unique features of this approach. First, it is neither technology centric nor business centric. Instead, it links executive decisions with solid information technology fundamentals. Second, our approach would be concise not requiring more than 200 pages of core case material for a full 25-session course. We believe this is an important feature because MBA-style audience base does not go into a CIO career path most of the times and will therefore not be able to afford the amount of time a longer approach would require.
Influence of buffer layer thickness on memory effects of SrBi2Ta2O9∕SiN∕Si structures
Authors: Han Jin-Ping , Koo Sang-Mo , Richter Curt A. , Vogel Eric M.
Published: August 2004

We deposited SrBi2Ta2O9 (SBT) thin films on silicon–nitride (SiN) buffered Si(100) substrates to form metal–ferroelectric–insulator–semiconductor structures and observed a significant influence of the buffer layer thickness on the magnitude and direction of the capacitance–voltage (C–V) memory window. As the SiN buffer layer thickness was decreased from 6nm to 2nm, the C–V memory hysteresis direction changed from memory direction dominated by ferroelectric polarization (i.e., counterclockwise for n-Si) to a trapping-related hysteresis direction (i.e., clockwise for n-Si). The memory windows for both cases exhibited a similar temperature dependence. The memory window approached zero at temperatures from 340°C to 380°C, which corresponds to the Curie temperature (TC) of the ferroelectric SBT films. When the temperature was returned to room temperature, the hysteresis windows were recovered. A detailed study has led us to believe that the switching of polarization of the ferroelectric SBT plays a key role in the observed temperature dependence, for both the ferroelectric polarization-dominated and the trapping-dominated memory window.
Apparatus for high temperature magnetostriction measurement of bulk samples
Authors: Lorenz B. E. , Graham C. D.
Published: August 2004

A relatively simple and inexpensive apparatus for the measurement of magnetostriction in bulk samples at room temperature and above is described. A laser beam directed into a four-quadrant photodiode is partially blocked by the free end of the strip sample. When the sample changes length under the influence of an applied field, the output of the photodiode segments is unbalanced, producing a signal that is proportional to the change in length over a range of about 100 μm. The laser beam is modulated at 1 kHz, and the photodiode signal measured with a lock-in amplifier. The sample can be moved vertically with a fine screw thread, which is used both for calibration and to offset the effect of thermal expansion. The samples are metallic strips 10 cm long by about 6 mm wide and generally about 0.35 mm thick. They can be heated in air to a maximum temperature of about 700 °C. The sensitivity of the apparatus is about ±2 με(±2×10−6) at room temperature, falling to about ±5 με at 700 °C, which is adequate for strongly magnetostrictive materials. Measurements have been made on several Fe–Co alloys, as well as Fe, Ni, and Ni–Fe alloys.
Choosing a preamplifier for tuning fork signal detection in scanning force microscopy
Authors: Jahncke C. L. , Brandt O. , Fellows K. E. , Hallen H. D.
Published: August 2004

In scanning probe microscopy, it is critical to maintain small probe sample separations for high resolution imaging. Quartz crystal tuning forks are typically used for detecting shear forces in near-field scanning optical microscopy and normal forces in other atomic force-related microscopies. In this article we compare several tuning fork based detection schemes to determine which solution gives the best signal to noise ratio. The high impedance and low signals produced by the tuning fork necessitate care in selection of an appropriate preamplifier. We find that a carefully guarded voltage preamplifier sensing a mechanically driven tuning fork performs the best, but an electrically driven fork with a current preamplifier offers simpler construction with only 25% lower signal to noise ratio on average.
Production and characterization of polymer microcantilevers
Authors: McFarland Andrew W. , Poggi Mark A. , Bottomley Lawrence A. , Colton Jonathan S.
Published: August 2004

This work describes the production of microcantilever beams via a solvent casting technique. The beams produced had dimensions of roughly 500 by 50 by 2 μm (length, width, and thickness, respectively). A subset of the beams produced were characterized and were shown to have comparable dynamic mechanical behavior as that of existing ceramic and photopolymer microcantilevers.
Counting photoelectrons in the response of a photomultiplier tube to single picosecond light pulses
Authors: Zambra Guido , Bondani Maria , Spinelli Alessandro S. , Paleari Fabio , Andreoni Alessandra
Published: August 2004

We demonstrate the capability of a commercial photomultiplier to produce distinguishable anodic-pulse charge values when 1, 2, or more photoelectrons leave the cathode within a time shorter than the pulse-response duration. We propose a method for precise reconstruction of the photoelectron statistics from the measured pulse-height spectra and discuss applications to the characterization of quantum states in the continuous-variable regime.