bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial orientation of the facial nerve in relation to parotid tumours
Authors: Aird D W , Puttasiddaiah P , Berry S , Spyridakou C , Kumar M
Published: March 2006

Objective: The aim of this study was to identify the distribution of parotid tumours within the gland in relation to the facial nerve branches. Documentation revealing such a relationship has not been reported previously.

Method: A prospective study involving 111 patients was carried out over a period of 18 years in a specialist otolaryngology unit within a district general hospital. The relationship of the facial nerve to the tumour was graded into six types. The grading system was then employed to categorize each case.

Results: More than two-thirds of the tumours were pleomorphic adenomas. The majority of these were located in the body and not in the tail of the parotid gland. In 50 per cent of these cases, the tumour was in close association with the two major divisions of the facial nerve. In the case of Warthin's tumours, 47 per cent were located in the tail, below the lower division of the facial nerve.
Commercial watercress as an emerging source of fascioliasis in Northern France in 2002: results from an outbreak investigation
Authors: MAILLES A. , CAPEK I. , AJANA F. , SCHEPENS C. , ILEF D. , VAILLANT V.
Published: March 2006

In April 2002, five cases of fascioliasis were diagnosed in Tourcoing. A case-finding and a case-control study were carried out to identify the source of the outbreak and take appropriate control measures. Eighteen cases were identified through the medical laboratories carrying out serology for fascioliasis. Fourteen cases and 23 controls, identified by the physicians of the cases, were interviewed on symptoms of the disease and their consumption of uncooked plants. Cases were more likely than controls to have eaten commercialized raw watercress (OR 86·7, P<0·001) and 13 (93%) of the cases reported its consumption. A single producer common to all cases was identified. The inspection of his watercress beds showed a lack of protection against Lymnaea truncatula. This outbreak of fascioliasis due to commercialized watercress indicates that actual sanitary regulations do not allow for the efficient prevention of infestation of watercress production in France.
Molecular epidemiology of Norovirus strains circulating in Ireland from 2003 to 2004
Authors: WATERS A. , COUGHLAN S. , DUNFORD L. , HALL W. W.
Published: March 2006

Since 2002, the burden of norovirus (NoV) infection in Ireland has increased. Outbreaks in institutional settings are the most common causing widespread disruption to health service delivery. This is the first national study of NoV in the Republic of Ireland and its aim was to identify the major NoV strains circulating in Ireland over a 13-month period between November 2003 and November 2004, inclusive. A prospective study screened faecal samples (n=478) for NoV RNA. Positive samples (n=116) were further analysed by a second PCR, targeted to the orf1/orf2 junction of the virus. Phylogenetic analysis was based on sequence alignments of this domain. GII/4 viruses represented 92·2% of sequences, 2·7% were GII/2, GII/3 and GGIIB cluster-like strains. The remaining 5·2% were of GI origin. NoV was detectable throughout the study period, although two peaks of infection were observed. The majority of infections were caused by a range of closely related GII/4 NoV strains.
How safe is safer sex? High levels of HSV-1 and HSV-2 in female sex workers in London
Authors: FOX J. , TAYLOR G. P. , DAY S. , PARRY J. , WARD H.
Published: March 2006

Female sex workers in Europe have low levels of sexually transmitted infections, attributable to condom use. The aim of this paper is to describe the seroepidemiology of HSV-1 and HSV-2 in female sex workers in London by using a 15-year prospective study of 453 sex workers. The seroprevalence of HSV-1 was 74·4% and independently associated with birth in a ‘transitional country’ (OR 5·4, 95% CI 1·61–18·20). The seroprevalence of HSV-2 was 60% and declined over time; it was also independently associated with time in sex work (OR 2·12, 95% CI 1·23–3·65) and birth in a ‘developing country’ (OR 2·95, 95% CI 1·34–6·48). We show that a cohort of sex workers with extensive condom use and little known sexually transmitted infection have high levels of HSV-1 and HSV-2 infection, suggesting that condoms may not be universally protective. Sex workers are candidates for HSV vaccine efficacy or intervention studies.
THE STELA AS A CULTURAL SYMBOL IN CLASSIC AND CONTEMPORARY MAYA SOCIETIES
Authors: Christie Jessica Joyce
Published: March 2006

In Classic Maya society, the stela was an important medium through which historical information was conveyed. Stelae are free-standing stone slabs carved in low relief that usually depict portraits of rulers, which are accompanied by hieroglyphic texts recording the rulers' identity and actions. Recent research has focused on the stela not only as a carrier of information but also as an important cultural symbol in its own right. In 1985, Linda Schele and David Stuart proposed that the Classic Maya called the stela ate'-tun, orstone-tree. This identification led to the recognition of cultural continuities among the Highland Maya in Chiapas who, on occasion, substitute trees for individual crosses on their cross shrines. In 1996, Stuart suggested that the ancient Maya word for stela waslakamtun, orbig stone, emphasizing that the stela was an embodiment of the royal self in the sense that it shared some of the divine essence of the ruler. Drawing on epigraphic research, anthropological theory, the ethnographic literature, as well as personal field observations, I propose that certain spiritual and symbolic concepts of the stela continue to live in the crosses among the Maya today and that these concepts should be considered when we evaluate ancient contexts of meaning for the Maya stela.
SAAK'Y EL RETORNO DEL FIN DEL MUNDO: La plaga de langosta en las profecías del katun 13 Ahau
Authors: Quintanilla Alejandra García
Published: March 2006

Abstracto

Con base en dos textos “proféticos” para elkatun 13 Ahaucontenidos en elChilam Balam de Maníy en la concordancia hecha por Barrera Vásquez y Rendón para los textos paralelos que aparecen en el Chumayel, Kaua, y Maní, exploro símbolos, significados y saberes construídos por los mayas yucatecos respecto a uno de los más graves y recurrentes problemas de su historia: la plaga de langosta (Schistocerca piceifronspiceifrons). Los pronósticos van más allá del hambre y la enfermedad previsibles.Saak'aparece con el potencial destructivo suficiente para poner en crisis el ecosistema, la sociedad y hasta el orden cósmico. Los sabios que escribieron las profecías revelan un amplio conocimiento de la plaga, de los alcances de su impacto y, desde lo profundo de su cultura, hacen una propuesta para evitar que la crisis lleve a la ruptura social y a mayor sufrimiento y mortandad.
MESOAMERICA'S FORMATIVE SCHOLAR: GARETH W. LOWE, 1922–2004
Authors: Clark John E. , Pye Mary E. , Nelson Fred W.
Published: March 2006

The challenge in summing up the active life and productive career of any famous person is to put the important facts on record while steering a respectful path between hagiography and recitation of his curriculum vitae. We attempt to do this for our esteemed colleague and mentor, one of Mesoamerica's last originals, Gareth W. Lowe (Figure 1). With his death on March 8, 2004, in Tucson, Arizona, at age 82, Gareth left behind a legacy that reaches far beyond his well-deserved international reputation. Gareth spent 50 years of his life working in Mesoamerica, principally on the Formative period in Chiapas, Mexico. He first went to southern Mexico in 1953 as a crew member of the newly organized New World Archaeological Foundation (NWAF). Two years later, the NWAF was rescued by the sponsorship of the Church of Jesus Christ of Latter-Day Saints, and much later (in 1976) it became part of Brigham Young University. Gareth served two stints as NWAF field director (1956–1959, 1961–1975), basically as de facto director, and finally served officially as director from 1975 to 1987. In a real sense, Gareth was the NWAF, and its successes and agenda were largely his. The story of one cannot be understood without the other.
CLASSIC MAYA WARFARE AND WEAPONS: Spear, dart, and arrow points of Aguateca and Copan
Authors: Aoyama Kazuo
Published: March 2006

To provide some insights into the nature and role of warfare in the rise, development, and decline of Classic Maya civilization, this article discusses spear, dart, and arrow points used by the Classic Maya elites at the rapidly abandoned fortified city of Aguateca, Guatemala, and their temporal and spatial distribution patterns in and around Copan, Honduras. Both the royal family and elite scribes/artists at Aguateca used spear and dart points for intergroup human conflict as well as for artistic and craft production under enemy threat. An important implication is that the ruler and elite scribes/artists were also warriors. The unusually high concentrations of identifiable weaponry at the Early Classic hilltop center of Cerro de las Mesas as well as the Acropolis and other Late Classic locations in the Copan Valley, along with other lines of evidence, indicate that warfare was critical in the development and downfall of Classic Maya civilization at Copan.
Micrometastasis in lymph node
Authors: Masood S.
Published: March 2006

Determining whether cancer has spread to the lymph nodes is important in predicting survival from breast cancer and determining what treatment a patient requires. The traditional method of detecting such metastases, complete axillary node dissection, can result in lymphedema and other quality-of-life damaging side effects. The new technique of sentinel lymph node biopsy (SLNB) offers a way to test for lymph node metastases without causing the side effects of traditional axillary node dissection. Intraoperative analysis of SLNB is becoming an effective tool in assessment of the presence or absence of metastatic tumor, and therefore influences the treatment offered to the patient. Because of this central diagnostic use, as it is a new procedure, further studies need to be conducted to fully assess its role in breast cancer treatment.
Das Plasmazell-Myelom – von der molekularen Pathogenese zu neuen gezielten Therapien
Authors: Hess
Published: March 2006

Das Plasmazell-Myelom ist die zweithäufigste hämatologische Neoplasie. Die Zellen des malignen Klons weisen in vielen Fällen chromosomale Anomalien auf. Verschiedene dieser abnormalen Karyotypen ermöglichen eine Aussage über das Therapieansprechen und die Prognose. Myelomzellen zeigen oft abnormale Gen-Expressionen, besonders bei Onko-Genen und Tumorsuppressor-Genen. Das Gedeihen der Myelomzellen hängt in entscheidender Weise von einem engen Kontakt zu den Zellen des Knochenmarkstromas ab. Die Stromazellen sezernieren durch diese Zell-zu-Zell-Interaktion eine Reihe von Zytokinen. Über bekannte Signal-Kaskaden lösen diese in der Myelomzelle eine Reihe von Signalen aus, die Wachstum und Proliferation der Myelomzellen fördern und den programmierten Zelltod unterdrücken. Die Kenntnis dieser Signalpfade eröffnet zahlreiche neue Möglichkeiten für gezielte Therapien. Einige neue, gegen die wachstumsfördernden Zytokine gerichtete Moleküle sind in der frühen klinischen Erprobung. Substanzen, die den Kontakt zwischen der Myelomzelle und der Stromazelle stören, sind bereits verfügbar. Dazu gehören Thalidomid und dessen Analogon Lenalidomid sowie Bortezomib und Arsen-Trioxid. Das Leiden der Myelompatienten ist stark geprägt durch den Knochenbefall. Dort zeichnen sich ebenfalls neue therapeutische Konzepte ab. Mehrere Substanzen, welche die Differenzierung und Aktivierung der Osteoklasten unterdrücken, befinden sich in der klinischen Erprobung. Diese Stoffe könnten einen wesentlichen Beitrag zu einer besseren Lebensqualität der Myelompatienten leisten.
Public subsidies for water‐conserving irrigation investments: Hydrologic, agronomic, and economic assessment
Authors: Scheierling Susanne M. , Young Robert A. , Cardon Grant E.
Published: March 2006

Public subsidies for promoting the adoption of water‐conserving on‐farm irrigation technologies are frequently cited as means for making additional water available for higher‐valued uses in the water‐scarce western United States. On the basis of an agroeconomic model reflecting conditions in northeastern Colorado, hypothetical conservation subsidy policies are analyzed with regard to their effects on hydrologic and agronomic factors such as irrigation water delivery, consumptive use, and return flows, as well as on economic factors including crop mix, input use, irrigation technology choice, and agricultural net returns to water. The cost‐effectiveness of different subsidy arrangements for generating delivery reductions is also assessed, and implications for their implementation are derived. In contrast to assumptions underlying federal policies, the results confirm and extend earlier academic findings that subsidy policies are unlikely to provide real water conservation under many frequently encountered river basin conditions.
Two‐phase flow in rough‐walled fractures: Experiments and a flow structure model
Authors: Chen Chih‐Ying , Horne Roland N.
Published: March 2006

Despite some successful studies of two‐phase or unsaturated flows in ideal smooth‐walled fractures, the more realistic issues regarding fundamentals of two‐phase interactions in rough‐walled fractures are still poorly understood. In this study, we suggest a new approach to describe relative permeability behavior in rough‐walled fractures based on experimental observations of two‐phase flow structures. This approach lumps the microscale physical mechanism (viscous and capillary forces) into an apparent observable parameter, the channel tortuosity, which was found to dominate the reduction of the relative permeabilities from the values that would be expected based on the linear X curve (i.e., relative permeability equals saturation). Two analog fractures, the homogeneously rough‐walled and randomly rough‐walled fractures, combined with a smooth‐walled fracture investigated previously were studied to represent distinct surface geometry and heterogeneity. The uncertainty and quality of measured relative permeabilities in the fractures were discussed in the aspects of high‐resolution relative permeability and different averaging techniques. The experimental results from these three fractures could be described successfully by the proposed approach. Furthermore, we found that the magnitude of the channel tortuosity increases when the heterogeneity of the fracture surface increases. We also showed that the rates' (velocities) effects on flow structures within the experimental ranges were insignificant. Generalizing from channel tortuosities occurring in these three fractures, we were able to derive empirical, tortuous channel models. These models represent the current experimental data as well as observations from earlier studies with good agreement.
Superparamagnetic relaxation times for mixed anisotropy and high energy barriers with intermediate to high damping: 1. Uniaxial axis in a 〈001〉 direction
Authors: Newell Andrew J.
Published: March 2006

The Néel‐Brown theory for superparamagnetic relaxation rates is generalized to ferromagnetic particles with mixed cubic and uniaxial anisotropy. In this article the uniaxial axis is in a 〈001〉 crystallographic direction, while in part 2 it is in a 〈111〉 direction. The calculations are for high energy barriers, so transitions between states (stable equilibria) are rare. Transition rates from an energy minimum across a saddle point are determined by the height of the energy barrier and the shape of the energy surface around these two points. To account for multiple connections between minima, a master equation is solved for the probability distribution and the effect on the magnetic moment is calculated. Some relaxation modes have no effect on the moment. There are as many as five distinct relaxation rates for the probability distribution, but at most two for the moment. One rate is for the component parallel to the uniaxial axis, while the other is for the perpendicular component. These rates are functions of the cubic anisotropy parameterK′1and the uniaxial parameterKu. The double relaxation rate can give rise to phenomena such as partial superparamagnetism and multiple blocking temperatures.
Superparamagnetic relaxation times for mixed anisotropy and high energy barriers with intermediate to high damping: 2. Uniaxial axis in a 〈111〉 direction
Authors: Newell Andrew J.
Published: March 2006

Superparamagnetic relaxation rates are calculated for ferromagnetic particles with mixed cubic and uniaxial anisotropy. In part 1 the uniaxial axis is in a 〈001〉 crystallographic direction, while in this article it is in a 〈111〉 crystallographic direction. When Ku = 0, there are six remanent states but only one relaxation rate. As Ku increases, the remanent states converge on the uniaxial axis, merging with it at Ku = 0.76 K′1 for K′1 > 0 and at Ku = 0.22 ∣K′1∣ for K′1 < 0. In between the components parallel and perpendicular to the uniaxial axis relax at different rates. The rate for the perpendicular component increases with Ku. If all the remanent states have the same energy, there is a single, decreasing rate for the parallel component. However, for some values of Ku and K′1 there are two states with two different energies. There are then two rates, one decreasing and one increasing. For large Ku the remanence is uniaxial. In this article and part 1 the relaxation rates have an exponential and a prefactor. The prefactors are calculated in the high energy barrier, intermediate‐ to high‐damping approximation. For elongated particles the prefactor is smaller than predicted by the Néel‐Brown theory for uniaxial particles. The predicted relaxation rates are the same order of magnitude as experimental estimates for maghemite and magnetite. Better agreement cannot be expected because order‐of‐magnitude uncertainties still exist in both the experimental and theoretical estimates.
Variations in global thunderstorm activity inferred from the OTD records
Authors: Nickolaenko A. P. , Hayakawa M. , Sekiguchi M.
Published: March 2006

We use the data on the planetary distribution of thunderstorms collected by optical transient detector (OTD) to derive the properties of global electric activity. Processing of optical data indicates that modern observations from space confirm the general concept of thunderstorm distribution and motion. Close similarity is demonstrated between the World Meteorological Organization data and modern records including Carnegie curve. Departures noted might be caused by thunderstorms redistribution owing to climate change; the issue deserves a special examination.
Fast depletion of gaseous elemental mercury in the Kongsvegen Glacier snowpack in Svalbard
Authors: Fain Xavier , Ferrari Christophe P. , Gauchard Pierre‐Alexis , Magand Olivier , Boutron Claude
Published: March 2006

Gaseous elemental mercury (GEM, Hg°) was measured in the snowpack interstitial air on the Kongsvegen Glacier (Svalbard) between the surface and 190 cm depth. A rapid depletion of GEM from ∼5 to 0.4 ng.m−3 in the snowpack air was measured in less than 8 hours at a calculated depletion rate of ∼0.5–0.7 ng.m−3.h−1 while concentration of GEM above the snow stayed constant about 1.7 ng.m−3. This depletion could only be explained by chemical processes and this study suggests that Br. could be the most important reactant for the oxidation of GEM in the interstitial snow air. The lifetime of GEM was estimated to be ∼10 minutes with second order reaction rate constant between GEM and Br. of about ∼2 × 10−11 cm−3.molecule−1.s−1. These first experimental kinetic values for GEM oxidation in the snow air are in good agreement with both theoretical and modelling studies previously reported.
Link between isoprene and secondary organic aerosol (SOA): Pyruvic acid oxidation yields low volatility organic acids in clouds
Authors: Carlton Annmarie G. , Turpin Barbara J. , Lim Ho‐Jin , Altieri Katye E. , Seitzinger Sybil
Published: March 2006

Aqueous‐phase oxidation (in clouds and aerosols) is a potentially important source of organic aerosol and could explain the atmospheric presence of oxalic acid. Methylglyoxal, a water‐soluble product of isoprene, oxidizes further in the aqueous phase to pyruvic acid. Discrepancies in the literature regarding the aqueous‐phase oxidation of pyruvic acid create large uncertainties in the in‐cloud yields of secondary organic aerosol (SOA) and oxalic acid. Resolving the fate of aqueous‐phase pyruvic acid is critical to understanding SOA formation through cloud processing of water‐soluble products of isoprene, other alkenes and aromatics. In this work, aqueous‐phase photochemical reactions of pyruvic acid and hydrogen peroxide at pH values typical of clouds were conducted and demonstrated that photochemical oxidation of pyruvic acid yields glyoxylic, oxalic, acetic and formic acids. Oxalic and glyoxylic acids remain mostly in the particle phase upon droplet evaporation. Thus isoprene is an important precursor of in‐cloud SOA formation.
Influence of water fugacity and activation volume on the flow properties of fine‐grained anorthite aggregates
Authors: Rybacki E. , Gottschalk M. , Wirth R. , Dresen G.
Published: March 2006

To specify quantitatively the effect of pressure and water weakening on the flow strength of feldspar we performed triaxial creep experiments in a gas deformation apparatus at temperatures of 1000–1150°C, confining pressures of 100–450 MPa, and axial stresses of 10–400 MPa, resulting in strain rates of ∼6 × 10−7 to 3 × 10−3 s−1. Dense samples with a grain size of ∼3 μm were prepared by hot‐isostatic pressing of anorthite glass powder. Hydrous samples contain about 0.33 ± 0.14 wt % H2O and dry specimens 0.0005–0.02 wt % H2O. The estimated residual glass content of wet samples is <2 vol %. Samples deformed by grain boundary diffusion‐controlled creep at low stresses and dislocation creep at stresses ≳150 MPa. We estimate an activation volume of V ≈ 24 cm3mol−1 for anhydrous samples deforming in diffusion creep. For wet samples, deformed in hydrous conditions with varying buffers fixing oxygen fugacity, the activation volume is about 38 cm3 mol−1. Creep rate of hydrous anorthite aggregates depends on water fugacity raised to a power of r = 1.0 ± 0.3, suggesting hydrolysis of oxygen bonds. Considering the effect of activation volume and water fugacity on extrapolation of constitutive laws to conditions prevailing in the continental lower crust, viscosities of hydrous feldspar aggregates increase by a factor of <3.
Low‐degree mantle convection with strongly temperature‐ and depth‐dependent viscosity in a three‐dimensional spherical shell
Authors: Yoshida Masaki , Kageyama Akira
Published: March 2006

A series of numerical simulations of thermal convection of Boussinesq fluid with infinite Prandtl number, with Rayleigh number 107, and with the strongly temperature‐ and depth‐dependent viscosity in a three‐dimensional spherical shell is carried out to study the mantle convection of single‐plate terrestrial planets like Venus or Mars without an Earth‐like plate tectonics. The strongly temperature‐dependent viscosity (the viscosity contrast across the shell is ≥ 105) makes the convection under stagnant lid short‐wavelength structures. Numerous, cylindrical upwelling plumes are developed because of the secondary downwelling plumes arising from the bottom of lid. This convection pattern is inconsistent with that inferred from the geodesic observation of the Venus or Mars. Additional effect of the stratified viscosity at the upper/lower mantle (the viscosity contrast is varied from 30 to 300) are investigated. It is found that the combination of the strongly temperature‐ and depth‐dependent viscosity causes long‐wavelength structures of convection in which the spherical harmonic degree ℓ is dominant at 1–4. The geoid anomaly calculated by the simulated convections shows a long‐wavelength structure, which is compared with observations. The degree‐one (ℓ = 1) convection like the Martian mantle is realized in the wide range of viscosity contrast from 30 to 100 when the viscosity is continuously increased with depth at the lower mantle.
Effect of critical latitude and seasonal stratification on tidal current profiles along Ronne Ice Front, Antarctica
Authors: Makinson Keith , Schröder Michael , Østerhus Svein
Published: March 2006

The ice front region of Ronne Ice Shelf lies near the critical latitude of the semidiurnal M2 tide, the principal tidal constituent in the southern Weddell Sea. Here the Coriolis frequency almost equals the M2 tidal frequency, resulting in a strong dependence of the M2 tidal currents on depth and stratification and a boundary layer that can occupy the entire water column. Using data from four long‐term moorings along Ronne Ice Front, we confirm the presence of strongly depth‐dependent semidiurnal tidal currents and their sensitivity to changes in stratification. The time series show dramatic seasonal changes in tidal current profiles and significant interannual variability. During periods of stratification, the amplitude of the semidiurnal tides in the mid–water column shows a twofold increase and, despite being several kilometers offshore from the ice front, the tidal currents clearly show a second boundary layer originating from the adjacent ice shelf base. Together, these two boundary layers occupy most of the water column, up to 600 m deep, until intense sea ice formation and the production of High‐Salinity Shelf Water erodes the vertical stratification. During winter when homogeneous conditions prevail, a single bottom boundary layer occupies the entire water column at some locations. This strong seasonality and sensitivity of the M2 tidal current to stratification highlights the difficulties of interpreting current data from short‐term moorings while demonstrating that it is the best indicator for characterizing changes in stratification after direct observations of density variations.
Inverse estimation of Vcmax, leaf area index, and the Ball‐Berry parameter from carbon and energy fluxes
Authors: Wolf Adam , Akshalov Kanat , Saliendra Nicanor , Johnson Douglas A. , Laca Emilio A.
Published: March 2006

Canopy fluxes of CO2 and energy can be modeled with high fidelity using a small number of environmental variables and ecosystem parameters. Although these ecosystem parameters are critically important for modeling canopy fluxes, they typically are not measured with the same intensity as ecosystem fluxes. We developed an algorithm to estimate leaf area index (LAI), maximum carboxylation velocity (Vcmax), the Ball‐Berry parameter (m), and substrate‐dependent ecosystem respiration rate (βA) by inverting a commonly used modeling paradigm of canopy CO2 and energy fluxes. To test this algorithm, fluxes of sensible heat (H), latent heat (LE), and CO2 (Fc) were measured with eddy covariance techniques in a pristine grassland‐forb steppe site in northern Kazakhstan. We applied the algorithm to these data and identified ecosystem characteristics consistent with data across a time series of meteorological drivers from the Kazakhstan data. LAI was calculated by fitting the model to measured H + LE, Vcmax and βA were solved simultaneously by fitting the model to measured CO2 fluxes, and m was calculated by varying the partitioning of available energy between H and LE. Seasonal changes in LAI ranged from 2.0 to 2.4, Vcmax declined from 20 to 5 μmol CO2 m−2 s−1, respiration as a percentage of assimilation ranged from 0.5 to 0.75, and m varied from 17 to 24. Our results with the Kazakhstan data showed that LAI, Vcmax, ecosystem respiration, and m can be solved to accurately predict (R2 = 80 to 95%) carbon and energy fluxes with nonsignificant bias at 20‐min and daily timescales. The ecosystem characteristics calculated in our study were consistent with independent measurements of the seasonal dynamics of a shortgrass steppe in Kazakhstan and with values published in the literature. These characteristics were closely linked to mean daily fluxes of CO2 but were not dependent on the environmental drivers for the periods they were measured. We conclude that process model inversion has potential for comparing CO2 and energy fluxes among different ecosystems and years and for providing important ecosystem parameters for evaluating climatic influences on CO2 and energy fluxes.
Minimum and maximum propagation frequencies for internal gravity waves
Authors: Jones R. Michael
Published: March 2006

Estimates of the effects of vorticity, baroclinicity, and rate of strain on the minimum and maximum propagation frequencies of gravity waves are given using a general dispersion relation for internal waves in the atmosphere and ocean. Rotating the coordinate axes to eliminate from the dispersion relation cross terms in the wavenumber makes it much easier to determine the minimum and maximum frequencies for which gravity waves can propagate. Corrections to the minimum frequency from breakdown of the WKB approximation are included.
Aircraft vertical profiles of trace gas and aerosol pollution over the mid‐Atlantic United States: Statistics and meteorological cluster analysis
Authors: Taubman B. F. , Hains J. C. , Thompson A. M. , Marufu L. T. , Doddridge B. G. , Stehr J. W. , Piety C. A. , Dickerson R. R.
Published: March 2006

From 1997 to 2003, airborne measurements of O3, CO, SO2, and aerosol properties were made during summertime air pollution episodes over the mid‐Atlantic United States (34.7–44.6°N, 68.4–81.6°W) as part of the Regional Atmospheric Measurement, Modeling, and Prediction Program (RAMMPP). Little diurnal variation was identified in the CO, SO2, and Ångström exponent profiles, although the Ångström exponent profiles decreased with altitude. Boundary layer O3 was greater in the afternoon, while lower free tropospheric O3 was invariant at ∼55 ppbv. The single scattering albedo increased from morning to afternoon (0.93 ± 0.01–0.94 ± 0.01); however, both profiles decreased with altitude. A cluster analysis of back trajectories in conjunction with the vertical profile data was used to identify source regions and characteristic transport patterns during summertime pollution episodes. When the greatest trajectory density lay over the northern Ohio River Valley, the result was large O3 values, large SO2/CO ratios, highly scattering particles, and large aerosol optical depths. Maximum trajectory density over the southern Ohio River Valley resulted in little pollution. The greatest afternoon O3 values occurred during periods of stagnation. North‐northwesterly and northerly flow brought the least pollution overall. The contribution of regional transport to afternoon boundary layer O3 was quantified. When the greatest cluster trajectory density lay over the Ohio River Valley (∼59% of the profiles), transport accounted for 69–82% of the afternoon boundary layer O3. Under stagnant conditions (∼27% of the profiles), transport only accounted for 58% of the afternoon boundary layer O3. The results from this study provide a description of regional chemical and transport processes that will be valuable to investigators from the Baltimore, New York, and Pittsburgh EPA Supersites.
Chaotic solute advection by unsteady groundwater flow
Authors: Sposito Garrison
Published: March 2006

Solute mixing in fluids is enhanced significantly by chaotic advection, the phenomenon in which fluid pathlines completely fill the spatial domain explored by a laminar flow. Steady groundwater flows are, in general, not well conditioned for this phenomenon because Darcy's law confines them spatially to nonintersecting stream surfaces. Unsteady groundwater flows, however, may, in principle, induce chaotic solute advection if their time dependence is periodic and produces frequent reorientation of pathlines, an effect connected closely to the development of high solute mixing efficiencies. In this paper, a simple, two‐dimensional model groundwater system is studied theoretically to evaluate the possibility of inducing chaotic solute advection in the flow field near a recirculation well whose pumping behavior is time periodic. In the vernacular of dynamical systems theory the model studied is an example of a Hamiltonian system, thus allowing a mathematical formulation that facilitates consideration of whether chaotic advection can occur. When the model system is driven time periodically by alternate operation of the production and injection components of the recirculation well, numerical simulations of the fluid pathlines indicate that regions of chaotic solute advection will, indeed, develop in the flow field near the well, with expected major improvement in plume spreading.
Spatial patterns of ground heat gain in the Northern Hemisphere
Authors: Beltrami Hugo , Bourlon Evelise , Kellman Lisa , González‐Rouco J. F.
Published: March 2006

Variations in the Earth's surface energy balance are recorded in the subsurface as perturbations of the steady state thermal field. Here we invert 558 temperature‐depth profiles in the Northern Hemisphere (NH), in order to estimate the energy balance history at the continental surface from heat flux anomalies in the subsurface. The heat gain is spatially variable and does not appear to have been persistent for the last 200 years at all locations, but overall continental areas have absorbed energy in the last 50 years. Results indicate a mean surface heat flux of 20.6 mWm−2 over the last 200 years. The total heat absorbed by the ground is 4.8 × 1021J and 13.3 × 1021J for the last 50 and 200 years respectively. We suggest that our results may be useful for state‐of‐the‐art General Circulation Model (GCM) validation and for land‐surface coupling schemes.
Pollutant lead reveals the pre‐Hellenistic occupation and ancient growth of Alexandria, Egypt
Authors: Véron A. , Goiran J. P. , Morhange C. , Marriner N. , Empereur J. Y.
Published: March 2006

It is generally accepted that Alexandria ad Aegyptum was founded ex nihilo in 331 BC by Alexander the Great, rapidly growing into one of antiquity's most opulent economic and intellectual centers. However, ancient texts by Strabo (17.1.6) and Pliny (NH 5.11.62) suggest the existence of a pre‐Hellenistic settlement named Rhakotis. This literary evidence has fuelled contentious scholarly debate for decades. Here we present new geochemical data from Alexandria's ancient bay sediments, elucidating unequivocal proof for pollutant lead (Pb) input into the harbor during the Egyptian Old Kingdom (2686–2181 BC). A second contamination peak is detected during the Iron Age (1000–800 BC), at the end of the prosperous Ramesses reigns. These findings evidence thriving pre‐Hellenistic settlements in Alexandria. During the Greek and Roman periods, we expound the largest Pb pollution ever encountered in ancient city sediments with Pb levels twice as high as those measured in contemporary industrialized estuaries.
Activation of Calcium/Calmodulin-Dependent Protein Kinases after Traumatic Brain Injury
Authors: Atkins Coleen M , Chen Shaoyi , Alonso Ofelia F , Dietrich W Dalton , Hu Bing-Ren
Published: March 2006

A prominent cognitive impairment after traumatic brain injury (TBI) is hippocampal-dependent memory loss. Although the histopathologic changes in the brain are well documented after TBI, the underlying biochemical mechanisms that contribute to memory loss have yet to be thoroughly delineated. Thus, we determined if calcium/calmodulin-dependent protein kinases (CaMKs), known to be necessary for the formation of hippocampal-dependent memories, are regulated after TBI. Sprague—Dawley rats underwent moderate parasagittal fluid-percussion brain injury on the right side of the parietal cortex. The ipsilateral hippocampus and parietal cortex were Western blotted for phosphorylated, activated α-calcium/calmodulin-dependent protein kinase II (α-CaMKII), CaMKIV, and CaMKI. α-Calcium/calmodulin-dependent protein kinase II was activated in membrane subcellular fractions from the hippocampus and parietal cortex 30 mins after TBI. CaMKI and CaMKIV were activated in a more delayed manner, increasing in phosphorylation 1 h after TBI. The increase in activated α-CaMKII in membrane fractions was accompanied by a decrease in cytosolic total α-CaMKII, suggesting redistribution to the membrane. Using confocal microscopy, we observed that α-CaMKII was activated within hippocampal neurons of the dentate gyrus, CA3, and CA1 regions. Two downstream substrates of α-CaMKII, the AMPA-type glutamate receptor GluR1, and cytoplasmic polyadenylation element-binding protein, concomitantly increased in phosphorylation in the hippocampus and cortex 1 h after TBI. These results demonstrate that several of the biochemical cascades that subserve memory formation are activated unselectively in neurons after TBI. As memory formation requires activation of CaMKII signaling pathways at specific neuronal synapses, unselective activation of CaMKII signaling in all synapses may disrupt the machinery for memory formation, resulting in memory loss after TBI.
Promoter Region Methylation and Reduced Expression of Thrombospondin-1 after Oxygen—Glucose Deprivation in Murine Cerebral Endothelial Cells
Authors: Hu Chaur-Jong , Chen Shang-Der , Yang Ding-I , Lin Teng-Nan , Chen Chuan-Mu , Huang Tim Hui-Ming , Hsu Chung Y
Published: March 2006

Angiogenesis is induced in response to ischemia. Thrombospondin-1 (TSP-1) is a potent angiostatic factor. Silencing of TSP-1 expression may contribute to the postischemic angiogenesis. Upregulation of TSP-1, in contrast, may terminate the postischemic angiogenesis. A possible mechanism that silences TSP-1 expression is the DNA methylation of its promoter region. DNA methylation has been reported following cerebral ischemia. The present study aimed to explore whether methylation of the promoter region of TSP-1 regulates its expression after oxygen—glucose deprivation (OGD) in murine cerebral endothelial cells (CECs) in vitro. Sublethal OGD increased the extent of methylation of the promoter region of TSP-1 with a concurrent decrease in TSP-1 mRNA and protein expression in CECs. After reoxygenation, demethylation of the TSP-1 promoter region led to the restoration of TSP-1 mRNA and protein expression. The extent of methylation of the promoter region of TSP-1 was inversely correlated with the extent of TSP-1 gene expression at mRNA and protein levels after OGD. Oxygen—glucose deprivation-induced reduction in the TSP-1 mRNA level was not accompanied by a change in mRNA stability. These findings raise the possibility that OGD downregulation of TSP-1 expression is at least in part due to methylation of its promoter region.
Ca2+ release triggered by NAADP in hepatocyte microsomes
Authors: Mándi Miklós , Tóth Balázs , Timár György , Bak Judit
Published: March 2006

NAADP (nicotinic acid–adenine dinucleotide phosphate) is fast emerging as a new intracellular Ca2+-mobilizing messenger. NAADP induces Ca2+ release by a mechanism that is distinct from IP3 (inositol 1,4,5-trisphosphate)- and cADPR (cADP-ribose)-induced Ca2+ release. In the present study, we demonstrated that micromolar concentrations of NAADP trigger Ca2+ release from rat hepatocyte microsomes. Cross-desensitization to IP3 and cADPR by NAADP did not occur in liver microsomes. We report that non-activating concentrations of NAADP can fully inactivate the NAADP-sensitive Ca2+-release mechanism in hepatocyte microsomes. The ability of thapsigargin to block the NAADP-sensitive Ca2+ release is not observed in sea-urchin eggs or in intact mammalian cells. In contrast with the Ca2+ release induced by IP3 and cADPR, the Ca2+ release induced by NAADP was completely independent of the free extravesicular Ca2+ concentration and pH (in the range 6.4–7.8). The NAADP-elicited Ca2+ release cannot be blocked by the inhibitors of the IP3 receptors and the ryanodine receptor. On the other hand, verapamil and diltiazem do inhibit the NAADP- (but not IP3- or cADPR-) induced Ca2+ release.
Myosin heavy-chain kinase A from Dictyostelium possesses a novel actin-binding domain that cross-links actin filaments
Authors: Russ Misty , Croft Daniel , Ali Omar , Martinez Raquel , Steimle Paul A.
Published: March 2006

Myosin heavy-chain kinase A (MHCK A) catalyses the disassembly of myosin II filaments in Dictyostelium cells via myosin II heavy-chain phosphorylation. MHCK A possesses a ‘coiled-coil’-enriched domain that mediates the oligomerization, cellular localization and actin-binding activities of the kinase. F-actin (filamentous actin) binding by the coiled-coil domain leads to a 40-fold increase in MHCK A activity. In the present study we examined the actin-binding characteristics of the coiled-coil domain as a means of identifying mechanisms by which MHCK A-mediated disassembly of myosin II filaments can be regulated in the cell. Co-sedimentation assays revealed that the coiled-coil domain of MHCK A binds co-operatively to F-actin with an apparent KD of approx. 0.5 μM and a stoichiometry of approx. 5:1 [actin/C(1–498)]. Further analyses indicate that the coiled-coil domain binds along the length of the actin filament and possesses at least two actin-binding regions. Quite surprisingly, we found that the coiled-coil domain cross-links actin filaments into bundles, indicating that MHCK A can affect the cytoskeleton in two important ways: (1) by driving myosin II-filament disassembly via myosin II heavy-chain phosphorylation, and (2) by cross-linking/bundling actin filaments. This discovery, along with other supporting data, suggests a model in which MHCK A-mediated bundling of actin filaments plays a central role in the recruitment and activation of the kinase at specific sites in the cell. Ultimately this provides a means for achieving the robust and highly localized disruption of myosin II filaments that facilitates polarized changes in cell shape during processes such as chemotaxis, cytokinesis and multicellular development.
Mode of action and subsite studies of the guluronan block-forming mannuronan C-5 epimerases AlgE1 and AlgE6
Authors: Holtan Synnøve , Bruheim Per , Skjåk-Bræk Gudmund
Published: March 2006

AlgE1, AlgE5 and AlgE6 are members of a family of mannuronan C-5 epimerases encoded by the bacterium Azotobacter vinelandii, and are active in the biosynthesis of alginate, where they catalyse the post-polymerization conversion of β-D-mannuronic acid (M) residues into α-L-guluronic acid residues (G). All enzymes show preference for introducing G-residues neighbouring a pre-existing G. They also have the capacity to convert single M residues flanked by G, thus ‘condensing’ G-blocks to form almost homopolymeric guluronan. Analysis of the length and distribution of G-blocks based on specific enzyme degradation combined with size-exclusion chromatography, electrospray ionization MS, HPAEC–PAD (high-performance anion-exchange chromatography and pulsed amperometric detection), MALDI (matrix-assisted laser-desorption ionization)-MS and NMR revealed large differences in block length and distribution generated by AlgE1 and AlgE6, probably reflecting their different degree of processivity. When acting on polyMG as substrates, AlgE1 initially forms only long homopolymeric G-blocks >50, while AlgE6 gives shorter blocks with a broader block size distribution. Analyses of the AlgE1 and AlgE6 subsite specificities by the same methodology showed that a mannuronan octamer and heptamer respectively were the minimum substrate chain lengths needed to accommodate enzyme activities. The fourth M residue from the non-reducing end is epimerized first by both enzymes. When acting on MG-oligomers, AlgE1 needed a decamer while AlgE6 an octamer to accommodate activity. By performing FIA (flow injection analysis)-MS on the lyase digests of epimerized and standard MG-oligomers, the M residue in position 5 from the non-reducing end was preferentially attacked by both enzymes, creating an MGMGGG-sequence (underlined and boldface indicate the epimerized residue).
Finite quantum kinematics of the harmonic oscillator
Authors: Shiri-Garakani Mohsen , Finkelstein David Ritz
Published: March 2006

Arbitrarily small changes in the commutation relations suffice to transform the usual singular quantum theories into regular quantum theories. This process is an extension of canonical quantization that we call general quantization. Here we apply general quantization to the time-independent linear harmonic oscillator. The unstable Heisenberg group becomes the stable group SO(3). This freezes out the zero-point energy of very soft or very hard oscillators, like those responsible for the infrared or ultraviolet divergencies of usual field theories, without much changing the medium oscillators. It produces pronounced violations of equipartition and of the usual uncertainty relations for soft or hard oscillators, and interactions between the previously uncoupled excitation quanta of the oscillator, weakly attractive for medium quanta, strongly repulsive for soft or hard quanta.
One-particle and few-particle billiards
Authors: Lansel Steven , Porter Mason A. , Bunimovich Leonid A.
Published: March 2006

We study the dynamics of one-particle and few-particle billiard systems in containers of various shapes. In few-particle systems, the particles collide elastically both against the boundary and against each other. In the one-particle case, we investigate the formation and destruction of resonance islands in (generalized) mushroom billiards, which are a recently discovered class of Hamiltonian systems with mixed regular-chaotic dynamics. In the few-particle case, we compare the dynamics in container geometries whose counterpart one-particle billiards are integrable, chaotic, and mixed. One of our findings is that two-, three-, and four-particle billiards confined to containers with integrable one-particle counterparts inherit some integrals of motion and exhibit a regular partition of phase space into ergodic components of positive measure. Therefore, the shape of a container matters not only for noninteracting particles but also for interacting particles.
Impact of the laser wavelength on the dynamics of Xe cluster plasma produced by an intense ultrashort laser pulse
Authors: Petrov G. M. , Davis J.
Published: March 2006

The dynamics of Xe clusters irradiated by a high intensity subpicosecond laser pulse is investigated through a relativistic time-dependent three-dimensional particle simulation model. In order to explore the effect of transition from underdense to overdense plasma, we performed calculations for laser wavelengths between 100 and 800 nm. The ionization of clusters and charge accumulation was found to be independent of the laser wavelength, while the removal rate of electrons from the cluster into the intercluster space, mean electron and ion energies, and energy absorption increase with the wavelength.
From Stäckel systems to integrable hierarchies of PDE’s: Benenti class of separation relations
Authors: Błaszak Maciej , Marciniak Krzysztof
Published: March 2006

We propose a general scheme of constructing of soliton hierarchies from finite dimensional Stäckel systems and related separation relations. In particular, we concentrate on the simplest class of separation relations, called Benenti class, i.e., certain Stäckel systems with quadratic in momenta integrals of motion.
Controlling chaotic robots with kinematical redundancy
Authors: Li Li , Liu Zhaohui , Zhang Dengcai , Zhang H.
Published: March 2006

Robots with kinematical redundancy under the pseudoinverse control exhibit undesirable chaotic joint motion, which leads to erratic behaviors. In this study, we used the delayed feedback method to control chaotic motions of a planar 3R rigid and a planar 3R flexible redundant robot under the pseudoinverse control when the end-effector traces a closed-path repeatedly in the work space. It was demonstrated that chaotic motions of robots with kinematical redundancy can be turned into regular motion when the delayed feedback method was applied with some appropriate parameters. This study provides a new insight helpful to solve the repeatability problem of redundant manipulators.