bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of motility, acrosomal integrity, and viability of giant panda (Ailuropoda melanoleuca) sperm following short‐term storage at 4°C
Authors: Olson Mary Ann , Yan Huang , DeSheng Li , Spindler Rebecca , Howard JoGayle , Hemin Zhang , Durrant Barbara
Published: December 2003

Short‐term cool storage of semen affords many of the same benefits as cryopreservation, without the extensive cryoinjury to sperm associated with freezing. Semen storage for artificial insemination (AI) is an integral part of giant panda captive breeding programs. AI functions to generate offspring from males that have never bred, are underrepresented, or are unable to breed with genetically desirable females due to geographic separation. In the present study, semen was collected by electroejaculation from six giant pandas and extended in four media (TEST with 0% or 5% glycerol, or SFS with 0% or 5% glycerol). Subsequently, initial motility (MOT), speed of progression (SOP), percent live (% L), and percent normal acrosome (% NAR) values were recorded. These parameters were assessed again at 4, 8, 24, and 48 hr of incubation at 4°C in each medium. Motility scores (MS) were calculated as MOT×SOP2. The MS of each sample was also recorded after the addition of 20 mM caffeine. Results were expressed as a percent of the initial value (% I). Although all three parameters decreased over time, the MS decreased at a faster rate than either the % L or the % NAR. There were significant differences between individual pandas for each measured parameter, while only % IMS was significantly affected by medium (P=.0006). The addition of caffeine increased % IMS at all time periods and reduced the differences between media to nonsignificant levels. The addition of glycerol was not beneficial for short‐term semen storage. These data indicate that storage of giant panda semen at 4°C for up to 48 hr maintains sperm viability at a level sufficient for use in an AI program. Zoo Biol 22:529–544, 2003. © 2003 Wiley‐Liss, Inc.
Effect of felid activity on zoo visitor interest
Authors: Margulis Susan W. , Hoyos Catalina , Anderson Meegan
Published: December 2003

The extent to which the presence of zoo visitors influences animal behavior, and the ways in which animal activity influences visitor interest and perception, are of great interest to zoological parks. Visitors have been variously characterized as being enriching for zoo animals, as being stressors, and generally as influencing behavior in measurable ways. Most studies have focused on primates, and have assumed a “visitor effect” paradigm (i.e., visitors influence animal behavior). Here we present findings from a study of a nonprimate group (felids), and examine the “visitor attraction” model, which assumes that visitors are attracted to active animals. We assessed visitor interest and number at seven cat exhibits at the Brookfield Zoo during the spring and summer of 2002. Data were collected during 1‐min scans of each exhibit at 10‐min intervals. The results indicate that visitor presence per se did not influence cat activity, and that visitor interest was generally greater when cats were active. Various species differences may be explained by visitor familiarity with the species, variations in exhibit design, and species‐specific activity budgets. We conclude that the visitor attraction model may be more appropriate for taxa, such as large cats, that tend naturally to be largely inactive and to respond little (if at all) to visitor disturbances or efforts to engage. The relationship must be viewed as bidirectional: visitors influence animal behavior, and animal behavior influences visitor interest. However, the strength and primary direction of this relationship is likely taxon‐specific. We suggest that a visitor attraction model may be more appropriate not only for felids, but for other taxa with similar behavioral patterns and responses as well. Zoo Biol 22:587–599, 2003. © 2003 Wiley‐Liss, Inc.
Dangerous animals in captivity: Ex situ tiger conflict and implications for private ownership of exotic animals
Authors: Nyhus P.J. , Tilson R.L. , Tomlinson J.L.
Published: December 2003

The risks associated with tiger attacks on people in the wild are well documented. There may currently be more tigers in captivity than in the wild, but relatively little is known about the risks of injury or death associated with owning and managing captive tigers and other large carnivores. The purpose of this study was to conduct a global assessment of attacks by captive tigers on people, with particular emphasis on cases in the United States. Our analysis of 30 international media sources and additional documents uncovered 59 unique incidents in 1998–2001 in which people were reportedly injured or killed by captive tigers. In the United States, seven people were reportedly killed and at least 27 were injured—a rate of 1.75 fatal attacks and at least nine nonfatal attacks per year. All but one fatal attack in the United States occurred in situations where tigers were privately owned or held in private facilities. Forty‐two percent of the victims were classified as visitors, and almost one‐quarter of the victims were under the age of 20. These results suggest that the victims underestimated the dangers posed by direct contact with these animals. In this work we review current legislation regarding captive ownership of tigers and other large exotic animals, and contradict claims by those who support private ownership of tigers and other large felids that the risks associated with owning and viewing these animals are insignificant. We conclude that the growing number of people who own tigers and other large exotic animals is cause for concern because of the danger to the animals, the handlers, and the public. The problem of private ownership of dangerous exotic animals has broad implications for tiger and large‐carnivore conservation, public health, and animal welfare. We support the regulation of private ownership of dangerous exotic animals, and encourage scientific analysis of this contentious issue. Zoo Biol 22:573–586, 2003. © 2003 Wiley‐Liss, Inc.
Hueidea (Fuscideaceae), a new lichen genus from alpine Australia
Authors: Kantvilas Gintaras , McCarthy Patrick M.
Published: December 2003

Hueidea australiensis Kantvilas & P.M. McCarthy gen. et sp. nov. (Fuscideaceae) is described from seasonally inundated, granite rocks in the Mt Kosciuszko area of New South Wales, Australia. The genus is characterized by the crustose habit, a green unicellular photobiont of the type found in the Fuscideaceae, Teloschistes-type, eight-spored asci, non-adhering, simple paraphyses and polarilocular, hyaline ascospores. Its systematic position is discussed, based on a comparative study of a range of related or superficially similar taxa from the Teloschistaceae and Fuscideaceae.
The interaction between E‐tropomodulin and thymosin β‐10 rescues tumor cells from thymosin β‐10 mediated apoptosis by restoring actin architecture
Authors: Rho Seung Bae , Chun Taehoon , Lee Seung-Hoon , Park Kyoungsook , Lee Je-Ho
Published: December 2003

Thymosin β‐10 (TB10) is a small G‐actin binding protein that induces depolymerization of intracellular F‐actin pools by sequestering actin monomers. Previously, we demonstrated that overexpression of TB10 in ovarian tumor cells increased the rate of cell death. As an initial step to define molecular mechanism of TB10‐dependent apoptotic process in ovarian tumor cells, we searched a human ovary cDNA library for a novel TB10 binding protein using a yeast two‐hybrid system. The selected protein was human E‐tropomodulin (E‐Tmod), another component of the actin binding proteins. Subsequently, two interacting protein components were determined quantitatively. Results showed that the full‐length TB10 is required to bind with E‐Tmod, and the TB10 binding site on E‐Tmod partially overlaps with the actin binding site on E‐Tmod. Moreover, introduction of E‐Tmod cDNA into a tumor cell line reversed TB10 mediated apoptosis and restored actin architectures. These results may suggest that TB10 regulates apoptotic homeostasis by not only just binding to actin but also competing or blocking the protein complex formation of E‐Tmod with actin.
Hepatitis B virus X protein modulates peroxisome proliferator‐activated receptor γ through protein–protein interaction
Authors: Choi Youn-Hee , Kim Ha-il , Seong Je Kyung , Yu Dae-Yeul , Cho Hyeseong , Lee Mi-Ock , Lee Jae Myun , Ahn Yong-ho , Kim Se Jong , Park Jeon Han
Published: December 2003

Ligand activation of peroxisome proliferator‐activated receptor γ (PPARγ) has been reported to induce growth inhibition and apoptosis in various cancers including hepatocellular carcinoma (HCC). However, the effect of hepatitis B virus X protein (HBx) on PPARγ activation has not been characterized in hepatitis B virus (HBV)‐associated HCC. Herein, we demonstrated that HBx counteracted growth inhibition caused by PPARγ ligand in HBx‐associated HCC cells. We found that HBx bound to DNA binding domain of PPARγ and HBx/PPARγ interaction blocked nuclear localization and binding to recognition site of PPARγ. HBx significantly suppressed a PPARγ‐mediated transactivation. These results suggest that HBx modulates PPARγ function through protein–protein interaction.
CRP2 is an autonomous actin‐binding protein
Authors: Grubinger Markus , Gimona Mario
Published: December 2003

Cysteine‐rich proteins (CRPs) have been shown to be involved in cell differentiation, transcriptional regulation and the organisation of the actin cytoskeleton. Thus far, the latter function has been inferred solely from the in vitro interaction of CRP1, CRP2, and CRP3 with α‐actinin and zyxin. We show here that purified, recombinant CRP2 binds directly to F‐actin in vitro in co‐sedimentation assays. Using a green fluorescent protein (GFP)‐tagged construct of CRP2 we analysed its localisation and dynamics in A7r5 rat smooth muscle cells. CRP2 was associated with the actin cytoskeleton and decorated actin stress fibres in a continuous fashion, unlike the periodic labelling pattern observed for α‐actinin and zyxin, which also accumulate in focal adhesions. Using live video fluorescence microscopy we observed the behaviour of GFP‐CRP2 during the dynamic rearrangement of the actin cytoskeleton in phorbol 12,13‐dibutyrate‐treated A7r5 cells. In contrast to the actin‐binding proteins SM22α and α‐actinin, GFP‐CRP2 did not translocate into the podosomes induced by this treatment, but remained preferentially bound to the stress fibres, suggesting an actin filament‐stabilising role for CRP2. When fused to the mitochondrial targeting sequence from the Listeria protein ActA, GFP‐CRP2 was almost completely localised to mitochondria, but no significant recruitment of either α‐actinin or zyxin could be observed. Taken together, our results demonstrate that CRP2 can bind to F‐actin directly and that the association with the actin cytoskeleton is independent of α‐actinin or zyxin localisation in the cell, thus questioning the role of CRP2 as a regulator of α‐actinin function in vivo.
The contribution of serine residues 1588 and 1755 to phosphorylation of the type I inositol 1,4,5‐trisphosphate receptor by PKA and PKG
Authors: Soulsby Matthew D , Alzayady Kamil , Xu Qun , Wojcikiewicz Richard J.H
Published: December 2003

Type I inositol 1,4,5‐trisphosphate receptors can be phosphorylated by cAMP‐dependent protein kinase (PKA) and cGMP‐dependent protein kinase (PKG). To define the site‐specificity of these events we analyzed the phosphorylation of mutant receptors expressed in intact cells. These studies showed that S1588 and S1755, the serine residues within kinase consensus sequences, are equally sensitive to PKA, that phosphorylation events at these sites are independent of each other, and that PKG predominantly phosphorylates S1588. These findings provide the basis for understanding the functional consequences of type I inositol 1,4,5‐trisphosphate receptor phosphorylation.
Enhancement of RNAi activity by improved siRNA duplexes
Authors: Hohjoh Hirohiko
Published: December 2003

RNA interference (RNAi) is a powerful tool for suppressing the expression of a gene of interest, in which 21–25 nucleotide short interfering RNA (siRNA) duplexes homologous to the silenced gene function as sequence‐specific RNAi mediators. The present study shows that newly designed siRNA duplexes, ‘fork‐siRNA duplexes’, whose sense‐stranded siRNA elements carry one to four nucleotide mismatches at the 3′‐ends against the antisense‐stranded siRNA elements, can enhance RNAi activity over conventional siRNA duplexes in cultured mammalian cells.
Hafellia alisioae and H. gomerana (lichenized Ascomycetes, Physciaceae), two new species from the Canary Islands, with a key to all known corticolous species
Authors: Etayo Javier , Marbach Bernhard
Published: December 2003

Two new corticolous species, Hafellia alisioae and H. gomerana (lichenized Ascomycetes, Physciaceae), collected from twigs of coastal shrubs on the Canary Islands are described. The new species are discussed in relation to other Hafellia species with similar characters. An overview and a key for 23 corticolous species of Hafellia with 2-celled ascospores is provided.
Ochrolechia Splendens (Pertusariaceae), a new species from south-western North America
Authors: Lumbsch H. Thorsten , Messuti María Inés , Nash Thomas H.
Published: December 2003

The new species Ochrolechia splendens Lumbsch and Messuti, is described from Mexico, south-western North America, where it occurs on exposed siliceous rocks. It is characterized by relatively large apothecia with entire margins, the presence of the gyrophoric acid chemosyndrome in the thallus and apothecial disc and the presence of lichexanthone as major components.
Organic matter in river‐influenced continental margin sediments: The land‐ocean and climate linkage at the Late Quaternary Congo fan (ODP Site 1075)
Authors: Holtvoeth Jens , Wagner Thomas , Schubert Carsten J.
Published: December 2003

Late Quaternary sections (1.2 Ma) of ODP‐Site 1075 from the Congo deep‐sea fan are investigated to reconstruct variations of terrigenous organic matter supply to the eastern equatorial Atlantic. To characterize the organic matter (OM) with regard to marine and terrigenous amounts we used elemental analysis (C, N, S), stable carbon isotopes (bulk δ13Corg), Rock‐Eval pyrolysis, and terrigenous biomarkers (lignin phenols from CuO oxidation). The records of total organic carbon (TOC) contents, Corg/Ntot ratios, bulk OM degradation rates (Corg/Corg*), and the ratios of hydrocarbons (HC) from low‐mature versus HC from high‐mature OM (lm/hm) reveal pronounced cyclic changes in OM abundance, preservation, and reactivity that are closely related to the precessional controlled record of insolation, and thus, to variations in upwelling intensity and fluvial run‐off. Primary productivity off the Congo is stimulated by both, enhanced nutrient supply in response to trade‐induced upwelling during arid African climates (insolation minima) and fluvial nutrient delivery during humid stages (following insolation maxima), especially due to the contribution of dissolved silica that is taken up preferably by diatoms. However, results stemming from a multiparameter approach reveal that the fluvial supply of degraded OM and black carbon (BC) associated with fine‐grained sediments from soil erosion is a decisive factor for the preservation of marine OM and, in addition, significantly influences the geochemical signature of bulk and terrigenous OM. Riverine and eolian supply of C4 plant matter, as well as enhanced concentrations of BC, during arid and arid‐to‐humid transitional climate stages, may lead to a severe underestimation of terrigenous organic carbon, if its amount is calculated from bulk isotopic ratios using binary end‐member models. During the humid stages, it is the massive supply of 13C‐enriched soil OM with low Corg/Ntot ratios that may suggest a mainly marine composition of bulk OM. In fact, terrigenous OM governs bulk OM geochemical signatures in the sediments of the Congo deep‐sea fan, a result that is contradictory to earlier studies, especially to the conventional interpretation of the bulk δ13Corg signal.
Role of heterogeneity in elastic properties and layer thickness in the jointing of layered sedimentary rocks
Authors: Renshaw Carl E. , Myse Todd A. , Brown Stephen R.
Published: December 2003

We investigate how overburden weight acts in conjunction with heterogeneity in elastic properties between sedimentary layers to induce the tensile stress necessary for regional jointing. Model results are supported by data from a new experimental design in which an aluminum loading frame sandwiches a tabular specimen of brittle material of varying thickness between two layers of rubber. Load is applied perpendicular to the layering. The aluminum load frame only permits the rubber layers to expand in one direction, leading to the formation of a system of parallel fractures in the brittle layer as the rubber extends uniaxially. The initiation of the first fractures is independent of the layer thickness. As fracture spacing decreases below the layer thickness, mechanical interaction between closely‐spaced fractures limits the initiation of additional fractures. The onset of mechanical inhibition of additional fracture growth occurs at greater normalized fracture spacings in thinner layers.
Hydroperoxyl radical (HO2•) oxidizes dibromide radical anion (•Br2−) to bromine (Br2) in aqueous solution: Implications for the formation of Br2 in the marine boundary layer
Authors: Matthew Brendan M. , George Ingrid , Anastasio Cort
Published: December 2003

The release of photoactive halogen species such as Br2 from sea‐salt particles, snowpack, and sea‐ice can have significant effects on chemistry in the marine boundary layer (MBL). Although the reaction of hydroperoxyl radical (HO2•) with dibromide radical anion (•Br2−) might be a key step in the formation and release of Br2, there is currently no consensus on whether this reaction produces bromide (Br−) or molecular bromine (Br2). To address this question, we measured the formation of gaseous and aqueous oxidized bromide (primarily Br2) in illuminated bromide solutions as a function of pH. Results from these two sets of experimental data are best explained by kinetic models where HO2• oxidizes •Br2− to Br2. Using this reaction in a simple aerosol model reveals that the hydroxyl radical‐induced oxidation of particulate bromide, followed by reaction of •Br2− with HO2•, could be an important source of Br2 in the MBL.
A proxy for determining solar wind dynamic pressure at Mars using Mars Global Surveyor data
Authors: Crider Dana H. , Vignes Didier , Krymskii Alexander M. , Breus Tamara K. , Ness Norman F. , Mitchell David L. , Slavin James A. , Acuña Mario H.
Published: December 2003

We develop a method to infer the upstream solar wind pressure at Mars using data from the Mars Global Surveyor (MGS) magnetometer instrument. The method assumes magnetic field pressure in the magnetic pileup region balances the incident solar wind dynamic pressure. Newtonian pressure balance conditions are imposed for positions off of the subflow point. Proof of concept exists from the mapping phase of the spacecraft mission, when the orbital geometry at a constant altitude allows fits to magnetic field data as a function of solar zenith angle. During the elliptical orbit phase of MGS, when the spacecraft passes through a large range of altitudes, such fits are not possible. However, the measured magnetic pressure in the magnetic pileup region is scaled by the same means as derived for the mapping orbits and reasonable upstream solar wind pressure is obtained. We compare the distribution of solar wind pressure calculated using MGS data with the solar wind pressure measured upstream of the Earth during the same time period and find good agreement, further supporting this algorithm as a valid proxy for the incident solar wind pressure. The response of the position of the Magnetic Pileup Boundary to the inferred solar wind pressure also validates the method. High solar wind ram pressure depresses the altitude of the Magnetic Pileup Boundary.
Significance of lightning‐generated whistlers to inner radiation belt electron lifetimes
Authors: Rodger Craig J. , Clilverd Mark A. , McCormick Robert J.
Published: December 2003

The behavior of high‐energy electrons trapped in the Earth's Van Allen radiation belts has been extensively studied, through both experimental and theoretical techniques. While the evidence for whistler induced electron precipitation (WEP) from the radiation belts is overwhelming, and the mechanisms behind WEP are well understood, the overall significance of WEP on radiation belt loss rates has not been clear. In this paper we investigate the L‐shell variation and significance of WEP‐driven loss of Van Allen belt electrons by combining in situ measurements of electron precipitation, local WEP rates determined from Trimpi perturbations, and global lightning distributions. Our modeling suggests that long‐term WEP driven losses are more significant than all other inner radiation belt loss processes for electron kinetic energies in the range ∼50–150 keV in the L‐shell range L = 2–2.4. These calculated lifetimes are comparable to the observed decay rates of artificially injected high‐energy electrons. The upper energy limit of the WEP significance range increases with decreasing L to ∼225 keV at L = 2. For electron energies above this range manmade VLF transmitters and plasmaspheric hiss should dominate over all other loss processes. However, as our lifetimes are based on rather conservative parameter estimates, these conclusions should represent the lower bounds for the energy ranges over which WEP losses are significant. For lower L‐shells the coupling of lightning activity to the production of WEP events rapidly decreases, such that by L ∼ 1.7 WEP will be unimportant in the overall loss processes.
Linear mode conversion in inhomogeneous magnetized plasmas during ionospheric modification by HF radio waves
Authors: Gondarenko N. A. , Guzdar P. N. , Ossakow S. L. , Bernhardt P. A.
Published: December 2003

The propagation of high‐frequency (HF) radio waves in an inhomogeneous magnetoactive plasma and generation of plasma waves at the resonance layer near the reflection layer of the ordinary mode are studied using one‐dimensional (1‐D) and two‐dimensional full‐wave codes. The characteristics of the mode‐conversion process are investigated in linear and parabolic density profiles as the angle of incidence is varied. We present the 1‐D results for the wave propagation relevant to the high‐latitude heater facility at Tromsø and the midlatitude facility at Arecibo. For the facility at Arecibo, the 2‐D wave propagation in a plasma density approximating an overdense sporadic‐E patch is investigated to determine the localized regions of amplified intensity, where plasma waves can facilitate acceleration of fast energetic electrons, resulting in observed enhanced airglow.
MHD aspects of fire‐hose type instabilities
Authors: Wang B. J. , Hau L. N.
Published: December 2003

In a homogeneous anisotropic plasma the magnetohydrodynamic (MHD) shear Alfvén wave may become unstable for p∥ > p⟂ + B2/μo. Recently, a new type of fire‐hose instability was found by Hellinger and Matsumoto [2000] that has maximum growth rate occurring for oblique propagation and may grow faster than the Alfvén mode. This new mode is compressional and may be more efficient at destroying pressure anisotropy than the standard fire hose. This paper examines the fire‐hose type (p∥ > p⟂) instabilities based on the linear and nonlinear double‐polytropic MHD theory. It is shown that there exist two types of MHD fire‐hose instabilities, and with suitable choice of polytropic exponents the linear instability criteria become the same as those based on the Vlasov theory in the hydromagnetic limit. Moreover, the properties of the nonlinear MHD fire‐hose instabilities are found to have great similarities with those obtained from the kinetic theory and hybrid simulations. In particular, the classical fire‐hose instability evolves toward the linear fire‐hose stability threshold, while the nonlinear marginal stability associated with the new fire hose is well below the condition of β∥ − β⟂ = 2 but complies with less stringent linear stability threshold for compressible Alfvén waves.
Comparative study of bow shock models using Wind and Geotail observations
Authors: Dmitriev A. V. , Chao J. K. , Wu D. J.
Published: December 2003

Wind and Geotail observed bow shock (BS) crossings were selected from the 1998 to 2001 ISTP database. We analyzed 625 case events containing 4381 Geotail BS crossings and 130 case events containing 917 Wind BS crossings. The location of the BS crossings, in the aberrated GSE coordinate system, varied over a wide range from −85 Re to 45 Re along the X‐GSE axis, up to 90 Re in the perpendicular direction. ACE, Wind, and Geotail measurements were used to determine the upstream solar wind conditions in the interplanetary medium. These conditions were determined for the BS crossings in each case event by using the delay time of direct solar wind propagation from an upstream monitor to the probe satellite (Wind or Geotail). The solar wind conditions for the BS crossings varied over a wide range of dynamic pressures Pd (from 0.02 nPa to 49 nPa), IMF Bzs (from −26 nT to 23 nT), thermal/magnetic pressure ratios β (from 0.002 to 50), and magnetosonic Mach numbers Mms (from 1.02 to 29). Such a wide spatial and dynamic range of BS crossings permits us to consider the different parameters that control the BS size and shape, such as the radius of curvature of the magnetopause which depends on Pd and Bz, the Alfven, sonic, and magnetosonic Mach numbers, and the IMF orientation. To study the dependence on these parameters, we compared the accuracy of the BS models formulated by Peredo et al. [1995], Russell and Petrinec [1996], Verigin et al. [2001b], and Chao et al. [2002] for the prediction of selected BS crossings observed in different bow shock regions and with various upstream solar wind conditions. It was found that the Chao et al. [2002] model had the best capability for predicting the BS crossings. The solar wind dynamic pressure and magnetosonic Mach number were determined to be the most important parameters controlling the BS size and shape. The important role of the dawn‐dusk asymmetry of the bow shock tail region is emphasized. The effect of the southward IMF influence on the dayside magnetosheath thickness is revealed and discussed.
Effect of a large‐amplitude circularly polarized wave on linear beam‐plasma electromagnetic instabilities
Authors: Gomberoff L. , Hoyos J. , Brinca A. L.
Published: December 2003

In a previous paper, sufficiently large‐amplitude and left‐handed “pump waves” propagating parallel to the background magnetic field were shown to stabilize a moderately dense beam in a proton plasma against the generation of waves drawing their energy from the differential streaming motion of the beam [Gomberoff, 2003]. We now examine the general case of both left‐hand and right‐hand pump waves and their effects on beam instability as a function of pump wave amplitude and frequency, beam speed, and plasma component temperatures. We find that the left‐hand pump wave always gives beam stability above a threshold amplitude. Larger threshold trend with increasing beam speed and lower ones with increasing temperature. It is also shown that they can stabilize left‐hand polarized instabilities in the case of large drift velocities. The right‐hand pump similarly suppresses beam instabilities when its pump frequency is below the linearly unstable range of frequencies. However, when its pump frequency is within the range of instability, that part of the range below the pump frequency is stabilized beyond a threshold amplitude, but the part above becomes even more unstable in the presence of a right‐hand pump.
Testing the Hill model of transpolar potential saturation
Authors: Ober D. M. , Maynard N. C. , Burke W. J.
Published: December 2003

The Hill model predicts that the transpolar potential (ΦPC) saturates for strong solar wind electric fields (ESW) and saturates at higher values for larger solar wind ram pressures (PSW) and/or lower ionospheric Pedersen conductances (ΣP). Three months of Defense Meteorological Satellite Program (DMSP) measurements of polar cap potentials have been compared with predictions of the Hill model. Data from representative days that span a wide range of interplanetary and solar‐cycle conditions were selected for presentation. In the comparison we augmented the Hill model by adding a constant term to the magnetospheric potential and expressing ΣP in terms of the 10.7‐cm solar radio flux (F10.7). Temporal variations in observed ΦPC are in good agreement with the predictions of the augmented Hill model. Comparison of two events with significantly different average PSW but similar F10.7 and ESW found that DMSP observed higher potentials when PSW was larger. DMSP also observed higher potentials when ΣP was lower, when comparing two events with significantly different F10.7 (solar minimum versus solar maximum) but similar PSW and ESW. Both comparisons agree with the predictions of the Hill model.
Atmospheric losses of radiation belt electrons
Authors: Selesnick R. S. , Blake J. B. , Mewaldt R. A.
Published: December 2003

A numerical model of the low‐altitude energetic electron radiation belt, including the effects of pitch angle diffusion into the atmosphere and azimuthal drift, predicts lifetimes and longitude‐dependent loss rates as a function of electron energy and diffusion coefficient. It is constrained by high‐altitude (∼20,000 km) satellite measurements of the energy spectra and pitch angle distributions and then fit to low‐altitude (∼600 km) data that are sensitive to the longitude dependence of the electron losses. The fits provide estimates of the parameterized diffusion coefficient. The results show that the simple drift‐diffusion model can account for the main features of the low‐altitude radiation belt inside the plasmasphere during periods of steady decay. The rate of pitch angle diffusion is usually stronger on the dayside than on the nightside, frequently by a factor ∼10. The average derived lifetimes for loss into the atmosphere of ∼10 days are comparable to the observed trapped electron decay rates. Considerable variability in the loss rates is positively correlated with geomagnetic activity. The results are generally consistent with electron scattering by plasmaspheric hiss as the primary mechanism for pitch angle diffusion.
Observations of seasonal exchange through the Straits of Hormuz and the inferred heat and freshwater budgets of the Persian Gulf
Authors: Johns W. E. , Yao F. , Olson D. B. , Josey S. A. , Grist J. P. , Smeed D. A.
Published: December 2003

The exchange between the Persian (Arabian) Gulf and the Indian Ocean is investigated using hydrographic and moored acoustic Doppler current profiler data from the Straits of Hormuz during the period December 1996 to March 1998. The moored time series records show a relatively steady deep outflow through the strait from 40 m to the bottom with a mean speed of approximately 20 cm/s. A variable flow is found in the upper layer with frequent reversals on timescales of several days to weeks. The annual mean flow in the near‐surface layer is found to be northeastward (out of the Persian Gulf) in the southern part of the strait, suggesting a mean horizontal exchange with the Indian Ocean that is superimposed on the vertical overturning exchange driven by evaporation over the gulf. The salinity of the deep outflow varies from 39.3 to 40.8 psu with highest outflow salinities occurring in the winter months (December–March). The annual mean deep outflow through the strait is estimated to be 0.15 ± 0.03 Sv. Calculation of the associated heat and freshwater fluxes through the strait yields estimates for the annual heat loss over the surface of the gulf of −7 ± 4 W/m2 and an annual water loss (E‐P‐R) of 1.68 ± 0.39 m/yr. These values are shown to be in relatively good agreement with climatological surface fluxes derived from the Southampton Oceanography Centre global flux climatology after known regional biases in the radiative budget are taken into account.
Asian outflow and trans‐Pacific transport of carbon monoxide and ozone pollution: An integrated satellite, aircraft, and model perspective
Authors: Heald Colette L. , Jacob Daniel J. , Fiore Arlene M. , Emmons Louisa K. , Gille John C. , Deeter Merritt N. , Warner Juying , Edwards David P. , Crawford James H. , Hamlin Amy J. , Sachse Glen W. , Browell Edward V. , Avery Melody A. , Vay Stephanie A. , Westberg David J. , Blake Donald R. , Singh Hanwant B. , Sandholm Scott T. , Talbot Robert W. , Fuelberg Henry E.
Published: December 2003

Satellite observations of carbon monoxide (CO) from the Measurements of Pollution in the Troposphere (MOPITT) instrument are combined with measurements from the Transport and Chemical Evolution Over the Pacific (TRACE‐P) aircraft mission over the northwest Pacific and with a global three‐dimensional chemical transport model (GEOS‐CHEM) to quantify Asian pollution outflow and its trans‐Pacific transport during spring 2001. Global CO column distributions in MOPITT and GEOS‐CHEM are highly correlated (R2 = 0.87), with no significant model bias. The largest regional bias is over Southeast Asia, where the model is 18% too high. A 60% decrease of regional biomass burning emissions in the model (to 39 Tg yr−1) would correct the discrepancy; this result is consistent with TRACE‐P observations. MOPITT and TRACE‐P also give consistent constraints on the Chinese source of CO from fuel combustion (181 Tg CO yr−1). Four major events of trans‐Pacific transport of Asian pollution in spring 2001 were seen by MOPITT, in situ platforms, and GEOS‐CHEM. One of them was sampled by TRACE‐P (26–27 February) as a succession of pollution layers over the northeast Pacific. These layers all originated from one single event of Asian outflow that split into northern and southern plumes over the central Pacific. The northern plume (sampled at 6–8 km off California) had no ozone enhancement. The southern subsiding plume (sampled at 2–4 km west of Hawaii) contained a 8–17 ppbv ozone enhancement, driven by decomposition of peroxyacetylnitrate (PAN) to nitrogen oxides (NOx). This result suggests that PAN decomposition in trans‐Pacific pollution plumes subsiding over the United States could lead to significant enhancements of surface ozone.
Retrieval of the aerosol optical depth in the UV‐B at Uccle from Brewer ozone measurements over a long time period 1984–2002
Authors: Cheymol Anne , De Backer Hugo
Published: December 2003

Since 1984, Brewer spectrophotometer #16 has measured the ozone column at Uccle near Brussels in Belgium (50°48′N, 4°21′E, 100 m) from the direct sun observations at five isolated wavelengths in the UV‐B: 306.3 nm, 310.1 nm, 313.5 nm, 316.7 nm and 320.1 nm. We have used the Langley Plot Method (LPM) to retrieve the aerosol optical depth (AOD) from these observations over a long time period: from 1984 to November 2002. A seasonal variation of the AOD is clearly observed with mean AOD values of about 0.4 and 0.9 at 306.3 nm in winter and in summer respectively. The magnitude of these AODs is comparable to the AODs measured by AERONET sunphotometers at other places. We succeeded to demonstrate the impact of the eruption of Mount Pinatubo on the retrieved AOD in the UV‐B at Uccle in winter. Trend analysis on the mean annual AOD gives significant negative trends at the 2σ level only from 1989 to 2002 at all wavelengths and not over the whole period 1984–2002. The annual trend amounts to −2.46 ± 0.37%/year at 306.3 nm over 1989–2002. Significant negative seasonal trends at the 2σ level are only found in winter at all wavelengths (−2.66 ± 0.65%/year at 306.3 nm for example) and in summer at 306.3 nm (−1.24 ± 0.55%/year). In summer, in autumn and in spring at the other 4 wavelengths the trends are not significant at the 2σ level.
Twentieth‐century temperature and precipitation trends in ensemble climate simulations including natural and anthropogenic forcing
Authors: Broccoli Anthony J. , Dixon Keith W. , Delworth Thomas L. , Knutson Thomas R. , Stouffer Ronald J. , Zeng Fanrong
Published: December 2003

We present results from a series of ensemble integrations of a global coupled atmosphere‐ocean model for the period 1865–1997. Each ensemble consists of three integrations initialized from different points in a long‐running GFDL R30 coupled model control simulation. The first ensemble includes time‐varying forcing from greenhouse gases only. In the remaining three ensembles, forcings from anthropogenic sulfate aerosols, solar variability, and volcanic aerosols in the stratosphere are added progressively, such that the fourth ensemble uses all four of these forcings. The effects of anthropogenic sulfate aerosols are represented by changes in surface albedo, and the effects of volcanic aerosols are represented by latitude‐dependent perturbations in incident solar radiation. Comparisons with observations reveal that the addition of the natural forcings (solar and volcanic) improves the simulation of global multidecadal trends in temperature, precipitation, and ocean heat content. Solar and volcanic forcings are important contributors to early twentieth century warming. Volcanic forcing reduces the warming simulated for the late twentieth century. Interdecadal variations in global mean surface air temperature from the ensemble of experiments with all four forcings are very similar to observed variations during most of the twentieth century. The improved agreement of simulated and observed temperature trends when natural climate forcings are included supports the climatic importance of variations in radiative forcing during the twentieth century.
Interannual variations of stationary planetary wave activity in the northern winter troposphere and stratosphere and their relations to NAM and SST
Authors: Chen Wen , Takahashi Masaaki , Graf Hans‐F.
Published: December 2003

With the National Centers for Environmental Prediction‐National Center for Atmospheric Research (NCEP‐NCAR) reanalysis data from 1958 to 1998, two teleconnection patterns in the Eliassen‐Palm (EP) flux divergence field due to stationary planetary waves with wavenumbers (WNs) 1 to 3 are studied in the Northern Hemisphere winter. Both patterns appear as dipole structures with divergence of EP flux in the north and convergence in the south, or vice versa. One dipole evolves mainly in the stratosphere and is referred to as the stratospheric interannual oscillation (SIO). The other evolves mostly in the troposphere and is referred to as the tropospheric interannual oscillation (TIO). The TIO and the SIO are shown to be associated with anomalous meridional planetary wave propagation in the troposphere and stratosphere, respectively. The upward and poleward refraction of planetary waves into the polar waveguide across the tropopause is closely linked to the TIO. Examination of individual waves indicates that the tropospheric dipole of EP flux divergence comes basically from WN 3, whereas the stratospheric one comes totally from WNs 1 and 2. The reduced refraction of planetary waves into the polar waveguide across the tropopause associated with positive TIO index is dominantly contributed from both WNs 1 and 2. Regression and correlation analyses suggest that the TIO is closely related to the Northern Annular Mode (NAM). Its relation to the sea surface temperature (SST) is consistent with previous studies on the relation of NAM to SST. On the other hand, the SIO is shown to be closely associated with anomalous zonal mean winds in the subtropics of the midstratosphere and has a moderate correlation with an augmented Pacific‐North American (PNA) pattern in 500 hPa geopotential height. For the leading EOF of stratospheric variability the SIO accounts for a smaller fraction than the TIO. However, with the teleconnectivity in stratospheric EP flux divergence one can distinguish a stratospheric variation of anomalous north‐south planetary wave propagation from the total amount of wave activity entering the stratosphere, which may help us to understand the variability of transport circulation in the stratosphere. Significant correlation of SIO with tropical SST reveals that tropical SST is leading the SIO by up to around 9 months, which suggests a strong impact of El Niño/Southern Oscillation (ENSO) on the SIO. Planetary waves tend to be bent poleward in the midstratosphere when there is a warm event. The situation tends to be reverse during a cold event.
Isoprene emission from Indian trees
Authors: Varshney C. K. , Singh Abhai Pratap
Published: December 2003

Isoprene is the most dominant non‐methane volatile organic compound (NMVOC) emitted by plants. NMVOCs play an important role in regulating the composition of atmospheric trace gases including global concentration of tropospheric ozone. Our present knowledge about NMVOCs emission is mainly from studies on temperate tree species. So far information on biogenic NMVOCs emission from tropical tree species is limited. In this study, isoprene emission rates from 40 tropical Indian tree species belonging to 33 genera and 17 families were measured for the first time using a dynamic flow through enclosure chamber technique. The isoprene emission rate from plants (30°C and PAR 1000 μmolm−2s−1) ranged from undetectable to 81.5 μg g−1 h−1 and values were found to be comparable with other studies on tropical tree species. Tree species screened for isoprene emission in the present study may be grouped into the four categories, proposed by Karlik and Winer [2001], namely, 18 species were negligible or BDL isoprene emitting (<1 μg g−1 h−1), 6 species were low emitting (1 ≤ to <10 μg g−1 h−1), 5 species were moderate emitting (10≤ to <25 μg g−1 h−1), and 11 species were high isoprene emitting (≥25 μg g−1 h−1). Maximum isoprene emission rate (81.5 μg g−1 h−1) was observed in the case of Dalbergia sissoo Linn. It was interesting to find that Citrus limon Linn., Citrus reticulata Linn., Citrus sinensis Linn., Grevillea robusta A. Cunn., and Morus alba Linn., which were earlier reported as BDL or non isoprene emitters in US [Winer et al., 1998; Karlik and Winer, 2001] were found to be appreciably high isoprene emitters (0.61–21.60 μg g−1 h−1) in the present study.
Upper‐tropospheric inversion and easterly jet in the tropics
Authors: Fujiwara M. , Xie S.‐P. , Shiotani M. , Hashizume H. , Hasebe F. , Vömel H. , Oltmans S. J. , Watanabe T.
Published: December 2003

Shipboard radiosonde measurements revealed a persistent temperature inversion layer with a thickness of ∼200 m at 12–13 km in a nonconvective region over the tropical eastern Pacific, along 2°N, in September 1999. Simultaneous relative humidity measurements indicated that the thin inversion layer was located at the top of a very wet layer with a thickness of 3–4 km, which was found to originate from the intertropical convergence zone (ITCZ) to the north. Radiative transfer calculations suggested that this upper tropospheric inversion (UTI) was produced and maintained by strong longwave cooling in this wet layer. A strong easterly jet stream was also observed at 12–13 km, centered around 4°–5°N. This easterly jet was in the thermal wind balance, with meridional temperature gradients produced by the cloud and radiative processes in the ITCZ and the wet outflow. Furthermore, the jet, in turn, acted to spread inversions further downstream through the transport of radiatively active water vapor. This feedback mechanism may explain the omnipresence of temperature inversions and layering structures in trace gases in the tropical troposphere. Examination of high‐resolution radiosonde data at other sites in the tropical Pacific indicates that similar UTIs often appear around 12–15 km. The UTI around 12–15 km may thus be characterized as one of the “climatological” inversions in the tropical troposphere, forming the lower boundary of the so‐called tropical tropopause layer, where the tropospheric air is processed photochemically and microphysically before entering the stratosphere.
Paleofloods and historical floods of the Ardèche River, France
Authors: Sheffer N. A. , Enzel Y. , Benito G. , Grodek T. , Poart N. , Lang M. , Naulet R. , Cœur D.
Published: December 2003

Better understanding of flood occurrences and long‐term, floodplain planning, and flood risk assessment is achieved by integration of gauged, historical, and paleoflood data. The Ardèche River is ideal for this historical flood‐paleoflood study because its historical flood levels record dates back as early as A.D. 587 and useful data date back to A.D. 1522, its systematic gauging record is over 100 years long, and the geologic and geomorphic settings are optimal for paleoflood studies. Three sites provide three different thresholds for flood stages and SWD accumulation. According to our one‐dimensional (1‐D) step‐backwater calculations these three thresholds are 5200–5700 m3 s−1, 4900–5400 m3 s−1, and 3600–4000 m3 s−1 recording 6, 9, and 19 large Holocene floods, respectively. Dating the deposits enabled a correlation with the historical record. These paleoflood studies indicate that there are long gaps in flood occurrences on the Ardèche River; the floods are not randomly distributed in time but are clustered. They also indicate that the recent nineteenth century floods were the largest at the millennial timescale.
Effects of parasitism on the nutrient economy of sheep: an overview
Authors: Sykes A. R. , Greer A. W.
Published: December 2003

The experimental difficulties of qualifying the effects of gastrointestinal nematode parasitism on the nutrient economy of sheep from field and laboratory studies are discussed. The evidence available is reviewed and the conclusion drawn is that infection in the abomasum or small intestine induces protein deficiency while reducing supply through depression of appetite. It appears that the effects in susceptible animals — in lambs during the phase of initial acquisition of immunity and in ewes during the peripartum period — are largely reversible by protein supplementation. Quantified effects on mineral nutrition are few and are probably site-specific.The possibility that the host immune response per se may be implicated in the characteristic appetite depression is discussed. The need to understand the immune response's demand for specific amino acids is emphasised, particularly if nutritional supplements are to be used effectively in parasite control. A better understanding of the post-ruminal supply of amino acid in grazing animals will also be needed.
Mineral nutrition and its effects on gastrointestinal immune function of sheep
Authors: McClure S. J.
Published: December 2003

Sustainable control of gastrointestinal nematode parasitism requires optimisation of protective mucosal immunity. This may involve controlling predisposing factors, of which nutrition is the easiest to manipulate, or immuno-enhancement, including that by dietary components. Minerals are 1 type of dietary component with the potential to alter regulation of mucosal immunity to parasites.In addition to more specific functions, both major and trace elements have wide-ranging roles in the activity of enzyme systems, with the potential to affect immunity via a number of pathways. While there is little reported work on the effects of minerals on mucosal immunity of ruminants, some important principles can be drawn from this work. These are discussed with work on immunity in general. Also indicated is the future research needed to explain the role of minerals in immunity to internal parasites and to permit the application of this understanding to on-farm situations.