bluuebunny/crossref_metadata_2025 huggingface dataset:
Virus‐induced neuronal apoptosis as pathological and protective responses of the host
Authors: Mori Isamu , Nishiyama Yukihiro , Yokochi Takashi , Kimura Yoshinobu
Published: July 2004

Extensive efforts have been made to elucidate mechanisms by which viruses induce apoptosis in cultured neuronal cells. However, little is yet understood about the mechanisms of neuronal apoptosis in vivo as well as interpretations of this active host response. Here we review recent advances toward understanding these topics. The c‐Jun N‐terminal protein kinase cascade may be an important apoptotic mediator in virally infected neurons, which comes in focus as a therapeutic target for protecting neurons from death. A novel concept can be proposed that virus‐induced neuronal apoptosis in the central nervous system may represent a pathological host response, while that in the peripheral counterpart, especially olfactory receptor neurons, may mediate a protective host response. Copyright © 2004 John Wiley & Sons, Ltd.
Simian virus 40 (SV40) and human cancer: a review of the serological data
Authors: Shah Keerti V. , Galloway Denise A. , Knowles Wendy A. , Viscidi Raphael P.
Published: July 2004

Serum antibodies are widely utilised as specific and sensitive markers of virus infections but they have been employed relatively infrequently in the investigation of simian virus 40 (SV40) as a human carcinogen. In the past few years, serological data have become available which allow an examination of whether SV40 is currently circulating in human communities and if SV40 infection is associated with human cancer. The development of EIA with virus‐like particles (VLPs) of SV40, BKV and JCV has facilitated serological studies. Sera from macaques naturally infected with SV40 cross‐react unambiguously with BKV and JCV VLPs. Tests of over 9000 human sera with different immunological assays reveal a common pattern of SV40 reactivity. A small proportion of sera react at low titers and this reactivity is unrelated to age or the geographic location of the donor, but correlates with the presence and titers of BKV and JCV antibodies. Absorption with BKV and JCV VLPs decreases or abolishes the SV40 reactivity of human sera. The SV40 reactivity of sera from patients with mesothelioma, osteosarcoma or lymphomas, cancers which are reported to be associated with SV40, was similar to that in their controls or other comparison groups. The SV40 reactivity of human sera appears to be almost entirely a result of cross‐reactivity with BKV and JCV antibodies. Serological data thus do not support the possibility that SV40 is circulating in human communities or that it is associated with human cancer. Copyright © 2004 John Wiley & Sons, Ltd.
Habitat survey and classification of urban rivers
Authors: Davenport Angela J. , Gurnell Angela M. , Armitage Patrick D.
Published: July 2004

River surveys are undertaken for a variety of purposes including (i) to establish inventories of particular features and their changes, (ii) to collect data to underpin the classification of river types or to assess resources according to particular criteria, and (iii) to identify sites that have particular qualities or may require particular types of management. In this paper we describe a new reach‐scale survey technique, a range of synthetic indices, and a series of classifications specifically developed for application to urban rivers.

The Urban River Survey (URS) is developed from the River Habitat Survey (RHS) which is applied routinely to UK rivers. A number of important differences between the URS and RHS allow the former to provide improved discrimination between urban river channels to support management decision‐making. Urban river stretches are identified for survey according to their engineering type (a combination of planform, cross‐sectional form and level of reinforcement). The URS is then applied to stretches of a single engineering type and incorporates recording of (i) additional variables to the RHS that are particularly relevant to urban channels (e.g. indicators of pollution); (ii) improved resolution in the recording of some variables in comparison with the RHS (e.g. habitat features); and (iii) separation of layers of information that relate to the engineered (e.g. artificially introduced materials) and more natural (e.g. bank materials and morphological features) channel properties so that the interaction between these properties can be identified.

The URS is applied during two surveys of approximately 50 stretches of the River Tame, West Midlands, UK. The data are used to estimate a range of synthetic indices describing ‘Materials’, ‘Physical Habitat’ and ‘Vegetation’ attributes of urban river stretches. Cluster analysis is then applied to these indices to derive three classifications of urban river stretches. The similarity in classifications based on measurements from two different surveys indicates their robustness. Because the type of engineering applied to a stretch appears to have a significant influence on the class to which the stretch is allocated in each of the three classifications (with the strongest associations being apparent in the Materials classes and the weakest in the Vegetation classes), they can be used to explore the consequences of changed engineering, and the influence of scenarios of vegetation and water quality management can be additionally explored in relation to the Vegetation classification. Copyright © 2004 John Wiley & Sons, Ltd.
Modeling the effects of a log export ban in Indonesia
Authors: Dudley Richard G.
Published: July 2004

Because enforcement of forestry law has become extremely difﬁcult in Indonesia, a ban on export of logs has been suggested as a means of controlling over‐harvest and illegal logging. A model of a log export ban can help us visualize its effects on the forestry sector. The model consists of simpliﬁed overviews of: the wood processing sector, demand—price feedback loops, forest standing stock and log availability, log harvest capacity, and log exports. It examines important feedbacks that must be understood if the potential costs and beneﬁts of a log export ban are to be properly considered. Although some scenarios can help reduce log harvests to sustainable levels, others encourage expansion of small domestic milling capacity leading to increased log harvests. Excess domestic milling capacity added during a log export ban may continue to operate even after a log export ban is lifted. For a log export ban to be an effective tool in combating over‐harvest and illegal harvest, limits must also be placed on possible increases in domestic milling and logging capacity. Copyright © 2004 John Wiley & Sons, Ltd
Models for management of wildlife populations: lessons from spectacled bears in zoos and grizzly bears in Yellowstone
Authors: Faust Lisa J. , Jackson Rosemary , Ford Andrew , Earnhardt Joanne M. , Thompson Steven D.
Published: July 2004

Models of population dynamics are frequently used in the management and conservation of wildlife populations. They provide a powerful method of quantitatively assessing a population's risk of decline and determining the potential to reverse the decline. Models from recent studies of managed populations are presented. The ﬁrst model simulates the spectacled bear populations maintained in American Zoo and Aquarium Association (AZA) zoos. The second model simulates the grizzly bear population in the Greater Yellowstone Ecosystem (GYE). The article concludes with a discussion of system dynamics modeling in the larger context of population dynamics modeling. Copyright © 2004 John Wiley & Sons, Ltd.
Activation of 5‐HT2 receptors enhances the release of acetylcholine in the prefrontal cortex and hippocampus of the rat
Authors: Nair Sunila G. , Gudelsky Gary A.
Published: July 2004

The role of 5‐HT2 receptors in the regulation of acetylcholine (ACh) release was examined in the medial prefrontal cortex and dorsal hippocampus using in vivo microdialysis. The 5‐HT2A/2C agonist ±1‐(2,5‐dimethoxy‐4‐iodophenyl) ‐2‐ aminopropane hydrochloride (DOI) (1 and 2 mg/kg, i.p.) significantly increased the extracellular concentration of ACh in both brain regions, and this response was attenuated in rats treated with the 5‐HT2A/2B/2C antagonist LY‐53,857 (3 mg/kg, i.p.). Treatment with LY‐53,857 alone did not significantly alter ACh release in either brain region The 5‐HT2C agonist 6‐chloro‐2‐(1‐piperazinyl)‐pyrazine) (MK‐212) (5 mg/kg, i.p.) significantly enhanced the release of ACh in both the prefrontal cortex and hippocampus, whereas the 5‐HT2 agonist mescaline (10 mg/kg, i.p.) produced a 2‐fold increase in ACh release only in the prefrontal cortex. Intracortical, but not intrahippocampal, infusion of DOI (100 μM) significantly enhanced the release of ACh, and intracortical infusion of LY‐53,857 (100 μM) significantly attenuated this response. These results suggest that the release of ACh in the prefrontal cortex and hippocampus is influenced by 5‐HT2 receptor mechanisms. The increase in release of ACh induced by DOI in the prefrontal cortex, but not in the hippocampus, appears to be due to 5‐HT2 receptor mechanisms localized within this brain region. Furthermore, it appears that the prefrontal cortex is more sensitive than the dorsal hippocampus to the stimulatory effect of 5‐HT2 agonists on ACh release. Synapse 53:202–207, 2004. © 2004 Wiley‐Liss, Inc.
Review of state‐of‐the‐art and output characteristics of table‐top soft x‐ray lasers
Authors: Janulewicz K. A. , Lucianetti A. , Priebe G. , Nickles P. V.
Published: July 2004

X‐ray lasers (XRLs) belong to the brightest existing short‐wavelength sources. The development trends are discussed from the point of view their suitability for applications. A detailed analysis of the output parameters of the XRL with transient inversion proves that this type of laser has become sufficiently mature to be applied in practice. Copyright © 2004 John Wiley & Sons, Ltd.
Giotto in the Chapel of the Scrovegni: EDXRF analysis of the golden haloes with portable equipment
Authors: Cesareo Roberto , Castellano Alfredo , Buccolieri Giovanni , Quarta Stefano , Marabelli Maurizio
Published: July 2004

Energy‐dispersive x‐ray fluorescence (EDXRF) analysis is particularly suited to analyse paintings, because it does not significantly damage the sample and allows the measurement of several elements in a single measurement. The use of portable equipment allows a completely non‐destructive analysis, although the interpretation of the measured spectra requires a more accurate approach.

EDXRF analysis of paintings generally gives the following information: identification of the elements, and therefore pigments, employed by the artist; possible presence of elements on the surface (sulphur, chlorine) due to pollution effects; identification of previous restoration areas, through the presence of ‘modern’ elements, such as titanium, zinc, cadmium and others.

Recently, the famous Chapel of the Scrovegni, painted by Giotto in Padua in 1303–05, was analysed in detail to obtain the above information and, more specifically, to analyse the golden haloes. In this paper the measurement of sulphur on the surface of the frescoes is described, together with the composition of the golden haloes. Copyright © 2004 John Wiley & Sons, Ltd.
Experimental and numerical investigation of edge tones
Authors: Bamberger A. , Bänsch E. , Siebert K.G.
Published: July 2004

We study both, by experimental and numerical means the fluid dynamical phenomenon of edge tones. Of particular interest is the verification of scaling laws relating the frequency f to given quantities, namely d, the height of the jet, w, the stand–off distance and the velocity of the jet. We conclude that the Strouhal number Sd is related to the geometrical quantities through Sd = C ⋅ (d / w)n with n ≈ 1, in contrast to some analytical treatments of the problem. The constant C of the experiment agrees within 13–15% with the result of the numerical treatment. Only a weak dependence on the Reynolds number with respect to d is observed. In general, a very good agreement of the experimental and the numerical simulations is found.
Prostaglandin production by melanocytic cells and the effect of α‐melanocyte stimulating hormone
Authors: Nicolaou Anna , Estdale Sian E , Tsatmali Marina , Herrero Daniel Pascual , Thody Anthony J
Published: July 2004

Prostaglandins are potent mediators of the inflammatory response and are also involved in cancer development. In this study, we show that human melanocytes and FM55 melanoma cells express cyclooxygenase‐1 and ‐2 (COX‐1 and ‐2) and thus have the capability to produce prostaglandins. The FM55 cells produced predominantly PGE2 and PGF2α, whereas the HaCaT keratinocyte cell line produced mainly PGE2. The anti‐inflammatory peptide, α‐melanocyte stimulating hormone (α‐MSH), reduced prostaglandin production in FM55 and HaCaT cells and reversed the effect of the pro‐inflammatory cytokine TNF‐α in the former. These results indicate that melanocytes produce prostaglandins and that α‐MSH, by inhibiting this response, may play an important role in regulating inflammatory responses in the skin.
Biophysical characterization of natural and mutant fluorescent proteins cloned from zooxanthellate corals
Authors: Sun Yi , Castner Edward W. , Lawson Catherine L. , Falkowski Paul G.
Published: July 2004

Two novel colored fluorescent proteins were cloned and biophysically characterized from zooxanthellate corals (Anthozoa). A cyan fluorescent protein derived from the coral Montastrea cavernosa (mcCFP) is a trimeric complex with strong blue‐shifted excitation and emission maxima at 432 and 477 nm, respectively. The native complex has a fluorescence lifetime of 2.66 ± 0.01 ns and an inferred absolute quantum yield of 0.385. The spectroscopic properties of a green fluorescent protein cloned from Meandrina meandrites (mmGFP) resemble the commercially available GFP derived originally from the hydrozoan Aequorea victoria (avGFP). mmGFP is a monomeric protein with an excitation maximum at 398 nm and an emission maximum at 505 nm, a fluorescence lifetime of 3.10 ± 0.01 ns and an absolute quantum yield of 0.645. Sequence homology with avGFP and the red fluorescent protein (DsRed) indicates that the proteins adopt the classic β‐barrel configuration with 11 β‐strands. The three amino acid residues that comprise the chromophore are QYG for mcCFP and TYG for mmGFP, compared with SYG for avGFP. A single point mutation, Ser‐110 to Asn, was introduced into mmGFP by random mutagenesis. Denaturation and refolding experiments showed that the mutant has reduced aggregation, increased solubility and more efficient refolding relative to the wild type. Time‐resolved emission lifetimes and anisotropies suggest that the electronic structure of the chromophore is highly dependent on the protonation state of adjoining residues.
Fine‐tuning the hydrophobicity of a mitochondria‐targeted antioxidant
Authors: Asin-Cayuela Jordi , Manas Abdul-Rahman B. , James Andrew M. , Smith Robin A.J. , Murphy Michael P.
Published: July 2004

The mitochondria‐targeted antioxidant MitoQ comprises a ubiquinol moiety covalently attached through an aliphatic carbon chain to the lipophilic triphenylphosphonium cation. This cation drives the membrane potential‐dependent accumulation of MitoQ into mitochondria, enabling the ubiquinol antioxidant to prevent mitochondrial oxidative damage far more effectively than untargeted antioxidants. We sought to fine‐tune the hydrophobicity of MitoQ so as to control the extent of its membrane binding and penetration into the phospholipid bilayer, and thereby regulate its partitioning between the membrane and aqueous phases within mitochondria and cells. To do this, MitoQ variants with 3, 5, 10 and 15 carbon aliphatic chains were synthesised. These molecules had a wide range of hydrophobicities with octan‐1‐ol/phosphate buffered saline partition coefficients from 2.8 to 20 000. All MitoQ variants were accumulated into mitochondria driven by the membrane potential, but their binding to phospholipid bilayers varied from negligible for MitoQ3 to essentially total for MitoQ15. Despite the span of hydrophobicites, all MitoQ variants were effective antioxidants. Therefore, it is possible to fine‐tune the degree of membrane association of MitoQ and other mitochondria targeted compounds, without losing antioxidant efficacy. This indicates how the uptake and distribution of mitochondria‐targeted compounds within mitochondria and cells can be controlled, thereby facilitating investigations of mitochondrial oxidative damage.
Tomatidine and lycotetraose, hydrolysis products of α‐tomatine by Fusarium oxysporum tomatinase, suppress induced defense responses in tomato cells
Authors: Ito Shin-ichi , Eto Tomomi , Tanaka Shuhei , Yamauchi Naoki , Takahara Hiroyuki , Ikeda Tsuyoshi
Published: July 2004

Many fungal pathogens of tomato produce extracellular enzymes, collectively known as tomatinases, that detoxify the preformed antifungal steroidal glycoalkaloid α‐tomatine. Tomatinase from the vascular wilt pathogen of tomato Fusarium oxysporum f. sp. lycopersici cleaves α‐tomatine into the aglycon tomatidine (Td) and the tetrasaccharide lycotetraose (Lt). Although modes of action of α‐tomatine have been extensively studied, those of Td and Lt are poorly understood. Here, we show that both Td and Lt inhibit the oxidative burst and hypersensitive cell death in suspension‐cultured tomato cells. A tomatinase‐negative F. oxysporum strain inherently non‐pathogenic on tomato was able to infect tomato cuttings when either Td or Lt was present. These results suggest that tomatinase from F. oxysporum is required not only for detoxification of α‐tomatine but also for suppression of induced defense responses of host.
Tree-ring-based mass-balance estimates for the past 300 years at Peyto Glacier, Alberta, Canada
Authors: Watson Emma , Luckman Brian H
Published: July 2004

Tree rings were used to reconstruct mass balance for Peyto Glacier in the Canadian Rocky Mountains from A.D. 1673 to 1994. Summer balance was reconstructed from tree-ring estimates of summer temperature and precipitation in the Canadian Rockies. Winter balance was derived from tree-ring data from sites bordering the Gulf of Alaska and in western British Columbia. The models for winter and summer balance each explain over 40% of the variance in the appropriate mass-balance series. Over the period 1966–1994 the correlation between the reconstructed and measured net balances is 0.71. Strong positive mass balances are reconstructed for 1695–1720 and 1810–1825, when higher winter precipitation coincided with reduced ablation. Periods of reconstructed positive mass balance precede construction of terminal moraines throughout the Canadian Rockies ca. 1700–1725 and 1825–1850. Positive mass balances in the period 1845–1880 also correspond to intervals of glacier readvance. Mass balances were generally negative between 1760 and 1805. From 1673 to 1883 the mean annual net balance was +70 mm water equivalent per year (w.e./yr.), but it averaged −317 mm w.e./yr from 1884 to 1994. This reconstructed mass balance history provides a continuous record of glacier change that appears regionally representative and consistent with moraine and other proxy climate records.
Medical futility
Authors: Committee on Ethics
Published: July 2004

It is difficult to define medical futility prospectively and objectively. Nonetheless, as technology continues to advance and use more resources, it is important that physicians and their institutions develop a process for dealing with conflict surrounding the construct of medical futility.

Prospective policies on medical futility are preferable to unilateral decision making by individual physicians. Such a medical futility policy should provide a systematic process for dealing with disagreements and for reaching a fair resolution, as outlined previously. When there is disagreement, patient and family values regarding treatment options and the default position of maintaining life ordinarily should take priority. However, situations may occur in which claims of reasonableness and equity in the distribution of resources are so powerful that the views of caregivers, the institution, and society will prevail.
Air travel during pregnancy
Authors: Committee on Obstetric Practice
Published: July 2004

In the absence of obstetric or medical complications, pregnant women can observe the same general precautions for air travel as the general population and can fly safely up to 36 weeks of gestation. In‐craft environmental conditions, such as low cabin humidity and changes in cabin pressure, coupled with the physiologic changes of pregnancy, do result in maternal adaptations, which could have transient effects on the fetus. Pregnant air travelers with medical problems that may be exacerbated by a hypoxic environment, but who must travel by air, should be prescribed supplemental oxygen during air travel. Pregnant women at significant risk for preterm labor or with placental abnormalities should avoid air travel. Because air turbulence cannot be predicted and the risk for trauma is significant, pregnant women should be instructed to continuously use their seat belts while seated, as should all air travelers. Pregnant air travelers may take precautions to ease in‐flight discomfort, and although no hard evidence exists, preventive measures can be employed to minimize risks.
Editorial Board 1998
Authors: Lahey Karen Eilers
Published: July 2004

NA
Cardiac rehabilitation of older patients
Authors: West Robert
Published: July 2004

Rehabilitation is a necessary step in the process of recovery from most serious illness and from many clinical interventions. The nature of rehabilitation, and the form of any programme of rehabilitation provided to help patients with this process, depends greatly on patient, illness, treatment or intervention, co-morbidity and on the availability of appropriate services. Heart disease is the leading cause of death in most developed countries and acute myocardial infarction (MI) is a major cause of acute medical admissions to hospitals, and revascularization by coronary artery bypass graft surgery (CABG) is a leading surgical intervention. Both MI and CABG involve a day or more in intensive care followed by several days recuperation in hospital. There is a fairly obvious case for rehabilitation for patients surviving the truly life-threatening experience of MI (20% sudden deaths and a further 10% die within 24 hours of onset of pain), and for patients following the major ‘trauma’ of open heart surgery (operative mortality about 1%). The specific needs of these two groups may differ because their experiences differ; one medical the other surgical, and, possibly more significantly, one unexpected, the other planned.
Gene therapy for severe combined immune deficiency
Authors: Qasim Waseem , Gaspar H. Bobby , Thrasher Adrian J.
Published: July 2004

Infants born with severe combined immune deficiencies are prone to life-threatening infections and, without treatment, do not survive beyond the first year of life. Haematopoietic stem cell transplantation from a fully matched donor offers the possibility of cure. In the absence of a suitable matched donor, haploidentical transplants from a parental donor may be undertaken, but these are associated with more complications and lower success rates. Recently, an alternative therapeutic option based on retroviral gene delivery has been used to correct X-linked severe combined immune deficiency (SCID-X1) and adenosine deaminase deficiency. Clinical trials have established that in situations where ex vivo gene transfer into haematopoietic progenitor cells confers a strong selective advantage, the procedure is a feasible alternative to haploidentical transplantation, with favourable kinetics of immune reconstitution.
Assessment of Divided Attention: Development of a New Dual-Task Procedure
Authors: Macek Cornelia , Brinkers Ina , Beblo Thomas , Hartje Wolfgang
Published: July 2004

Abstract: A computerized dual-task procedure for the assessment of divided attention is described, which does not only allow for the concurrent presentation of visual and auditory stimuli, but also, by supplying two response keys, for the simultaneous occurrence of critical (to-be-responded-to) events in both stimulus channels. In scoring the performance, the two keys are always considered in conjunction, i.e., a response is scored as correct only if the two keys are handled in agreement with the pertaining constellation of the visual and auditory stimulation. The task was applied with 48 young healthy subjects. Analysis of the data with respect to item difficulty, reliability and validity supports the usefulness of the procedure. In order to obtain preliminary information on the clinical practicability of the procedure the task was also administered to 31 brain-damaged in-patients of a neurological rehabilitation center.
Symptomvalidierungstests in der neuropsychologischen Diagnostik: eine Analogstudie
Authors: Merten Thomas , Henry Matthias , Hilsabeck Robin
Published: July 2004

Zusammenfassung: In der neuropsychologischen Diagnostik, mehr noch aber in der Begutachtung gewinnen Symptomvalidierungstests (SVT) zur Untersuchung der Leistungsmotivation zunehmend an Bedeutung. In einer Analogstudie wurde die Güte zweier international bekannter Verfahren (Word Memory Test; Amsterdam Short Term Memory Test) sowie einer Neuentwicklung (Word Completion Memory Test) untersucht. Zusätzlich wurden Leistungstests eingesetzt: der Trail Making Test (TMT), der Complex Figure Test sowie die Standard Progressive Matrices (SPM). Eine Gruppe von 10 experimentellen Simulanten wurde spezifisch auf die Vortäuschung von Gedächtnisstörungen vorbereitet, während eine Kontrollgruppe (n = 10) optimale Testanstrengung zeigen sollte. Alle SVT führten im Gegensatz zu den Simulationsmarkern des TMT und der SPM zu einer ausgezeichneten Klassifikationsgüte (95-100 %). Die neuropsychologischen Leistungsmaße wiesen zwar signifikante Gruppenunterschiede aus, zeigten aber auch eine nicht unbedeutende Überlappung der Verteilungen. Mehr Studien sind notwendig, um den SVT in den deutschsprachigen Ländern den Platz zu sichern, den sie international aktuell in der klinisch-neuropsychologischen Forschung und Praxis einnehmen.
Solar cycle variability of nighttime topside helium ion concentrations over Arecibo
Authors: González Sixto A. , Sulzer Michael P. , Nicolls Michael J. , Kerr Robert B.
Published: July 2004

The incoherent scatter radar mode and data extraction method used in topside experiments at the Arecibo Observatory are discussed. Helium ion concentrations in the lower topside ionosphere over Arecibo are presented for low and high solar flux periods of the same season (October). Data from 8–9 October 1988, 21–22 October 1995, 26–27 October 1997, and 12–13 October 2001 are compared. The data from October 1988 and 2001 are representative of high solar flux conditions, while the other two periods (1995 and 1997) are from low solar flux conditions. All data sets represent geomagnetic quiet periods over Arecibo and serve as examples of typical equinox topside conditions. For solar minimum the altitude distribution of the helium ions usually has a maximum near the O+ to H+ transition altitude () during the night, usually around 550–650 km. The He+ number densities tend to be quite low, 2 or 3 × 103 cm−3 or <15% of the topside plasma density at the peak of the layer. For the higher solar flux case, however, He+ forms a more distinct layer at an altitude that is slightly above at night. The O+‐to‐He+ transition altitude () is reported to be below after the postsunset collapse in these solar‐maximum conditions, meaning that He+ is the dominant species. We find that the relative abundance of He+ can reach 60–65% of the topside plasma at the peak of this layer during these equinox conditions or up to 4 × 104 cm−3, with as low as 700 km and the He+ to H+ transition () extending over 1000 km at night.
Empirical model of nitric oxide in the lower thermosphere
Authors: Marsh D. R. , Solomon S. C. , Reynolds A. E.
Published: July 2004

The Student Nitric Oxide Explorer (SNOE) satellite made near‐continuous measurements of nitric oxide in the lower thermosphere (97.5 km to 150 km) between March 1998 and September 2000. Using eigenanalysis, this daily nitric oxide data set is represented as a time mean plus the sum of orthogonal functions of space multiplied by time‐varying coefficients. The functions, typically called empirical orthogonal functions (EOFs), are ordered by the amount of variance they capture from the original data set. While this analysis in no way guarantees that the modes of variability identified by the EOFs are associated with physical processes, we show that it is clearly so for the first three EOFs of the SNOE data set. The dominant mode of variability is associated with auroral activity, followed by a seasonal effect, and then a response to varying solar EUV flux. As a result, it is possible to construct a compact, three‐dimensional nitric oxide empirical model (NOEM) in the lower thermosphere that takes as input a planetary magnetic index, day of year, and 10.7 cm solar radio flux. Since it is possible that changes in lower thermospheric nitric oxide could lead to changes in stratospheric ozone, the model presented here can be utilized in climate simulations without the need to incorporate many thermospheric processes.
Siliceous phytoplankton production and export related to trans‐frontal dynamics of the Almeria‐Oran frontal system (western Mediterranean Sea) during winter
Authors: Leblanc K. , Quéguiner B. , Prieur L. , Claustre H. , Oubelkheir K. , Bruyant F.
Published: July 2004

A study of the biogeochemical properties of the Almeria‐Oran front was carried out in December 1997 to January 1998. A strong salinity gradient between Atlantic and Mediterranean waters in the Alboran Sea allowed the differentiation of several subsystems: the Mediterranean waters, the frontal zone, and the anticyclonic gyre. Si and C biomass and production were clearly enhanced by the frontal dynamics on the Atlantic side of the jet while Mediterranean waters, which encountered severe nutrient depletion in the mixed layer, exhibited a typical oligotrophic regime. The distribution of particulate matter was controlled by a cross‐frontal downwelling along the isopycnal slopes, that shoaled to the surface on the dense Mediterranean side and deepened toward the Atlantic side of the jet. A strong decoupling of production and biomass maximums occurred between the frontal limit, where particulate matter was produced, and the gyre, where it was accumulated. Export fluxes at 300 m were low at the frontal limit, representing 1–2% of surface Si and C production, and it is hypothesized that advective fluxes rather than grazing were the main factor limiting the accumulation of biomass. The adjacent systems, namely the associated anticyclonic gyre and the Mediterranean waters, were exporting Si to depth more efficiently than the frontal zone. The Si and C decoupling with depth appeared higher in the Almeria‐Oran frontal system than in other open‐ocean zones. The integrated Si production at the Almeria‐Oran Front was 0.83 mmol Si m−2d−1, which was closest to the production rates of mid‐ocean oligotrophic gyres than of other frontal systems, and may be explained by the sampling period, which occurred in the winter season.
Temporal and spatial variations in R:P ratios in Lake Superior, an oligotrophic freshwater environment
Authors: Russ Mary E. , Ostrom Nathaniel E. , Gandhi Hasand , Ostrom Peggy H. , Urban Noel R.
Published: July 2004

A study of respiration to photosynthesis (R:P) ratios in Lake Superior, based on the fraction of O2 saturation and the isotopic composition of O2, was undertaken to evaluate spatial and temporal variations in the trophic status of a large oligotrophic freshwater environment. The lake was predominantly net heterotrophic from April to October 2000 (R:P ratios: 1.2–2.5). Uniform R:P ratios of ∼1.5 with depth and across the lake in April 2000 and 2001 revealed the homogeneity of the water column during spring. A brief period of net autotrophy was observed during summer thermal stratification in 2000 and 2001, and surveys showed this condition to be prevalent and lake‐wide in August 2001 (R:P ratios: 0.5–0.9). Strong net autotrophy (R:P ratios: 0.6) was found near Duluth, Minnesota, and suggested the potential for the formation of mesotrophic conditions within areas of increased nutrient loadings from urbanization. Respiration and photosynthesis were shown to exert a strong control on O2 gas exchange within Lake Superior, as evidenced by significant correlations between R:P ratios and O2 gas exchange during periods of net heterotrophy and autotrophy. This observation was unexpected since [O2] in the lake appears to be dominated by atmospheric O2 gas exchange, given that the fraction of O2 saturation is continuously near levels expected for equilibration with the atmosphere. Furthermore, the relationship between the biological and physical O2 fluxes may enable the use of R:P ratios to calculate O2 gas exchange and ultimately estimate CO2 fluxes between lakes and the atmosphere.
Volatile organic compound measurements at Trinidad Head, California, during ITCT 2K2: Analysis of sources, atmospheric composition, and aerosol residence times
Authors: Millet Dylan B. , Goldstein Allen H. , Allan James D. , Bates Timothy S. , Boudries Hacene , Bower Keith N. , Coe Hugh , Ma Yilin , McKay Megan , Quinn Patricia K. , Sullivan Amy , Weber Rodney J. , Worsnop Douglas R.
Published: July 2004

We report hourly in‐situ observations of C1‐C8 speciated volatile organic compounds (VOCs) obtained at Trinidad Head CA in April and May 2002 as part of the NOAA Intercontinental Transport and Chemical Transformation study. Factor analysis of the VOC data set was used to define the dominant processes driving atmospheric chemical composition at the site, and to characterize the sources for measured species. Strong decreases in background concentration were observed for several of the VOCs during the experiment due to seasonal changes in OH concentration. CO was the most important contributor to the total measured OH reactivity at the site at all times. Oxygenated VOCs were the primary component of both the total VOC burden and of the VOC OH reactivity, and their relative importance was enhanced under conditions when local source contributions were minimal. VOC variability exhibited a strong dependence on residence time (slnX = 1.55τ−0.44, r2 = 0.98; where slnX is the standard deviation of the natural logarithm of the mixing ratio), and this relationship was used, in conjunction with measurements of 222Rn, to estimate the average OH concentration during the study period (6.1 × 105 molec/cm3). We also employed the variability‐lifetime relationship defined by the VOC data set to estimate submicron aerosol residence times as a function of chemical composition. Two independent measures of aerosol chemical composition yielded consistent residence time estimates. Lifetimes calculated in this manner were between 3–7 days for aerosol nitrate, organics, sulfate, and ammonium. The lifetime estimate for methane sulfonic acid (∼12 days) was slightly outside of this range. The lifetime of the total aerosol number density was estimated at 9.8 days.
Measurement and analysis of aerosol and black carbon in the southwestern United States and Panama and their dependence on air mass origin
Authors: Junker C. , Sheahan J. N. , Jennings S. G. , O'Brien P. , Hinds B. D. , Martinez‐Twary E. , Hansen A. D. A. , White C. , Garvey D. M. , Pinnick R. G.
Published: July 2004

Total aerosol mass loading, aerosol absorption, and black carbon (BC) content were determined from aerosol collected on 598 quartz fiber filters at a remote, semiarid site near Orogrande, New Mexico from December 1989 to October 1995. Aerosol mass was determined by weighing filters before and after exposure, and aerosol absorption was determined by measuring the visible light transmitted through loaded filter samples and converting these measurements to aerosol absorption. BC content was determined by measuring visible light transmitted through filter samples before and after firing and converting the absorption to BC mass, assuming a BC absorption cross section of 19 m2/g in the fiber filter medium. Two analyses were then performed on each of the logged variables: an autoregressive integrating moving average (ARIMA) analysis and a decomposition analysis using an autoregressive model to accommodate first‐order autocorrelation. The two analyses reveal that BC mass has no statistically significant seasonal dependence at the 5% level of significance but only random fluctuations varying around an average annual value that has a long‐term decreasing trend (from 0.16 to 0.11 μg/m3 during 1990–1995). Aerosol absorption, which is dominated by BC, also displays random fluctuations about an average value, and decreases from 1.9 Mm−1 to 1.3 Mm−1 during the same period. Unlike BC, aerosol mass at the Orogrande site displays distinctly different character. The analyses reveal a pronounced seasonal dependence, but no long‐term trend for aerosol mass. The seasonal indices resulting from the autoregression analysis have a minimum in January (−0.78) and maximum in June (+0.58). The geometric mean value over the 1990–1995 period for aerosol mass is 16.0 μg/m3. Since BC aerosol at the Orogrande site is a product of long‐range atmospheric transport, a back trajectory analysis of air masses was conducted. Back trajectory analyses indicate that air masses traversing high population centres on the west coast of the USA can lead to significant BC loading, while air masses originating from the southeast of the site tend to have less BC. Additional aerosol measurements are reported for a remote maritime site located on the Atlantic side of the former Panama Canal Zone for the 1976–1979 period, although these data have been analyzed with less statistical rigor. The average geometric mean value of aerosol mass loading for this site is 9.7 μg/m3, with a significant decreasing trend of −19% per year. The mean value of aerosol absorption is 0.59 Mm−1, with a decreasing trend of −15% per year.
Photochemical production of carbonyl sulfide in precipitation
Authors: Mu Yujing , Geng Chunmei , Wang Meizhen , Wu Hai , Zhang Xiaoshan , Jiang Guibin
Published: July 2004

Precipitation samples (rain and snow) from 10 provinces in China were collected during the winter season. The concentration of initial dissolved carbonyl sulfide (COS) and its photochemical production rates by natural sunlight were measured. All investigated precipitation samples were found to be supersaturated with COS, and the initial dissolved COS concentrations were in the range from 17.7 to 48.2 ng L−1. The COS saturation ratios (SR) for the investigated samples were in the range from 15.8 to 60.4. The COS photochemical production rates depended strongly on sunlight intensity and were independent of microbial activity as well as dissolved O2. The amount of COS produced photochemically by sunlight irradiation for 14 to 50 days was ∼1–2 orders of magnitude greater than that of initial dissolved COS.
Submicron aerosol composition at Trinidad Head, California, during ITCT 2K2: Its relationship with gas phase volatile organic carbon and assessment of instrument performance
Authors: Allan James D. , Bower Keith N. , Coe Hugh , Boudries Hacene , Jayne John T. , Canagaratna Manjula R. , Millet Dylan B. , Goldstein Allen H. , Quinn Patricia K. , Weber Rodney J. , Worsnop Douglas R.
Published: July 2004

Two Aerodyne aerosol mass spectrometers (AMSs) were deployed at Trinidad Head on the north Californian coast during the National Oceanographic and Atmospheric Administration Intercontinental Transport and Chemical Transformation 2002 (ITCT 2K2) experiment, to study the physiochemical properties of submicron aerosol particles within the Pacific marine boundary layer. One AMS was modified to allow the study of sea salt‐based particles, while the other used a temperature cycling system on its inlet. The reported loadings increased by a factor of 2 when the temperature approached the dew point, which is due to the inlet performance and has implications for other AMS experiments and applications. The processed data were compared with those of a particle into liquid sampler‐ion chromatograph and showed that the ammonium, sulfate and organic fractions of the particles were consistently found within a single, normally acidic, accumulation mode at around 300–400 nm. However, when influenced by land‐based sources, vehicle emissions and increased ammonium loadings were seen. The concentrations of nitrate in the accumulation mode were low, but it was also found within sea salt particles in the coarse mode and can be linked to the displacement of chloride. The organic fraction showed a high degree of chemical ageing and evidence of nitrogen‐bearing organics was also observed. The particulate organic data were compared to the volatile organic carbon data derived from an in‐situ gas chromatograph‐mass spectrometer‐flame ionization detector and relationships were found between the gas and particle phase chemicals in both the overall concentrations and the levels of oxidation.
Significant dust simulation differences in nudged and climatological operation mode of the AGCM ECHAM
Authors: Timmreck C. , Schulz M.
Published: July 2004

The geographical distribution and the seasonal variability of soil dust aerosol have been investigated with the climate model ECHAM4. Two experiments have been performed: a climatological with prescribed climatological sea surface temperatures (CLIM) and a nudged where the model is forced by ECMWF Reanalysis data of the particular years 1986–1991 (NUDGE). The mean geographical distribution and the seasonal variability of mineral dust alter between the different modes of operation of the climate model. Largest deviations occur in Northern Hemisphere winter and are related to the overestimation and the mislocation of the Azores high in ECHAM4. The Saharan dust plume is shifted farther north in CLIM compared to NUDGE and Meteosat satellite observations with significant implication for the cross‐Atlantic transport. In the dust source regions the wind speed distribution is slightly shifted and creates a twofold difference in total dust emissions. Our results indicate that the mode of operation of the climate model seems to be as important as the interannual variability of the dust cloud by climate variations alone.
Nd and Pb isotope signatures of the clay‐size fraction of Labrador Sea sediments during the Holocene: Implications for the inception of the modern deep circulation pattern
Authors: Fagel N. , Hillaire‐Marcel C. , Humblet M. , Brasseur R. , Weis D. , Stevenson R.
Published: July 2004

Nd and Pb isotopes were measured on the fine fraction of one sediment core drilled off southern Greenland. This work aims to reconstruct the evolution of deep circulation patterns in the North Atlantic during the Holocene on the basis of sediment supply variations. For the last 12 kyr, three sources have contributed to the sediment mixture: the North American Shield, the Pan‐African and Variscan crusts, and the Mid‐Atlantic Ridge. Clay isotope signatures indicate two mixtures of sediment sources. The first mixture (12.2–6.5 ka) is composed of material derived from the North American shield and from a “young” crustal source. From 6.5 ka onward the mixture is characterized by a young crustal component and by a volcanic component characteristic of the Mid‐Atlantic Ridge. Since the significant decrease in proximal deglacial supplies, the evolution of the relative contributions of the sediment sources suggests major changes in the relative contributions of the deep water masses carried by the Western Boundary Undercurrent over the past 8.4 kyr. The progressive intensification of the Western Boundary Undercurrent was initially associated mainly with the transport of the Northeast Atlantic Deep Water mass until 6.5 ka and with the Denmark Strait Overflow Water thereafter. The establishment of the modern circulation at 3 ka suggests a reduced influence of the Denmark Strait Overflow Water, synchronous with the full appearance of the Labrador Seawater mass. Our isotopic data set emphasizes several changes in the relative contribution of the two major components of North Atlantic Deep Water throughout the Holocene.
Black box modeling of magnetospheric dynamics to forecast geomagnetic activity
Authors: Gholipour Ali , Lucas Caro , Araabi Babak N.
Published: July 2004

The Kp geomagnetic activity index is an important indicator of geomagnetic disturbances, which mark adverse space weather conditions affecting space missions and causing satellite anomalies. Therefore accurate Kp prediction is essential for warning and alert systems. A black box model, based on a recently developed locally linear neurofuzzy model, is proposed to reconstruct the highly nonlinear and complex dynamics of the magnetosphere. While most of the previous studies have investigated input‐output models of the solar wind–driven magnetosphere, this network is trained to use only nine previous observations of Kp time series to reconstruct the internal dynamics and to predict the forthcoming Kp values of the test years (from 1991 to 2000). The incremental learning algorithm initializes the model with an optimal linear least squares estimation and automatically increases the number of neurons in each epoch. The model is optimized for the number of neurons to avoid overfitting and to provide maximum generalization by considering the error index of validation sets during training. The obtained results, for example, RMS error of 0.84 and correlation factor of 0.807 between the predicted and observed values, are superior in comparison with previous studies. The rate of correct, missed, and false detections for related warning messages are also calculated and reported.
On the use of peak concentration arrival times for the inference of hydrogeological parameters
Authors: Bellin Alberto , Rubin Yoram
Published: July 2004

Aquifer characterization is subject to large uncertainty due to spatial variability of the hydrologic parameters on the one hand, coupled with data scarcity and measurement error on the other. Traditional characterization methods rely on direct measurements of the hydrologic parameters, which usually are quite few and with large distances in between. In recent years, attempts have been made to evaluate low‐cost, minimally invasive alternative sources of information that can be used to augment the direct measurements. This paper attempts to augment the data available for characterization by looking at tracer experiments. Specifically, we analyze the suitability of peak concentration arrival times to provide information useful for inference of geostatistical models of the conductivity. We found that the peak concentration arrival time is a good proxy for the advection‐dominated travel time and that it is particularly useful for inference through comparison with advection‐dominated, Lagrangian travel time moments when these models are expressed in terms of the geostatistical models of the conductivity. What makes the peak arrival time suitable for this is its limited sensitivity to pore‐scale dispersion at early travel times and its resistance to errors induced by infrequent sampling especially at early and late arrival times. This paper analyzes this concept through analysis of a synthetic case study as well as an analysis of field data collected during a forced‐gradient tracer test.