bluuebunny/crossref_metadata_2025 huggingface dataset:
Adsorption of benzotriazole on copper surfaces in a hydrochloric acid solution
Authors: Bastidas David M.
Published: May 2006

The adsorption of benzotriazole (BTA) on commercial copper surfaces in hydrochloric (HCl) acid concentrations from 1 × 10−3 to 5 × 10−1 M was investigated using gravimetric measurements. BTA in bulk solution was tested in concentrations from 1 × 10−5 to 1 × 10−1 M at temperatures from 298 to 328 K. The adsorption mechanism is discussed using the objective function (OF) and in terms of applicability of the conventional isotherm models. The best fit was obtained using the Frumkin equation. The projected molecular area of BTA was calculated to elucidate inhibitor orientation in the adsorption process. Copyright © 2006 John Wiley & Sons, Ltd.
Responses to anomalous data obtained from repeatable experiments in the laboratory
Authors: Lin Jer‐Yann
Published: May 2006

The purpose of this study was to investigate the possible responses to anomalous data obtained from experiments that are repeatable by carrying out additional or alternative experiments in the laboratory. Based on an analysis of responses from scientists to anomalous data taken from identification experiments on the Vinland Map, it was assumed that an additional response—uncertainty about interpretation of the data—should be considered in addition to the other eight responses reported by Chinn and Brewer 1998. It was also assumed that a process of responses containing more than one response is possible for a given subject who is responding to a given piece of anomalous datum in the laboratory. Both assumptions were verified by examining responses of undergraduates to anomalous data obtained from repeatable laboratory experiments. The results of this study show that there are nine categories of responses: ignoring; rejection; uncertainty of validity; uncertainty of interpretation; exclusion; abeyance; reinterpretation; peripheral conceptual change; and conceptual change. Moreover, two categories of processing, anomalous data–final response (A‐R process) and anomalous data–[mediators with/without intermediate responses]–final response (A‐M‐R process), are assessed in this study. It is suggested that science instructors could use the nine categories of responses to understand the learning characteristics of students, and also to use the A‐M‐R process to design suitable teaching strategies to arrive at meaningful learning. © 2006 Wiley Periodicals, Inc. J Res Sci Teach 44: 506–528, 2007
Acute Amebic Appendicitis
Authors: Guzmán‐Valdivia Gilberto
Published: May 2006

Introduction

Acute appendicitis of amebic origin is considered a rare cause of acute appendicitis.

Methods

The clinical notes for 4093 patients over the age of 16 who had undergone appendectomy were reviewed. Particular attention was paid to the histopathologic results, separating out those cases where trophozoites were seen in the appendix. These cases were considered to be of amebic origin.

Results

A total of 93 cases reported lesions suggestive of amebiasis (2.3%). This study analyzed 86 of these cases. Comparing the cases in this study against the cases of patients with acute appendicitis in general (excluding the cases of amebic origin), no differences were found in relation to the distribution or presentation according to sex or in the degree of inflammation of the appendix, the incidence of surgical wound infection, or general complications. By contrast, the study noted a statistically significant difference in the age at presentation: Acute appendicitis of amebic origin presents principally among those under 20 years of age and is accompanied by a higher frequency of fecal fistula (2.3%).

Conclusions

Acute appendicitis of amebic origin is not seen frequently, and in general it does not behave any differently from other cases of acute appendicitis, except in its earlier presentation and its greater incidence of fecal fistula. The condition is suspected clinically whenever a cecum of hard, “cardboard‐like” consistency is discovered.
Indications and Techniques of Extended Resection for Pancreatic Cancer
Authors: Nakao Akimasa , Takeda Shin , Inoue Soichiro , Nomoto Shuji , Kanazumi Naohito , Sugimoto Hiroyuki , Fujii Tsutomu
Published: May 2006

Introduction

The resectability rate and postoperative survival rate for pancreatic carcinoma are poor. Aggressive resection including vascular resection and extended lymphadenectomy represent one strategy for improving survival. This study was carried out to clarify the indications for extended resection, especially vascular resection, for pancreatic carcinoma.

Methods

From July 1981 to March 2005, we performed curative resection in 289 of 443 patients with pancreatic carcinoma in our department (65.2%). Vascular resection was performed in 201 (69.5%) patients and portal vein resection without arterial resection in 186 patients. Combined portal and arterial resection was performed in 14 patients and arterial resection without portal vein resection in 1. Extended lymphadenectomy including paraaortic lymph nodes was done. The postoperative survival rate was stratified according to operative and pathology findings.

Results

Operative mortality (any death within 30 days after surgery) occurred in 11 of the 289 curative resection patients (3.8%), including 1 of 88 patients without vascular resection (1.1%), 5 of 186 portal vein resection patients without arterial resection (2.7%), and 5 of 14 (35.7%) arterial resection patients undergoing portal vein arterial resection as well. Most patients who survived for 2 to 3 years had carcinoma‐free surgical margins.

Conclusions

The most important indication for vascular resection in patients with pancreatic cancer is the ability to obtain cancer‐free surgical margins. Otherwise, vascular resection is contraindicated. Extended lymphadenectomy may be not of benefit.
Dry season diets of sympatric ungulates in lowland Nepal: competition and facilitation in alluvial tall grasslands
Authors: Wegge Per , Shrestha Anil K. , Moe Stein R.
Published: May 2006

Based on microhistological analyses of faecal material, we compared the early dry season diets of greater one‐horned rhinoceros Rhinoceros unicornis, swamp deer Cervus duvauceli and hog deer Axis porcinus, which inhabit the same alluvial grassland habitat complex in lowland Nepal. Their diets were quite similar, both at the forage category level and within subcategories of graminoids and woody plants. Early successional tall grasses, especially Saccharum spontaneum, were the dominant food of all three species, underlining the key role of the threatened alluvial floodplains in large mammal conservation in South Asia. The two deer species ate significantly more graminoids (>66.5%) than did rhino (45.5%), and although they did not differ in proportions of graminoids, swamp deer ate significantly more late successional tall grasses (Narenga porphyrocoma and Themeda spp.) and short grasses (mainly Imperata cylindrica) than hog deer. The two deer consumed almost equal proportions of woody browse (ca. 10%), significantly less than that of rhino (33.0%). The prediction of the Jarman–Bell hypothesis, that large‐bodied herbivores are less selective and subsist on lower quality graminoids than smaller ruminants, was not supported by the data. Based on this and previous studies in the same area we propose a conceptual model where the larger megaherbivores (rhino and elephant Elephas maximus) facilitate the smaller swamp deer and hog deer during the monsoonal growing season, while the smaller and more selective deer species outcompete the larger during the dry season when food is more limited. Owing to the all‐year sprouting ability of S. spontaneum, facilitation may occur also in the dry season with low numbers of megaherbivores, thus accentuating competitive exclusion at higher deer densities.
New linker proteins in phycobilisomes isolated from the cyanobacterium Gloeobacter violaceus PCC 7421
Authors: Koyama Kohei , Tsuchiya Tohru , Akimoto Seiji , Yokono Makio , Miyashita Hideaki , Mimuro Mamoru
Published: May 2006

Two new linker proteins were identified by peptide mass fingerprinting in phycobilisomes isolated from the cyanobacterium Gloeobacter violaceus PCC 7421. The proteins were products of glr1262 and glr2806. Three tandem phycocyanin linker motifs similar to CpcC were present in each. The glr1262 product most probably functions as a rod linker connecting phycoerythrin and phycocyanin, while the glr2806 product may function as a rod‐core linker. We have designated these two proteins CpeG and CpcJ, respectively. The morphology of phycobilisomes in G. violaceus has been reported to be a bundle‐like shape with six rods, consistent with the proposed functions of these linkers.
Properties of the prolyl oligopeptidase homologue from Pyrococcus furiosus
Authors: Juhász Tünde , Szeltner Zoltán , Polgár László
Published: May 2006

Prolyl oligopeptidase (POP), the paradigm of a serine peptidase family, hydrolyses peptides, but not proteins. The thermophilic POP from Pyrococcus furiosus (Pfu) appeared to be an exception, since it hydrolysed large proteins. Here we demonstrate that the Pfu POP does not display appreciable activity against azocasein. The autolysis observed earlier was an artefact. We have also found that the pH‐rate profile is different from that of the mammalian enzyme and the low pK
a extracted from the curve represents the ionization of the catalytic histidine. We conclude that some oligopeptidases may be true endopeptidases, cleaving at disordered segments of proteins, but with very low efficacy.
Elevated phenylalanine levels interfere with neurite outgrowth stimulated by the neuronal cell adhesion molecule L1 in vitro
Authors: Hartwig Christine , Gal Andreas , Santer Rene , Ullrich Kurt , Finckh Ulrich , Kreienkamp Hans-Jürgen
Published: May 2006

Elevated levels of phenylalanine (Phe) as observed in patients with phenylketonuria interfere with proper neuronal development, leading to severe psychomotor deficits and mental retardation. We have analyzed the effects of Phe on neurite outgrowth in vitro. When expressed in fibroblasts, the neuronal cell adhesion molecules L1 and plexin B3 strongly increase the length of neurites emanating from cerebellar neurons in co‐culture experiments. Elevated Phe blocks L1‐mediated, but not plexin B3‐mediated outgrowth, whereas tyrosine is ineffective. Elevated Phe also interferes with aggregation of fibroblasts overexpressing L1, suggesting that the pathological effect of elevated Phe occurs by interfering with L1‐mediated cell adhesion.
An essential role for salicylic acid in AtMYB30‐mediated control of the hypersensitive cell death program in Arabidopsis
Authors: Raffaele Sylvain , Rivas Susana , Roby Dominique
Published: May 2006

Salicylic acid (SA) plays a central role in resistance and defense induction in response to pathogen attack, but its role in the activation of the hypersensitive response (HR), a form of programmed cell death associated with resistance of plants, remains to be elucidated. AtMYB30, a R2R3‐MYB transcriptional factor which acts as a positive regulator of the HR, is a good model for studying the role of SA in programmed cell death. Here, we demonstrate that AtMYB30 expression in response to an HR‐inducing bacterial pathogen is dependent on SA accumulation, but NPR1‐independent. Alterations of AtMYB30 expression (overexpression, depletion by antisense strategy, T‐DNA insertion mutant) modulate SA levels and SA‐associated gene expression. Additionally, mutants or transgenic lines altered in SA accumulation (nahG, sid1, sid2), but not those affected in SA signalling (npr1), abolish the accelerated cell death phenotype conferred by over‐expression of AtMYB30. These results suggest that AtMYB30 is involved in an amplification loop or signalling cascade that modulates SA synthesis, which in turn modulates cell death.
Differences in the regulation of microtubule stability by the pro‐rich region variants of microtubule‐associated protein 4
Authors: Hasan Mohammad Rubayet , Jin Mingyue , Matsushima Kazuyuki , Miyamoto Shigeaki , Kotani Susumu , Nakagawa Hiroyuki
Published: May 2006

We have recently reported a neural variant of microtubule‐associated protein 4 with a short pro‐rich region (MAP4‐SP). Here, we show that the neural MAP4 has reduced microtubule‐stabilizing activity, compared to the ubiquitous MAP4 with a long pro‐rich region (MAP4‐LP), both in vitro and in vivo. Fluorescence recovery after photobleaching analyses revealed that the interaction of MAP4‐SP with the microtubules is very rapid, with a half‐time of fluorescence recovery of 7 ± 2.36 s, compared to 19.5 ± 3.03 s in case of MAP4‐LP. The dynamic interaction of MAP4‐SP with microtubules in neural cells may contribute to the dynamic behaviors of extending neurites.
Neuroprotective effect of etomidate on functional recovery in experimental spinal cord injury
Authors: Cayli Suleyman R. , Ates Ozkan , Karadag Nese , Altinoz Eyup , Yucel Neslihan , Yologlu Saim , Kocak Ayhan , Cakir Celal Ozbek
Published: May 2006

Objective

Primary impact to the spinal cord causes rapid oxidative stress after injury. To protect neural tissue, it is important to prevent secondary pathophysiological mechanisms. Etomidate, a strong antiexcitotoxic agent, stimulates the gamma aminobutyric acid (GABA) receptors. The purpose of this study was to investigate neurobehavioral and histological recovery and to evaluate the biochemical responses to treatment of experimental spinal cord injury (SCI) in rats with etomidate or methylprednisolone (MP) or both etomidate and MP.

Material and methods

Seventy‐two rats were randomly allocated into six groups: a control group (laminectomy alone), a trauma group (laminectomy + trauma), a methylprednisolone group (30 mg/kg MP), an etomidate group (2 mg/kg), a methylprednisolone and etomidate combined treatment group (30 mg/kg MP and 2 mg/kg etomidate) and a vehicle group. Six rats from each group were killed at the 24th hour after the injury. Malondialdehyde, glutathione, nitric oxide and xanthine oxidase levels were measured. Neurological functions of the remaining rats were recorded weekly. Six weeks after injury, all of those rats were killed for histopathological assesssment.

Results

Etomidate treatment revealed similar neurobehavioral and histopathological recovery to MP treatment 6 weeks after injury. Combined treatment did not provide additional neuroprotection.

Conclusion

Etomidate treatment immediately after spinal cord injury has similar neuroprotection to MP. In spite of different neuroprotection mechanisms, combined treatment with MP and etomidate does not provide extra protection.
General linear methods
Authors: Butcher J. C.
Published: May 2006

General linear methods, as multistage multivalue methods, are the natural generalizations of linear multistep and Runge-Kutta methods. This survey contains a discussion of the traditional methods and a motivation for the general linear type of generalization. The new methods are introduced in terms of their formulation and the basic properties of consistency, stability and convergence. The order of general linear methods has to be looked at from a new point of view and it is shown how to use an algebraic structure (equivalent to B-series) to express conditions for a given order. Linear and non-linear stability for the new methods brings the theories for the classical methods into a comprehensive formulation and known results are outlined. Recently a number of subfamilies have been introduced and some of these are considered in detail. This applies in particular to methods with the property known as ‘inherent Runge-Kutta stability’. These seem to have prospects of yielding useful and efficient methods, and some progress towards their practical implementation is outlined. Finally, the relationship between stability functions and order of methods is discussed in a setting wide enough to include general linear methods as well as multiderivative methods, such as Obreshkov methods. The classical barriers due to Ehle, Daniel-Moore and Dahlquist (second barrier) all fit into a common pattern and these are explored in a general setting.
Modern statistical estimation via oracle inequalities
Authors: Candès Emmanuel J.
Published: May 2006

A number of fundamental results in modern statistical theory involve thresholding estimators. This survey paper aims at reconstructing the history of how thresholding rules came to be popular in statistics and describing, in a not overly technical way, the domain of their application. Two notions play a fundamental role in our narrative: sparsity and oracle inequalities. Sparsity is a property of the object to estimate, which seems to be characteristic of many modern problems, in statistics as well as applied mathematics and theoretical computer science, to name a few. ‘Oracle inequalities’ are a powerful decision-theoretic tool which has served to understand the optimality of thresholding rules, but which has many other potential applications, some of which we will discuss.

Our story is also the story of the dialogue between statistics and applied harmonic analysis. Starting with the work of Wiener, we will see that certain representations emerge as being optimal for estimation. A leitmotif throughout our exposition is that efficient representations lead to efficient estimation.
Numerical linear algebra in data mining
Authors: Eldén Lars
Published: May 2006

Ideas and algorithms from numerical linear algebra are important in several areas of data mining. We give an overview of linear algebra methods in text mining (information retrieval), pattern recognition (classification of handwritten digits), and PageRank computations for web search engines. The emphasis is on rank reduction as a method of extracting information from a data matrix, low-rank approximation of matrices using the singular value decomposition and clustering, and on eigenvalue methods for network analysis.
Numerical modelling of ocean circulation
Authors: Higdon Robert L.
Published: May 2006

Computational simulations of ocean circulation rely on the numerical solution of partial differential equations of fluid dynamics, as applied to a relatively thin layer of stratified fluid on a rotating globe. This paper describes some of the physical and mathematical properties of the solutions being sought, some of the issues that are encountered when the governing equations are solved numerically, and some of the numerical methods that are being used in this area.
Kernel techniques: From machine learning to meshless methods
Authors: Schaback Robert , Wendland Holger
Published: May 2006

Kernels are valuable tools in various fields of numerical analysis, including approximation, interpolation, meshless methods for solving partial differential equations, neural networks, and machine learning. This contribution explains why and how kernels are applied in these disciplines. It uncovers the links between them, in so far as they are related to kernel techniques. It addresses non-expert readers and focuses on practical guidelines for using kernels in applications.
Modest benefits of adjuvant chemotherapy in hormone receptor-positive breast cancer
Authors: Svahn Tiffany H. , Carlson Robert W.
Published: May 2006

The benefits of adjuvant chemotherapy, endocrine therapy, and trastuzumab therapy are well-established in patients with early breast cancer. Further, there are patient and tumor characteristics that can assist in predicting which patients are more likely to benefit from specific adjuvant therapies. For example, patients whose tumors express estrogen and/or progesterone receptors (ER/PR) derive significant benefit from adjuvant endocrine therapy, whereas those whose tumors do not express these receptors derive very little or no benefit from endocrine therapy [1]. Patients whose tumors overexpress HER2 experience profound benefits from treatment with adjuvant trastuzumab [2,3]. We have recently begun to understand that ER/PR-positive breast cancer also responds differently to chemotherapy than its hormone receptor-negative counterpart. This is not, however, entirely new information. As early as 1978, it was retrospectively observed that ER-positive metastatic breast cancer had lower response rates to a variety of older chemotherapy regimens than did ER-negative disease [4].
The consequences of agricultural trade liberalization for developing countries: distinguishing between genuine benefits and false hopes
Authors: BUREAU JEAN-CHRISTOPHE , JEAN SÉBASTIEN , MATTHEWS ALAN
Published: May 2006

Recent analyses suggest that the impact of agricultural trade liberalization on developing countries will be very uneven. The Doha Round focuses on tariff issues, but some developing countries currently have practically duty-free access to European and North American markets under preferential regimes. Multilateral liberalization will erode the benefits of these preferences, which are presently rather well utilized in the agricultural sector. While South American and East Asian countries should benefit from an agricultural agreement, African and Caribbean countries are unlikely to do so. The main obstacles to the exports of the sub-Saharan African and Least Developed Countries appear to be in the non-tariff area (sanitary, phytosanitary standards), which increasingly originate from the private sector and are not dealt with under the Doha framework (traceability requirements, etc.). An agreement in Doha is unlikely to solve these problems and open large markets for the poorest countries. While this is not an argument to give up multilateral liberalization, a more specific and differentiated treatment should be considered in WTO rules, and corrective measures should be implemented.
El mess in TELMEX: a comment on Mexico-measures affecting telecommunications services
Authors: NEVEN DAMIEN J. , MAVROIDIS PETROS C.
Published: May 2006

This paper reviews the panel report on Mexico-Measures A.ecting Telecommunication Services. The panel considered claims by the United States (US) that Mexico acted inconsistently with its obligations with respect to the liberalization of the market for telecommunication services. It is the .rst panel to consider solely the rules agreed in the General Agreement on Trade in Services (GATS). It is also the .rst panel to deal with telecommunication services and its complex layers of legislation, in particular the rules agreed in the Telecommunications Reference Paper (TRP)onpro-competitive regulatory principles. Viewed fromthis perspective, this report is because of its potential precedence value, of particular signi.cance.
Perturbation of the Izmit earthquake aftershock decaying activity following the 1999 Mw 7.2 Düzce, Turkey, earthquake
Authors: Daniel Guillaume , Marsan David , Bouchon Michel
Published: May 2006

Triggering and quiescence patterns of seismicity in western Turkey, following the occurrence of the 12 November 1999 Mw 7.2 Düzce earthquake are investigated. The changes in seismicity rate are analyzed along the North Anatolian Fault segments that had ruptured 3 months earlier during the 17 August 1999 Mw 7.4 Izmit earthquake. Detection of triggering and quiescence is done by comparing the seismicity rate that would be expected if the Düzce earthquake had not happened to the actual observed rate. The expected rates are estimated by extrapolating the preexisting seismicity pattern, using two complementary models: a simple Omori‐Utsu's law and the ETAS model. Fault segments located to the east of the Izmit epicenter show a mild case of quiescence following the Düzce earthquake. These segments had previously experienced an anomalous triggering episode in the 5 days preceding the Düzce earthquake, correlated with the occurrence of two strong (Mw ≥ 5) Izmit aftershocks. However, it is not clear whether this observed quiescence is real or spurious, as it coincides with a local reconfiguration of the seismological network: a temporary increase of 0.1 to 0.15 in completeness magnitude would be enough to explain this apparent deactivation. Fault segments located to the west of the Izmit epicenter exhibit triggering of seismicity following the Düzce earthquake. This observed triggering is mostly restricted to a cluster of events located in the geothermal area of Yalova. The increase of seismicity rate is delayed by 18 hours after the waves travelling from the Düzce rupture had hit this zone. Our analysis suggests that this 15‐day‐long reactivation can be explained by a short‐lived perturbation, the local seismic activity then sustaining itself for the remaining 15 days. We argue that this particular behavior is likely to correspond to a case of dynamic triggering. By the end of year 1999, the Yalova cluster shows a significant quiescence that lasted for several months; this shutting down does not coincide with the occurrence of any local earthquake that would be large enough to stress shadow this area, suggesting an aseismic cause to this pattern. These results highlight the fact that (1) seismicity triggered by a major earthquake is not restricted to areas loaded by static stress and (2) that seismic activity associated with geothermal geological settings is highly sensitive to stress perturbations, but also to aseismic processes, that can both delay reactivation and cause this activity to suddenly decrease.
Quantifying nutrient supply to the Southern Ocean
Authors: Pollard Raymond , Tréguer Paul , Read Jane
Published: May 2006

Using nutrient concentrations on neutral density surfaces in the Southern Ocean and climatological winds, both of which are fairly well constrained, we have estimated the long‐term average of net export from the upper ocean (i.e., the net supply of nutrients in Circumpolar Deep Water and Antarctic Intermediate Water to the surface layer) over the whole of the Southern Ocean south of the wind stress maximum at an average latitude of 50°S. We calculate net new production (equivalent to export production) values of 51 ± 3 Tmol Si yr−1 and 14 ± 3 Tmol N yr−1. The latter is equivalent to 1.1 ± 0.2 Pg C yr−1 when scaled with the Redfield ratio of C to N. These values are in good agreement with recent observational and modeling estimates and are reasonably in line with inverse model calculations. Interpolating the high‐quality data from meridional World Ocean Circulation Experiment sections onto the neutral density surfaces revealed remarkable constancy of nutrient concentrations at all longitudes and depths below about 340 ± 100 m, which we call the surface‐influenced depth. This indicates that isopycnic stirring by eddies in the Southern Ocean is efficient at homogenizing nutrient concentrations and removing any signature of remineralization. The large depth of the surface‐influenced depth, over twice the winter mixed layer depth, also indicates that eddies must be responsible for transferring nutrient deficits resulting from drawdown in the surface layer across the pycnocline to several hundred meters deep.
Measurements of ambient ammonia using a tunable diode laser absorption spectrometer: Characteristics of ambient ammonia emissions in an urban area of New York City
Authors: Li Yongquan , Schwab James J. , Demerjian Kenneth L.
Published: May 2006

A tunable diode laser absorption spectrometer (TDLAS) was deployed during the PMTACS‐NY Supersite winter 2004 intensive field campaign at Queens College in New York City to measure the ambient gaseous ammonia. For the characterization of ammonia emissions from the mobile sources, a LI‐7000 CO2/H2O analyzer was also collocated with the TDLAS to measure ambient CO2 and H2O vapor. The field measurements and laboratory calibration with certified ammonia standard have been used to evaluate the performance of the TDLAS system. High time resolved TDLAS ambient ammonia measurements performed at Queens College from 10 January to 6 February showed high variability, with NH3 concentrations ranging from below the detection limit (0.1 ppb) to maxima of 197.4 ppb and a mean value of 0.8 ppb over the entire campaign. Many high‐frequency NH3 spikes spanning over a less than 1‐min duration were observed during the high traffic periods. The occurrence of the NH3 spikes was closely correlated with observed CO2 spikes, a good marker of traffic exhaust. This correlation yielded an NH3 emission ratio of 0.12 ppbv/ppmv, which can be used to estimate an NH3 emission factor of 35.5 mg/km. The [NH3]/[CO2] ratios over the entire field study was also obtained and added into the best NH3 emission estimates. On a snowy day, no obvious drop of NH3 and CO2 concentrations was measured as the ambient H2O vapor increased. The observed dramatic decrease in the ambient NH3 and CO2 concentrations on a rainy day resulted from a quick air mass switch. Two similar bimodal diurnal patterns associated with the rush hour traffic were observed during school holidays and school days of Queens College, New York. More NH3 emissions from cold start vehicles might contribute to a higher peak in the late afternoon hours. Such observations suggest that the NH3 emissions from the traffic exhaust could be a major source of the ambient NH3 in urban areas.
Maximum entropy spectral analysis of climatic time series revisited: Assessing the statistical significance of estimated spectral peaks
Authors: Pardo‐Igúzquiza Eulogio , Rodríguez‐Tovar Francisco J.
Published: May 2006

One of the most often used methods in the spectral analysis of climatic time series is the parametric method of maximum entropy based on an autoregressive model. The method of maximum entropy is particularly appealing because of its high resolution and its good performance with short time series. Its main drawback is that the statistical significance of the spectral peaks is difficult to assess; consequently, there is a risk of accepting spurious peaks as having a physical origin. We propose to use a computer intensive method, the permutation test, for assessing the statistical significance of the spectral peaks, showing its implementation and the results using simulated and real data. With the simulated data we illustrate the applicability to a short time series but with rich signal content, while with the time series of the Southern Oscillation Index (SOI) we illustrate how it may be used in the estimation of the spectrogram.
Relationship between air and soil temperature trends and periodicities in the permafrost regions of Russia
Authors: Chudinova Svetlana M. , Frauenfeld Oliver W. , Barry Roger G. , Zhang Tingjun , Sorokovikov Victor A.
Published: May 2006

Soil temperature is an important indicator of frozen ground status, driven at least partly by air temperature variability. In this study we apply singular spectrum analysis (SSA) to detect trends and oscillations in annual and seasonal time series of surface air temperature (SAT) and soil temperature (ST). We investigate soil temperatures at depths of 0.4, 1.6, and 3.2 m for five permafrost‐occupied regions in Russia. We use SAT data for 1902–1995 and ST data for 1960–1990. The trends show an increase in annual SAT and ST from the end of the 1960s across all five regions, and this warming exceeds that of the preceding period in the Central Siberian Plateau and Transbaikalia. Oscillations in annual SAT and ST time series are coincident in the West Siberian Plain (7.7 year period) and in the western Central Siberian Plateau and Transbaikalia (2.7 year period). In general, on a seasonal basis, 2–3 year oscillations in ST and SAT are coincident during winter, spring, and autumn across the regions and are also evident in the annual ST time series in the Central Siberian Plateau and Transbaikalia. We also find a decadal oscillation (9.8 year period), which is coincident for winter SAT and ST, over the western Central Siberian Plateau only. Although summer SAT and ST oscillations (5–8 year periods) are coincident for all investigated territories (except to the east of the Lena River), in the annual ST time series they are identified only for the West Siberian Plain. We document the degree to which SAT controls ST in each region and explore the causative factors for some of the dominant periods. The maximum effect of SAT increases on permafrost may be observed in the Central Siberian Plateau and Transbaikalia, while elsewhere the observed ST increases do not threaten permafrost areas.
Decomposing CO2 fluxes measured over a mixed ecosystem at a tall tower and extending to a region: A case study
Authors: Wang Weiguo , Davis Kenneth J. , Cook Bruce D. , Butler Martha P. , Ricciuto Daniel M.
Published: May 2006

CO2 fluxes for six stand types are inferred by decomposing eddy‐covariance (EC) fluxes measured at a 447‐m tower using footprint models and ecosystem models in a case study. The functional parameters in the ecosystem models are estimated for each stand type utilizing temporal EC flux series. The results show differences in terms of the functional parameters and fluxes among the different stand types that are consistent with general expectations for the respective stand types. The fluxes, in addition to measurements at two nearby short towers, are used for flux aggregation in the region. Comparisons suggest that it is critical for flux aggregation to distinguish the wetland from the upland. A distinction among three upland forests and between forested and lowland wetlands could be important, too. The difference in aggregated values of net ecosystem‐atmospheric exchange of CO2 with the watershed function classification scheme and with the stand‐type level classification scheme can reach about 250 gC m−2 season−1 over the entire growing season. Analyses suggest that the six‐stand classification scheme still does not capture all the variability in stand characteristics relevant to CO2 exchange. In addition, the varying fluxes for the same stand type with location in the region challenge the widely used land‐cover‐based ecosystem classification scheme. It is improper to use EC measurements at any single tower to approximate CO2 fluxes in the region. Implications may help identify key ecosystem types and design more measurements in the region. Limitations and future efforts are discussed.
Flow resistance dynamics in step‐pool stream channels: 1. Large woody debris and controls on total resistance
Authors: Wilcox Andrew C. , Wohl Ellen E.
Published: May 2006

Flow resistance dynamics in step‐pool channels were investigated through physical modeling using a laboratory flume. Variables contributing to flow resistance in step‐pool channels were manipulated in order to measure the effects of various large woody debris (LWD) configurations, steps, grains, discharge, and slope on total flow resistance. This entailed nearly 400 flume runs, organized into a series of factorial experiments. Factorial analyses of variance indicated significant two‐way and three‐way interaction effects between steps, grains, and LWD, illustrating the complexity of flow resistance in these channels. Interactions between steps and LWD resulted in substantially greater flow resistance for steps with LWD than for steps lacking LWD. LWD position contributed to these interactions, whereby LWD pieces located near the lip of steps, analogous to step‐forming debris in natural channels, increased the effective height of steps and created substantially higher flow resistance than pieces located farther upstream on step treads. Step geometry and LWD density and orientation also had highly significant effects on flow resistance. Flow resistance dynamics and the resistance effect of bed roughness configurations were strongly discharge‐dependent; discharge had both highly significant main effects on resistance and highly significant interactions with all other variables.
Recent glacial recession in the Rwenzori Mountains of East Africa due to rising air temperature
Authors: Taylor Richard G. , Mileham Lucinda , Tindimugaya Callist , Majugu Abushen , Muwanga Andrew , Nakileza Bob
Published: May 2006

Based on field surveys and analyses of optical spaceborne images (LandSat5, LandSat7), we report recent decline in the areal extent of glaciers in the Rwenzori Mountains of East Africa from 2.01 ± 0.56 km2 in 1987 to 0.96 ± 0.34 km2 in 2003. The spatially uniform loss of glacial cover at lower elevations together with meteorological trends derived from both station and reanalysis data, indicate that increased air temperature is the main driver. Clear trends toward increased air temperatures over the last four decades of ∼0.5°C per decade exist without significant changes in annual precipitation. Extrapolation of trends in glacial recession since 1906 suggests that glaciers in the Rwenzori Mountains will disappear within the next two decades.
Reconstruction of early spring temperature for central Japan from the tree‐ring widths of Hinoki cypress and its verification by other proxy records
Authors: Yonenobu Hitoshi , Eckstein Dieter
Published: May 2006

We describe the results of a dendroclimatic study in central Japan using ring width data from living trees of Hinoki cypress. February–April temperatures were reconstructed for the period AD 1719–1961. This reconstruction, from which five cooling events were determined for the late Little Ice Age, was validated against other climate proxies. There is a reasonable agreement with cold periods previously estimated from documentary records in Japan and China. A notably good agreement is also found for a dendroclimatic reconstruction for Korea, suggesting that the annual activity of the winter monsoon in the western Pacific Rim persisted longer in the 19th century than at present. Records of prolonged famines and unusual climatic phenomena support the reconstruction of the cold periods in the 1780s, 1810s and 1830s. It is thus revealed that the Hinoki chronology has enough potential to reconstruct the climatic variability further into the past.
Changes in vascular reactivity following administration of isoproterenol for 1 week: a role for endothelial modulation
Authors: Davel Ana Paula C , Kawamoto Elisa Mitiko , Scavone Cristoforo , Vassallo Dalton V , Rossoni Luciana V
Published: May 2006

The aim of this study was to assess the effects of treatment with isoproterenol (ISO, 0.3 mg kg−1 day−1, s.c.) for 7 days on the vascular reactivity of rat‐isolated aortic rings. Additionally, potential mechanisms underlying the changes that involved the endothelial modulation of contractility were investigated.

Treatment with ISO induced cardiac hypertrophy without changes in haemodynamic parameters. Aortic rings from ISO‐treated rats showed an increase in the contraction response to phenylephrine (PHE) and serotonin, but did not change relaxations produced by acetylcholine or isoproterenol. Removal of the endothelium increased the responses to PHE in both groups. However, this procedure was less effective in ISO‐treated as compared with control rats. Endothelial cell removal abolished the increase in the response to PHE in ISO‐treated rats. The presence of Nω‐nitro‐L‐arginine methyl ester shifted the concentration–response curve to PHE to the left in both groups of rats. However, this effect was more pronounced in the ISO group. In addition, aminoguanidine (50 μM) potentiated the actions of PHE only in the ISO group. ISO treatment increased nitric oxide synthase (NOS) activity and neuronal NOS and endothelial NOS protein expression in the aorta.

Neither losartan (10 μM) nor indomethacin (10 μM) abolished the effects of ISO on the actions of PHE. Superoxide dismutase (SOD, 150 U ml−1) and L‐arginine (5 mM), but neither catalase (300 U ml−1) nor apocynin (100 μM), blocked the effect of ISO treatment. In addition, we observed an increase in superoxide anion levels as measured by ethidium bromide fluorescence and of copper and zinc superoxide dismutase protein expression in ISO‐treated rats.

In conclusion, our data suggest that ISO treatment alters the endothelial cell‐mediated modulation of the contraction to PHE in rat aorta. The increased maximal response of PHE seems to be due to an increase in superoxide anion generation, which inactivates some of the basal NO produced and counteracts NO‐mediated negative modulation even in the presence of high NO production and antioxidant defence.

British Journal of Pharmacology (2006) 148, 629–639. doi:10.1038/sj.bjp.0706749
Characterization and effects on cAMP accumulation of adrenomedullin and calcitonin gene‐related peptide (CGRP) receptors in dissociated rat spinal cord cell culture
Authors: Takhshid Mohammad A , Poyner David R , Chabot Jean‐Guy , Fournier Alain , Ma Weiya , Zheng Wen‐Hua , Owji Ali A , Quirion Remi
Published: May 2006

Adrenomedullin (AM) and calcitonin gene‐related peptide (CGRP) have structural similarities, interact with each others receptors (calcitonin receptor‐like receptor (CLR)/receptor‐activity‐modifying proteins (RAMPs)) and show overlapping biological activities. AM and CGRP receptors are chiefly coupled to cAMP production. In this study, a method of primary dissociated cell culture was used to investigate the presence of AM and CGRP receptors and their effects on cAMP production in embryonic spinal cord cells.

Both neuronal and non‐neuronal CLR immunopositive cells were present in our model.

High affinity, specific [125I]‐AM binding sites (Kd 79±9 pM and Bmax 571±34 fmol mg−1 protein) were more abundant than specific [125I]‐CGRP binding sites (Kd 12±0.7 pM and Bmax 32±2 fmol mg−1 protein) in embryonic spinal cord cells.

Specific [125I]‐AM binding was competed by related molecules with a ligand selectivity profile of rAM>hAM22–52>rCGRPα>CGRP8–37≫[r‐(r*,s*)]‐N‐[2‐[[5‐amino‐1‐[[4‐(4‐pyridinyl)‐1‐piperazinyl]carbonyl]pentyl]amino]‐1‐[(3,5‐dibromo‐4‐hydroxyphenyl)methyl]‐2‐oxoethyl]‐4‐(1,4‐dihydro‐2‐oxo‐3(2H)‐quinazolinyl)‐,1‐piperidinecarboxamide (BIBN4096BS).

Specific [125I]‐CGRP binding was competed by rCGRPα>rAMCGRP8–37BIBN4096BS>hAM22–52.

Cellular levels of cAMP were increased by AM (pEC50 10.2±0.2) and less potently by rCGRPα (pEC50 8.9±0.4). rCGRPα‐induced cAMP accumulation was effectively inhibited by CGRP8–37 (pA2 7.63±0.44) and hAM22–52 (pA2 6.18±0.21) while AM‐stimulation of cAMP levels was inhibited by CGRP8–37 (pA2 7.41±0.15) and AM22–52 (pA2 7.26±0.18). BIBN4096BS only antagonized the effects of CGRP (pA2 8.40±0.30) on cAMP accumulation.

These pharmacological profiles suggest that effects of CGRP are mediated by the CGRP1 (CLR/RAMP1) receptor in our model while those of AM are related to the activation of the AM1 (CLR/RAMP2) receptor subtype.

British Journal of Pharmacology (2006) 148, 459–468. doi:10.1038/sj.bjp.0706750
Hypothalamic neuropeptide Y (NPY) and the attenuation of hyperphagia in streptozotocin diabetic rats treated with dopamine D1/D2 agonists
Authors: Kuo Dong‐Yih
Published: May 2006

Dopamine is an appetite suppressant, while neuropeptide Y (NPY), an appetite stimulant in the brain, is reported to be involved in anorectic action induced by a combined administration of D1/D2 agonists in normal rats. In diabetic rats, however, these factors have not been studied.

Rats (including normal, diabetic and insulin‐treated diabetic rats) were given daily injections of saline or D1/D2 agonists for 6 days. Changes in food intake and hypothalamic NPY content of these rats were assessed and compared.

The D1/D2 agonist‐induced anorectic responses were altered in diabetic rats compared to normal rats treated similarly. Both the anorectic response on the first day of dosing and the tolerant response on the subsequent days were attenuated.

This alteration was independent of the neuroendocrine disturbance on feeding behavior since the basic pattern of food intake during the time course of a 24‐h day/night cycle was similar in normal and diabetic rats; the decrease of food intake following drug treatment was only shown at the initial interval of 0–6 h in both groups of rats.

However, this alteration coincided with changes in NPY content following D1/D2 coadministration. The replacement of insulin in diabetic rats could normalize both NPY content and D1/D2 agonist‐induced anorexia.

It is demonstrated that the response of D1/D2 agonist‐induced appetite suppression is attenuated in diabetic rats compared to normal rats and that elevated hypothalamic NPY content may contribute to this alteration.

British Journal of Pharmacology (2006) 148, 640–647. doi:10.1038/sj.bjp.0706754
Cholesteryl butyrate solid lipid nanoparticles inhibit adhesion of human neutrophils to endothelial cells
Authors: Dianzani Chiara , Cavalli Roberta , Zara Gian Paolo , Gallicchio Margherita , Lombardi Grazia , Gasco Maria Rosa , Panzanelli Patrizia , Fantozzi Roberto
Published: May 2006

Adhesion of polymorphonuclear cells (PMNs) to vascular endothelial cells (EC) is a critical step in recruitment and infiltration of leukocytes into tissues during inflammation. High doses of butyric acid have been shown to ameliorate inflammation in inflammatory bowel diseases (IBD). Cholesteryl‐butyrate solid lipid nanoparticles (chol‐but SLN) as prodrug are a possible delivery system for butyric acid.

Sodium butyrate or chol‐but SLN were coincubated with human PMNs and human umbilical vein EC (HUVEC); adhesion was quantified by computerized microimaging fluorescence analysis. Both chol‐but SLN and sodium butyrate displayed antiadhesive effects on FMLP‐ and IL‐1β‐stimulated cells in a concentration–response curve (10−8–10−5 M), but chol‐but SLN were in all cases more active. Moreover, chol‐but SLN inhibited FMLP‐induced adhesion of PMNs to FCS‐coated plastic wells, thus showing a direct effect on PMNs, while sodium butyrate had little effect. Confocal microscopy showed that fluorescent SLN entered PMNs and HUVEC after 10 min incubation. Chol‐but SLN acted either on activated PMN or HUVEC.

Chol‐but SLN inhibited O2−· production and myeloperoxidase release by PMNs evoked by FMLP, in a dose‐dependent, but not time‐dependent, manner and were more active than sodium butyrate.

In conclusion, in all tests chol‐but SLN were more active than sodium butyrate. Thus, chol‐but SLN might be a valid alternative to sodium butyrate in the anti‐inflammatory therapy of ulcerative colitis, avoiding complications related to the administration of sodium butyrate.

British Journal of Pharmacology (2006) 148, 648–656. doi:10.1038/sj.bjp.0706761
Local regulation of skin blood flow during cooling involving presynaptic P2 purinoceptors in rats
Authors: Koganezawa Tadachika , Ishikawa Tomohisa , Fujita Yukiyoshi , Yamashita Tomonari , Tajima Takako , Honda Masaki , Nakayama Koichi
Published: May 2006

This study investigated a local effect of cooling on the plantar skin blood flow (PSBF) of tetrodotoxin‐treated rats by laser‐Doppler flowmetry.

When the air temperature around the left foot was locally cooled from 25 to 10°C, the PSBF of the left foot decreased.

The response was inhibited by theα‐adrenoceptor antagonist phentolamine, theα1‐adrenoceptor antagonist bunazosin, theα2‐adrenoceptor antagonist RS79948, and bretylium and guanethidine that inhibit noradrenaline release from sympathetic nerves. Adrenalectomy of the rats did not affect the cooling‐induced response.

The P2 purinoceptor antagonists suramin and PPADS also significantly suppressed the cooling‐induced reduction of PSBF. However, the inhibitory effect of PPADS on the cooling‐induced response was abolished after the treatment with phentolamine. Intra‐arterial injections of ATPγS, a stable P2 purinoceptor agonist, at 25°C caused a transient decrease in PSBF in a dose‐dependent manner, which was significantly inhibited by phentolamine and guanethidine.

These results suggest a novel mechanism for local cooling‐induced reduction of skin blood flowin vivo; moderate cooling of the skin induces the release of ATP, which stimulates presynaptic P2 purinoceptors on sympathetic nerve terminals and facilitates the release of noradrenaline, thereby causing contractions of skin blood vesselsviathe activation ofα1‐andα2‐adrenoceptors.

British Journal of Pharmacology(2006)148, 579–586. doi:10.1038/sj.bjp.0706765