bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐term nigral transplants in rat striatum: An electron microscopic study
Authors: Gopinath Gomathy , Sailaja K. , Tandon P.N.
Published: January 2005

The substantia nigra of gestation day 14 was transplanted into the striatum of 3–4‐month‐old rats to investigate the transplants ultrastructurally at the end of 2 years, as a follow‐up to our previous studies. Transplants were of small size in all 10 specimens taken for this study. The changes observed in the transplant and in the interface region with the host striatum were: thickening of the blood vessel walls, perivascular cuffing with lymphocytes and macrophages loaded with tissue debris, degenerating neurons and hypertrophied astroglia containing dense granules indicating ageing or reaction to degeneration and glial processes. The number of surviving neurons in the transplants was small. These were smaller in size and had very few intracytoplasmic membraneous organelles. A higher content of intracytoplasmic ageing lipofuscin pigment was present than in host neurons and age‐matched nigral neurons. Synapses were few, and their number varied among transplants. Generally, the synapses were at the interface with the host tissue. The changes observed in all the 2‐year‐old transplants suggest premature ageing or a slow rejection process. Slow rejection is a possibility, because these rats are only stock‐bred, not inbred, and hence they are not completely immunologically compatible.
Neuron‐glia interrelations during migration of Purkinje cells in the mouse embryonic cerebellum
Authors: Yuasa Shigeki , Kawamura Koki , Kuwano Ryozo , Ono Katsuhiko
Published: January 2005

The interrelations between migratory Purkinje cells and radial glial processes were examined immunohistochemically and electron‐microscopically in the fetal mouse cerebellum. Migratory Purkinje cells identified immunochemically with anti‐spot 35 antibody were apposed to the presumed radial glial processes. Putative immature migratory Purkinje cells were apposed to the radial glial processes identified immunochemically with monoclonal antibody 1DI I or anti‐tenascin antibody. Junctional specializations related to cell adhesion were observed at the sites of contact between the immature neurons and glial processes. Furthermore, coated vesicles and coated pits were noted in the contact region. These findings support the concept of contact guidance of migratory Purkinje cells by radial glial processes through cell adhesion, and also suggest the trophic interactions occurring at the region of contact.
Effects of ischemia‐hypoxia induced by interruption of uterine blood flow on fetal rat liver and brain enzyme activities and offspring behavior
Authors: Binienda Z. , Holson R.R. , Chen F.‐X. , Oriaku E. , Kim C.S. , Flynn T.J. , Slikker W. , Paule M.G. , Feuers R.J. , Ferguson S.A.
Published: January 2005

The effects of acute perinatal ischemia‐hypoxia on fetal liver and brain energy metabolism, fetal brain total free fatty acid concentration and subsequent offspring behavior were investigated in rats. Ischemia‐hypoxia was induced at term either by ligation of the uterine blood vessels or submersion of the entire uterine horn in warmed saline. Fetuses of the adjacent horn served as within‐dam controls for all assessments and fetuses of dams which had not undergone the surgical stress served as independent controls for enzyme assays. Ischemia‐hypoxia was associated with reduced activity of fatty acid synthase in the liver and brain. Total free fatty acid concentration significantly increased in the fetal hypoxic brain. Pups not used for enzyme analyses were cross‐fostered for behavioral assessments. Relative to the enzymatic alterations, there were few behavioral alterations associated with ischemia‐hypoxia. At postnatal day 30, rats made hypoxic by ligation of the uterine blood vessels had decreased caudate nucleus and brain stem weights relative to within‐dam controls. At postnatal day 85, rats made hypoxic by submersion of the uterine horn had decreased olfactory bulb weight. The results of this study indicate an initial acute response to a brief period of ischemia‐hypoxia at term pregnancy in the fetal rat brain and liver.
Effect of growth factors on the in vitro growth and differentiation of early and late passage C6 glioma cells
Authors: Goya Luis , Feng Pei‐Ti , Aliabadi Samira , Timiras Paola S.
Published: January 2005

The effect of different hormones and growth factors was assayed on the in vitro growth and enzymatic activities of 2′,3′‐cyclic nucleotide 3′phosphohydrolase (CNP) and glutamine synthetase (GS) of rat glioma C6 cells at two different passages in culture. Young cultures (passage 26), mainly oligodendrocytic, and older cultures (passage 134), predominantly astrocytic, were treated with 10 μM dexamethasone, 20 ng/ml transforming growth factor alpha (TGFα), 10 ng/ml insulin, 20 ng/ml platelet‐derived growth factor (PDGF), and 20 ng/ml, epidermal growth factor (EGF) in serum‐free chemically defined media. In vitro growth rate was measured in terms of DNA content, by a fluorometric method of diaminobenzoic acid, and rate of DNA synthesis by 3H‐thymidine incorporation. CNP activity (marker for in vitro oligodendrocytes) and GS activity (marker for astrocytes) were determined spectrophotometrically. Dexamethasone reversibly and significantly inhibited growth of C6 glioma in early and late passages. PDGF and insulin promoted in vitro growth only in late passage but not in early passage cells, whereas EGF and TGFα did not significantly affect growth. An increase in CNP activity was observed in early passage cells under the effect of PDGF and insulin. The increase in GS activity induced by insulin and dexamethasone suggests a differentiating role for these factors in C6 glioma cells. These results further present the C6 glioma cell line as a useful model for studies on glial cell properties and responsiveness in culture and support its use in experimental aging in vitro.
Colour M‐mode velocity propagation: a glance at intra‐ventricular pressure gradients and early diastolic ventricular performance
Authors: De Boeck Bart W.L. , Oh Jae K. , Vandervoort Pieter M. , Vierendeels Jan A. , van der Aa Ronald P.L.M. , Cramer Maarten‐Jan M.
Published: January 2005

The physiology of early‐diastolic filling comprises ventricular performance and fluid dynamical principles. Elastic recoil and myocardial relaxation rate determine left ventricular early diastolic performance. The integrity of left ventricular synchrony and geometry is essential to maintain the effect of their timely action on early diastolic left ventricular filling. These factors not only are prime determinants of left ventricular pressure decay during isovolumic relaxation and immediately after mitral valve opening; they also instigate the generation of a sufficient intra‐ventricular pressure gradient, which enhances efficient early diastolic left ventricular filling. Accurate assessment of diastolic (dys)function by non‐invasive techniques has important therapeutic and prognostic implications but remains a challenge to the cardiologist. The evaluation of left ventricular relaxation by the standard Doppler echocardiographic parameters is hindered by their preload dependency. The colour M‐mode velocity propagation of early diastolic inflow (Vp) correlates with intra‐ventricular pressure gradients and is a largely preload independent index of ventricular diastolic performance. In this article, the physiologic background, utility and limitations of this promising new tool for the study of early diastolic filling are reviewed.
Activation of UCPs gene expression in skeletal muscle can be independent on both circulating fatty acids and food intake
Authors: Busquets Sílvia , Almendro Vanessa , Barreiro Esther , Figueras Maite , Argilés Josep M. , López-Soriano Francisco J.
Published: January 2005

Implantation of a fast growing tumour to mice (Lewis lung carcinoma) resulted in a clear cachectic state characterized by a profound muscle wasting. This was accompanied by a significant increase in both UCP2 and UCP3 gene expression in skeletal muscle and heart. Interestingly, this increase in gene expression was not linked to a rise in circulating fatty acids or in a decrease in food intake, as previously reported in other pathophysiological states. These results question the concept that hyperlipaemia is the only factor controlling UCP gene expression in different pathophysiological conditions. In addition, the present work suggests that UCPs might participate in a counter‐regulatory mechanism to lower the production of ROS.
Oesophageal strictures in cats associated with doxycycline therapy
Authors: German Alexander James , Cannon Martha Jane , Dye Charlotte , Booth Malcolm John , Pearson Geoffrey Robert , Reay Caroline Anne , Gruffydd-Jones Timothy John
Published: January 2005

Four cases of oesophageal stricture subsequent to doxycycline administration are reported. All cases were young to middle age (median age 3 years; range 1–7 years), and either domestic shorthair or domestic longhair breed. In all cases the predominant clinical sign was regurgitation, which developed at variable times after doxycycline administration. In all cases the reason for doxycycline use was treatment or prophylaxis of suspected infections ( Mycoplasma haemofelis, Chlamydophila felis or Bordetella bronchiseptica), and the duration of therapy was variable. In one case the stricture was definitively diagnosed at post mortem examination, in the three other cases, definitive diagnosis was by endoscopy. Balloon dilation was successful in the three cases that were treated. This is the largest case series, to date, of oesophageal disease in cats associated with doxycycline administration. Caution should be exercised when administering oral medication to cats, especially doxycycline, and should be accompanied either by a water or food swallow.
State Collaboration and Development Strategies in China: The Case of the China–Singapore Suzhou Industrial Park (1992–2002). By Alexius A. Pereira. [London and New York: RoutledgeCurzon,
2003. 189 pp. ISBN 0-415-30277-3.]
Authors: Thun Eric
Published: January 2005

Take a drive through the Suzhou Industrial Park (SIP) and you will see what appears to be a model industrial estate: cleanly laid out roads interspersed with green parks and endless rows of factories humming with activity. There is none of the chaotic, thrown-together feel of so many Chinese industrial parks; the atmosphere is almost serene. Talk to the managers of these factories and you will hear nothing but praise for the managers of the park. Even the biggest problems – the rapidly rising cost of land, the shortage of workers – are indications of success. Surprisingly, and despite these outward appearances, the SIP was, until recently, viewed by many as a grave disappointment.

The SIP was not supposed to be just another industrial park in China: it was a grand experiment. The idea was to transplant the strengths of the Singaporean model – effective bureaucratic management, world-class infrastructure and a stable business environment – to China through government co-operation. The park was a joint venture between a foreign consortium directed by the Singaporean government and a Chinese consortium consisting of local governments and centrally-controlled, state-owned enterprises. From the perspective of the Chinese government, the hope was that the SIP would provide a model of effective governance for the rest of the country at the same time as it served as an engine of growth in the Jiangsu region. From the perspective of the Singaporean government, the SIP was partly an attempt to capitalize upon its strength in management in a location with far lower costs, and partly an attempt to demonstrate the relevance of the Singaporean “model” in a Chinese context. The stakes were high for both parties.
Changing China: A Geographic Appraisal. Edited by Chiao-Min Hsieh and Max Lu. [Oxford and Boulder, CO: Westview Press, 2003. 512 pp. $48.00. ISBN 0-8133-3474-8.]
Authors: Gaubatz Piper
Published: January 2005

One of the greatest challenges to those researching and lecturing on China today is the country's rapid rate of change. To date, there have been only a handful of timely general texts for use in English-language geography and other social science courses. These have included single authored efforts, such as Christopher Smith's China: People and Places in the Land of One Billion (1991), Frank Leeming's The Changing Geography of China (1993) and Songqiao Zhao's Geography of China: Environment, Resources, Population and Development (1994); and edited collections such as Terry Cannon and Alan Jenkins' The Geography of Contemporary China: The Impact of Deng Xiaoping's Decade (1990), Gregory Veeck's The Uneven Landscape: Geographic Studies in Post-Reform China (1991), and Robert Gamer's Understanding Contemporary China (2003). Although each of these books remains an important and valuable contribution to the literature and to the teaching of courses on China, the remarkable pace of change in China has rendered them out of date in less than a decade.

In this context, it is good to see a new contribution. Using China's rapid post-1978 change as a theme, geographers Chiao-min Hsieh and Max Lu have assembled Changing China: A Geographic Appraisal, an edited collection of 26 chapters, in 500 pages. These chapters, largely written by geographers, are organized into three sections entitled “Economic changes,” “Social changes” and “Changes along China's periphery.” The primary strength of the book is its breadth. Although it addresses neither physical geography nor China's environmental issues, it does speak to a wide range of human geographic questions, from land use and agricultural development to population and economy. The majority of the chapters, with a few exceptions, are well grounded within the authors' own research foci and expertise. The most notable weakness of the book is one shared by many edited collections: that it lacks integration and a sense of dialogue between the chapters. This weakness might have been overcome through a face to face meeting of the authors, through an exchange of chapter drafts, through editorial guidance, or through more extensive section introductions and summaries by the editors. This type of integration is, of course, rare.
Incorporating ecological perspectives in European groundwater management policy
Authors: DANIELOPOL DAN L. , GIBERT JANINE , GRIEBLER CHRISTIAN , GUNATILAKA AMARA , HAHN HANS JÜRGEN , MESSANA GIUSEPPE , NOTENBOOM JOS , SKET BORIS
Published: January 2005

Implementation of the European Union (EU) Water Framework Directive (WFD 2000) and its planned supplement ‘Directive on the Protection of Groundwater against Pollution’ (EU GWD [European Union Groundwater Directive] 2003) demands an initial characterization of all groundwater bodies by national and regional authorities. The main criteria considered in the Directives to define the groundwater (GW) status are quality (chemical) and quantity, but there is the obvious omission of ecological perspective in these. A directive for a comprehensive policy dealing with GW protection at the level of the EU is a prerequisite for human welfare. Additionally, recognition of GW-dependent ecosystems (GDEs) in the EU is equally important for their sustainable management. GW management and policy should recognize the ecological functions of GW and their interactions with GDEs. As they can stretch across national and regional boundaries, political recognition of their importance and the necessity for ecological consistency of management plans have to be emphasized. During the last three decades, a number of researchers have focused their attention on the dynamics and functioning of GW ecosystems and this work could serve as a basis for identifying impacts of changes in key attributes of GDEs. Detailed aspects of GW ecosystems have been comprehensively dealt with (Gibert et al. 1994; Wilkens et al. 2000; Griebler et al. 2001; Danielopol et al. 2003). Changes in key attributes of GW ecosystems have had consequences for the environment in the EU and USA (Klijn & Witte 1999; Winter 1999; Sophocleous 2002; Winter et al. 2003).
Unforeseen effects of ecosystem restoration on yellow-legged gulls in a small western Mediterranean island
Authors: MARTÍNEZ-ABRAÍN A. , SARZO B. , VILLUENDAS E. , BARTOLOMÉ M. A. , MÍNGUEZ E. , ORO D.
Published: January 2005

A conservation project aimed at ecosystem restoration had several unforeseen effects on a colony of the yellow-legged gull Larus michahellis in a small western Mediterranean island (Benidorm Island). The project included regulation of massive tourist visits to help restore the soil and autochthonous vegetation. However, gulls habituated rapidly to regulation of tourist activities, as nests located either close to or far from the main trail showed a similar hatching success. The quiet conditions produced by regulation seemingly facilitated a rapid colony increase. Partial removal of alien vegetation (Opuntia maxima) showed that gulls had a preference for sites with high vegetation cover because the growth of the colony was proportionally larger in well-vegetated plots. The pricking of a large number of gull eggs surprisingly coincided with a high reproductive success compared to the previous year, although indicators of food availability remained constant between years and the colony had decreased in numbers. Untreated nests were probably more successful because territory size for chicks increased and intraspecific predation decreased. Extreme care must be taken when planning ecosystem-wide management on islands with yellow-legged gull colonies, or other gull species locally considered as pests, to prevent unwanted effects.
Traditional knowledge and satellite tracking as complementary approaches to ecological understanding
Authors: HUNTINGTON HENRY P. , SUYDAM ROBERT S. , ROSENBERG DANIEL H.
Published: January 2005

The integration or co-application of traditional knowledge and scientific knowledge has been the subject of considerable research and discussion (see Johannes 1981; Johnson 1992; Stevenson 1996; McDonald et al. 1997; Huntington et al. 1999, 2002), with emphasis on various specific topics including environmental management and conservation (see Freeman & Carbyn 1988; Ferguson & Messier 1997; Ford & Martinez 2000; Usher 2000; Albert 2001). In most cases, examples of successful integration compare traditional and scientific observations at similar spatial scales to increase confidence in understanding or to fill gaps that appear from either perspective. We present a different approach to integration, emphasizing complementarity rather than concordance in spatial perspective, using two migratory species as examples.
Can methods applied in medicine be used to summarize and disseminate conservation research?
Authors: FAZEY IOAN , SALISBURY JANET G. , LINDENMAYER DAVID B. , MAINDONALD JOHN , DOUGLAS ROBERT
Published: January 2005

To ensure that the best scientific evidence is available to guide conservation action, effective mechanisms for communicating the results of research are necessary. In medicine, an evidence-based approach assists doctors in applying scientific evidence when treating patients. The approach has required the development of new methods for systematically reviewing research, and has led to the establishment of independent organizations to disseminate the conclusions of reviews. (1) Such methods could help bridge gaps between researchers and practitioners of environmental conservation. In medicine, systematic reviews place strong emphasis on reviewing experimental clinical trials that meet strict standards. Although experimental studies are much less common in conservation, many of the components of systematic reviews that reduce the biases when identifying, selecting and appraising relevant studies could still be applied effectively. Other methods already applied in medicine for the review of non-experimental studies will therefore be required in conservation. (2) Using systematic reviews and an evidence-based approach will only be one tool of many to reduce uncertainty when making conservation-related decisions. Nevertheless an evidence-based approach does complement other approaches (for example adaptive management), and could facilitate the use of the best available research in environmental management. (3) In medicine, the Cochrane Collaboration was established as an independent organization to guide the production and dissemination of systematic reviews. It has provided many benefits that could apply to conservation, including a forum for producing and disseminating reviews with emphasis on the requirements of practitioners, and a forum for feedback between researchers and practitioners and improved access to the primary research. Without the Cochrane Collaboration, many of the improvements in research communication that have occurred in medicine over the last decade would not have been possible.
Damage reduction estimates and benefit-cost ratios for feral swine control from the last remnant of a basin marsh system in Florida
Authors: ENGEMAN RICHARD M. , SMITH HENRY T. , SEVERSON ROBERT , SEVERSON MARY ANN , WOOLARD JOHN , SHWIFF STEPHANIE A. , CONSTANTIN BERNICE , GRIFFIN DANIEL
Published: January 2005

The introduction of swine (Sus scrofa) has adversely affected the environment of many natural habitats throughout the world. Basin marshes are dwindling ecosystems in Florida that are especially vulnerable to damage by feral swine. In January 2003, the estimated amount of swine damage to the exposed portion of the last remnant of a basin marsh system in Savannas Preserve State Park (SPSP) was 19% (an area of 5 ha). Economic valuations for the swine damage were based on the monetary amounts that wetland regulators have allowed permit applicants to spend in mitigation attempts to replace lost wetland resources. In 2003, the area of natural habitat damaged by swine had a total value of US$ 1 238 760–4 036 290. The SPSP implemented a contract for swine control throughout 2003 in all areas of the Park. The damage to the basin marsh was re-estimated in January 2004, after swine removal. The damage sampling transects remained the same as the 2003 survey, but damage was significantly reduced, with 31% of sampling transects showing damage in January 2004 versus 92% in January 2003. Similarly, the total area of swine damage had decreased to 0.95 ha, and the value of the lost habitat had been reduced to US$ 235 355–766 865, an economic benefit of US$ 1 003 355–3 269 265. The benefit-cost ratio (BCR) relating the economic value of the damage reduction against the swine control costs (not all swine control in the park was carried out in the vicinity of the basin marsh) was conservatively estimated at 134–436. When estimating costs for swine control in the vicinity of the marsh based on the proportional number of swine removed there as compared to the Park as a whole, the BCR increased to 480–1562. Benefits of swine removal are very high relative to the costs of control.
Bias in evaluating the effects of marine protected areas: the importance of baseline data for the Galapagos Marine Reserve
Authors: EDGAR G.J. , BUSTAMANTE R.H. , FARIÑA J.-M. , CALVOPIÑA M. , MARTÍNEZ C. , TORAL-GRANDA M.V.
Published: January 2005

Analysis of ecological baseline data collected for key resource species within the Galapagos Marine Reserve indicates that variation in animal density associated with the location of fully protected zones can be comparable to protected area effects. Even with a high level of interspersion between conservation, tourism and fishing management zones, major differences in densities of economically important species were evident between zone types prior to enforcement of fishing restrictions. Densities of the most valuable fishery resource, sea cucumbers, were three times higher in zones that remained open to fishing compared to ‘no-take’ conservation zones, and densities of sharks were five times higher in tourism zones than fishing or conservation zones. These results highlight bias in the socio-political processes that can accompany selection of marine protected areas, where fishers attempt to minimize perceived impacts on their livelihood by locating large protected zones in resource-poor areas, and tourism operators and sport divers argue for protection of areas containing atypically-interesting features. Bias in the location of fully protected zones can seriously confound ‘control-impact’ field investigations when data prior to prohibitions on fishing are lacking, including meta-analyses, which are dominated by such potentially systematically biased studies.
Toward noncontacting seismology
Authors: van Wijk K. , Scales J. A. , Mikesell T. D. , Peacock J. R.
Published: January 2005

Buried land mines and chemical waste may provide the contrast in elastic properties within the soil needed to achieve detection via near‐surface seismic methods. The hazardous nature of these targets strongly indicates the use of noncontacting sources and receivers. A home‐made ultrasonic parametric array allows us to insonify the soil with an intense beam of sound; this acoustic energy is converted to elastic waves in the soil. Our noncontacting seismometer is a microwave Doppler vibrometer that can detect seismic waves, even through grass. We believe that developments along these lines will ultimately lead to the ability to probe large areas of the near‐surface in a safe and reliable fashion, without physically touching the ground.
Diagnosis of the tropical Atlantic near‐equatorial SST bias in a directly coupled atmosphere‐ocean general circulation model
Authors: DeWitt David G.
Published: January 2005

The current generation of non‐flux‐corrected coupled atmosphere‐ocean general circulation models (CGCMs) have trouble correctly simulating the sign of the annual mean near‐equatorial east to west gradient of sea surface temperature (SST) in the Atlantic Ocean. This model pathology is of concern because the distribution of tropical oceanic precipitation is related to the near‐equatorial SST distribution. The tropical oceanic precipitation, in turn, influences local and remote precipitation over the tropical land areas through various teleconnection mechanisms. Therefore, understanding and eventually fixing this model error is of interest. In this study, the cause of the Atlantic equatorial SST gradient error in one CGCM is investigated using forced experiments with the CGCM ocean component model. These experiments show that the most likely candidate for this error is the too‐weak zonal wind stress along the equator in the coupled model. This wind stress error affects the SST along the equator in two ways. First, it leads to a deepening of the thermocline in the eastern part of the basin and a shallowing in the western part. Second, the weak zonal stress leads to a vertical velocity distribution at the based of the mixed layer that is too weak in the eastern and central Atlantic and too strong in the western Atlantic. Both of these errors lead to insufficient cooling of the eastern near equatorial mixed layer and erroneously enhanced cooling in the western near equatorial mixed layer.
Validation of Moderate Resolution Imaging Spectroradiometer leaf area index product in croplands of Alpilles, France
Authors: Tan Bin , Hu Jiannan , Zhang Ping , Huang Dong , Shabanov Nikolay , Weiss Marie , Knyazikhin Yuri , Myneni Ranga B.
Published: January 2005

This paper presents results of validating the Collection 4 Moderate Resolution Imaging Spectroradiometer (MODIS) leaf area index (LAI) product using LAI data collected in a 3 × 3 km agricultural (grasses and cereal crops) area near Avignon, France, and 30 m resolution Enhanced Thematic Mapper (ETM+) image. Estimates of the accuracy, precision, and uncertainty with which the ETM+ data convey information about LAI underlie the derivation of a 30 m resolution reference LAI map by accounting for both field measurement and satellite observation errors. The 30 m reference LAI was then extrapolated from sampling points to a 58 km2 area without loss in the quality and was degraded to a 1 km resolution LAI map. The latter was taken as a reference to assess the quality of the MODIS LAI product. Comparison of the reference and corresponding MODIS retrievals suggests that Collection 4 MODIS LAI is accurate to within an accuracy of 0.3 with a precision and uncertainty of 0.23 and 0.38, respectively. It was found that the Collection 3 MODIS land cover product, input to the Collection 4 operational LAI algorithm, misclassified the 58 km2 area as broadleaf crops. The use of correct biome type in the operational processing improves the accuracy in LAI by a factor of 2 with an almost unchanged precision and uncertainty. Our results also indicate that the retrieval of LAI from satellite data is an ill‐posed problem; that is, small variations in input due to observation errors result in a very low precision of the desired parameter. Any retrieval technique based on a simple model inversion or empirical relationships is unable to generate stable retrievals. The use of information on input errors in the retrieval technique is necessary to generate solutions to the ill‐posed problem. The MODIS operational LAI algorithm meets this requirement.
Determination of GPS receiver differential biases by neural network parameter estimation method
Authors: Ma X. F. , Maruyama T. , Ma G. , Takeda T.
Published: January 2005

The dual‐frequency signals of GPS can be used to measure the total electron content (TEC). The differential instrumental biases inherent in GPS satellite and receivers are considered as the main sources of error, and they must be removed for an accurate estimation of TEC. We aim at developing an effective method to solve the difficulties involved in the TEC measurement; there are only a few usable ground receivers, especially in lower‐latitude areas near the geomagnetic equator where large ionospheric variability exists. For this purpose a new parameter estimation method based on a residual minimization training neural network is applied to determination of the GPS receiver biases. The alternative method is realized by making use of the excellent features of neural networks to approximate a wide range of mapping functions, for which the network training is carried out by minimizing squared residuals of integral equation. To determine receiver biases (unknown parameters), we used additional “neural networks,” each of which consists of only one neuron without an input channel. It is assumed that satellite biases have already been determined by applying the least squares method to the GEONET data gathered by a large number of receivers. Various cases of observation data for different seasons, different local times, and different geographic locations of the receiver as well as the cases of model data are analyzed, and it is confirmed that the method is very effective for a small number of receivers located in the lower‐latitude areas.
Intravenous anaesthetics inhibit nicotinic acetylcholine receptor‐mediated currents and Ca2+ transients in rat intracardiac ganglion neurons
Authors: Weber Martin , Motin Leonid , Gaul Simon , Beker Friederike , Fink Rainer H A , Adams David J
Published: January 2005

The effects of intravenous (i.v.) anaesthetics on nicotinic acetylcholine receptor (nAChR)‐induced transients in intracellular free Ca2+ concentration ([Ca2+]i) and membrane currents were investigated in neonatal rat intracardiac neurons.

In fura‐2‐loaded neurons, nAChR activation evoked a transient increase in [Ca2+]I, which was inhibited reversibly and selectively by clinically relevant concentrations of thiopental. The half‐maximal concentration for thiopental inhibition of nAChR‐induced [Ca2+]i transients was 28 μM, close to the estimated clinical EC50 (clinically relevant (half‐maximal) effective concentration) of thiopental.

In fura‐2‐loaded neurons, voltage clamped at −60 mV to eliminate any contribution of voltage‐gated Ca2+ channels, thiopental (25 μM) simultaneously inhibited nAChR‐induced increases in [Ca2+]i and peak current amplitudes. Thiopental inhibited nAChR‐induced peak current amplitudes in dialysed whole‐cell recordings by ∼ 40% at −120, −80 and −40 mV holding potential, indicating that the inhibition is voltage independent.

The barbiturate, pentobarbital and the dissociative anaesthetic, ketamine, used at clinical EC50 were also shown to inhibit nAChR‐induced increases in [Ca2+]i by ∼40%.

Thiopental (25 μM) did not inhibit caffeine‐, muscarine‐ or ATP‐evoked increases in [Ca2+]i, indicating that inhibition of Ca2+ release from internal stores via either ryanodine receptor or inositol‐1,4,5‐trisphosphate receptor channels is unlikely.

Depolarization‐activated Ca2+ channel currents were unaffected in the presence of thiopental (25 μM), pentobarbital (50 μM) and ketamine (10 μM).

In conclusion, i.v. anaesthetics inhibit nAChR‐induced currents and [Ca2+]i transients in intracardiac neurons by binding to nAChRs and thereby may contribute to changes in heart rate and cardiac output under clinical conditions.

British Journal of Pharmacology (2005) 144, 98–107. doi:10.1038/sj.bjp.0705942
Fine Grain Photographic Development
Authors: Higgins George
Published: January 2005

The effect of different fine grain photographic developers upon the effective emulsion speed and graininess of photographic materials was studied quantitatively. Fine grain developers were found to be more effective in reducing the graininess of fast, coarse grain emulsions than of slow, fine grain emulsions. The effective emulsion speed of slow, fine grain emulsions when developed in an MQ borax developer was found to be at least equal to that of a fast, coarse grain emulsion when developed in an ultra-fine grain developer which gave negatives of as low graininess on the fast emulsion as the MQ borax gave on the slow emulsion. Slight improvement in graininess can be obtained by using ultra-fine grain developers on fine grain emulsions, but only at some sacrifice of effective emulsion speed.
A Resonance Curve Method for the Absolute Measurement of Impedance at Frequencies of the Order 300 mc/Second
Authors: Chipman R. A.
Published: January 2005

A general theory is developed, together with a simplified experimental procedure, which permits the absolute measurement of the magnitude and phase angle of any value of complex impedance, in terms of the characteristic impedance of a parallel-wire line to which the impedance to be measured is connected as one termination. The observed quantities are the shape of the resonance curve of the current in one of the line's terminations obtained by varying the line length, and the length of line for maximum current. The effects of distributed line resistance and of radiation resistance on the impedance measurements are discussed in detail. Examples are given of the measurement of the impedance of straight resistance wires, and of the resistance of ``metallized'' resistors, at a frequency of 377 mc/sec.

The accuracy of the method varies considerably throughout the total range of resistance and reactance, but is high for any combination of the two from a few ohms to a few thousand ohms. The possible accuracy varies approximately inversely as the frequency. At a frequency of 300 mc/sec. an optimum accuracy of about one percent may be expected.

In an appendix some experimental data on the radiation resistance of a parallel-wire line are described.
Studies in Lubrication. III. The Theory of the Thick Film Lubrication of a Complete Journal Bearing of Finite Length with Arbitrary Positions of the Lubricant Source
Authors: Muskat M. , Morgan F.
Published: January 2005

A successive approximation theory is developed for the thick film lubrication of complete journal bearings of finite length for arbitrary positions of the lubricant source. It has been carried through in detail up to the third approximation, which permits studies of systems having journal eccentricities up to the value of ½. The range of bearing length for which the theory is valid includes such as are of the order of, or greater than, half the bearing perimeter. Detailed calculations are reported on the inter-relationships between the attitude of the line of centers of the journal and bearing, the journal eccentricity, the lubricant source strength, the ``Sommerfeld variable,'' (r2/c2)μN/P—where r=journal radius, c=radial clearance, μ=lubricant viscosity, N=journal speed and P=bearing load per unit projected bearing area—and the coefficient of friction, both for lubricant sources set at the crown and base of the bearing. Most of the numerical results refer to the case where the bearing length equals the bearing perimeter. In general it is found that when the lubricant source is at the crown or unloaded portion of the bearing, it tends to increase the journal eccentricities, oppose the journal supporting forces caused by the journal rotation, and increase the friction coefficients. When the source is set at the base, or loaded side, of the bearing, and has a strength less than the ``critical value,'' determined by the bearing length, it tends to decrease the journal eccentricities, to aid in supporting the load, and to decrease the friction coefficients on the journal. At the ``critical values'' of source strength the journal becomes concentric with the bearing and the lubricant source alone supports the load. For higher values of source strength the journal is raised above the center of the bearing so that the journal rotation detracts from the load-carrying power of the film, and the friction coefficient on the journal begins to rise. Moreover, when the source is set at the base of the bearing, the friction coefficient curves for both the bearing and journal, when plotted against the Sommerfeld variable, all go through the origin in contrast to the infinitely long bearing theory where the coefficient of friction on the journal has a unit friction axis intercept. From the hydrodynamic point of view there are therefore no minima in the curves, or suggestions of thin film friction rises when the lubricant source is at the base of the bearing.
The Viscosity of Dilute Solutions of Long-Chain Molecules. III. The Staudinger Viscosity Law
Authors: Huggins Maurice L.
Published: January 2005

An equation has recently been derived for the specific viscosity of a dilute solution of ``randomly-kinked'' chain molecules, which, for long chains and small concentrations, is of the same form as Staudinger's empirical ``law'': ηsp = ksnc. The validity of this equation for actual solutions, and the nature and magnitude of the deviations to be expected are discussed. Among the effects considered are those due to restriction of rotation about the bonds in the chain and to the size and nature of the solvent molecules, of the repeating units in the chain, and of the end groups.
The Motion of Cylindrical Particles in Viscous Flow
Authors: Binder R. C.
Published: January 2005

Experiments were made on the orientation of cylindrical particles in viscous flow. Particles were immersed in a moving fluid between two concentric cylinders. Tests showed two different final orientations: (1) a position perpendicular to the plane of the undisturbed flow, and (2) a position parallel to the velocity direction. The relation between the final orientation and the length-diameter ratio of the particle was found for different speeds. Comparison is made between the experimental results and theoretical predictions.
Limiting Current Densities in Electron Beams
Authors: Pierce J. R.
Published: January 2005

In electron beam devices the thermal velocities of the electrons leaving the cathode limit the current density which can be attained with given cathode current density, cathode temperature, potential, and angular spread of arriving electrons. By using Liouville's theorem, limiting expressions are obtained which are valid for any point focus or line focus concentrating system using steady electric and magnetic fields. Current densities in perfectly focused beams are also evaluated. Curves are presented which relate the nearness of approach to the maximum attainable current density with the fraction of cathode current necessarily lost in the concentrating system. Use of the expressions obtained is illustrated by applying them to cathode ray tubes and electron multipliers.
Current Densities, Lumen Efficiency and Brightness in A, N2, He and H2 Arcs
Authors: Suits C. G.
Published: January 2005

From oscillographic records of arc diameter D, gradient E, current i, and comparative brightness data, the lumen efficiency and current densities are determined for the positive column of arcs in A, N2, He and H2 in the pressure range between 1 and 100 atmospheres.
Infra-Red Spectra—Observation and Uses
Authors: Randall H. M.
Published: January 2005

A nontechnical description is presented of methods of observation now in general use in infra-red spectroscopy, together with some typical examples of their use.
Increase of Torsional Stiffness of a Prismatical Bar Due to Axial Tension
Authors: Biot M. A.
Published: January 2005

The author's theory of elasticity of the second order is being applied to calculate the increase of torsional stiffness of a prismatical bar when an axial tension is initially imposed upon it. It is found that the classical shear stress distribution is not affected by the axial stress. However, an increase of torsional stiffness is produced due to the fact that the boundary condition over the cross section contains not only the shearing stress but also the product of the axial stress by the rotations. This increase of torsional stiffness turns out to be proportional to the polar moment of inertia of the cross section with respect to its center of gravity.
The Theory of Klystron Oscillations
Authors: Webster David L.
Published: January 2005

The principles governing the oscillations in a klystron may be divided into four groups: (1) those of space resonance within each rhumbatron, previously discussed by Hansen; (2) the equations of coupled circuits, with modifications appropriate to space-resonant systems; (3) the kinematics and dynamics of cathode-ray bunching, previously discussed by the author; (4) the constraint on phase relations between the rhumbatrons introduced by the cathode-ray bunches. It is shown here that (4) makes the oscillations assume forms very different from those familiar in free oscillations. These forms are described by general equations and then these equations are applied to three specific problems: maximizing the power output from an oscillator, minimizing the power input for an ideal regenerative amplifier, and finding how stable the frequency is against changes in cathode potential.
The Atomphysical Interpretation of Lichtenberg Figures and Their Application to the Study of Gas Discharge Phenomena
Authors: Merrill F. H. , Von Hippel A.
Published: January 2005

The extremely finely detailed drawing in Lichtenberg figures offers an unusually clear record of the early stages of discharge phenomena. The interpretation of these records in terms of electronic ionization, space charge, plasma formation, and neutralization of charges is presented in this paper. After giving a short summary of our present knowledge about gas breakdown, the ``normal'' history of a Lichtenberg discharge is established by a study in nitrogen between five millimeters of mercury and thirty atmospheres of pressure. It progresses in three stages—the primary figure, spark development, and the discharge of negative surface charges. (The ``back figure.'') Admixture of carbon tetrachloride and experiments in ``Freon'' up to six atmospheres show the decisive influence of electro-negative components on the development of the phenomena, and reveal the reasons why these new gases are so effective in suppressing corona discharges. Deviations from Paschen's law, recently observed by several workers, can be interpreted in terms of the photographic evidence gained.
Nerve Conduction with Distributed Capacitance
Authors: Weinberg Alvin M.
Published: January 2005

Rashevsky's theory of nerve conduction has been extended to include the effects of distributed capacitance along the fiber. The simple theory of Rashevsky, based on the idea of local re-excitation by bioelectric currents according to Blair's law of excitation, leads to a formula for the initial velocity of the nerve impulse: v=aklogA0/(A0−R),where a is the distance between Ranvier nodes, k is related to the chronaxie of the nerve, A0, is the local exciting current, and ℛ is the threshold for excitation. This result does not depend explicitly on G, the node leakance. The present analysis gives for the initial velocity, in case G/C»k, v=aklogA0/(A0−(R+A0ψ)),where ψ is a complicated function of C and vanishes when C=0. In case G/C is not »k, the velocity is given as the root of a transcendental equation which may be solved graphically. Formulae for the asymptotic velocity of propagation are similarly related in Rashevsky's and the present case. Empirical data necessary to check the validity of these results are as yet unavailable; the type of experiments needed to obtain these data are suggested.
Problem of Ice Formation
Authors: Pekeris C. L. , Slichter L. B.
Published: January 2005

A solution of the nonlinear problem of the rate of ice formation on a long cylinder whose surface temperature is variable (but always below 0°C) is given. The first-order correction to the steady-state solution is evaluated and found to be small. As an example, application is made to a specific problem in freezing soil.
On Resonators Suitable for Klystron Oscillators
Authors: Hansen W. W. , Richtmyer R. D.
Published: January 2005

Various resonators, of the hohlraum type, suitable for driving by the klystron method, are described and their leading properties computed. Various mathematical techniques are used, including the application, for the first time in this field, of Stevenson's method of determining a lower bound for the frequency.
A Note on the Quantitative Spectrographic Analysis of Small Amounts of Rubidium and Potassium in Biological Materials
Authors: Cohn Willi M.
Published: January 2005

The sample is placed into the capillary of a gas discharge tube operated under standardized conditions. The emission spectrum is investigated from 3500 to 8500A. Intensity marks are printed on each plate. The blackening of the Rb and K lines is measured. Equivalent amounts of RbCl and KCl in the sample are obtained graphically from curves derived from standard samples. The method seems of special interest in cases where small samples only are available.
Measurement of Some Arc Characteristics at 1000 Atmospheres Pressure
Authors: Suits C. G.
Published: January 2005

By an oscillographic method the total arc voltage e is measured as a function of arc current i at high pressure in a 1500-volt d.c. circuit in which i (in the 1–7 ampere range) is independent of changes in e. The e-i characteristics are taken for copper electrodes in nitrogen up to 1275 atmospheres pressure, with the result that e increases two times at p=100 atmos. and five times for p=1000 atmos. The pressure effect in helium is similar to nitrogen. Attempts to obtain measurements in hydrogen showed a striking instability of the hydrogen arc at high pressure.