bluuebunny/crossref_metadata_2025 huggingface dataset:
Ground observations of a strong dust storm in Beijing in March 2002
Authors: Zhang Renjian , Arimoto Richard , An Junling , Yabuki Sadayo , Sun Jianhua
Published: March 2005

On 20 March 2002, one of the most intense dust storms of the last decade struck Beijing: the total suspended particle (TSP) mass concentrations during the event reached 12 mg/m3 and the visibility was reduced to less than 200 m. Variations in meteorological conditions in the boundary layer were monitored during the event, and changes in the physical properties and chemical composition of the aerosol also were studied. The dust storm was accompanied by a sharp and distinct increase in wind speed, a decrease in relative humidity, and increased mixing in the boundary layer due to turbulence. Back trajectory analysis and meteorological analysis showed that the main sources of dust particles that affected Beijing were most likely in southern Mongolia and the western part of Inner Mongolia, China. The amounts of Mg, Al, K, Ca, Ti, V, Cr, Mn, and Fe relative to one another were similar for the dust storm and nondust storm samples, and these elements occurred in near‐crustal proportions. In contrast, both the concentrations and enrichments relative to the crustal reference material for other elements, such as Se, Ni, Pb, Br, and Cu, were much higher during the dust storm than before or afterward. These elements, which are often associated with pollution emissions, apparently originated from distant sources upstream as well as from local sources in Beijing. Even though their enrichments were lower during the dust event, the concentrations of S, Zn, and Cl during the dust storm were higher than in the nondust periods; these results are further evidence that dusty air often contains higher levels of pollutants than nondusty air.
Simulations of midlatitude frontal clouds by single‐column and cloud‐resolving models during the Atmospheric Radiation Measurement March 2000 cloud intensive operational period
Authors: Xie Shaocheng , Zhang Minghua , Branson Mark , Cederwall Richard T. , Del Genio Anthony D. , Eitzen Zachary A. , Ghan Steven J. , Iacobellis Sam F. , Johnson Karen L. , Khairoutdinov Marat , Klein Stephen A. , Krueger Steven K. , Lin Wuyin , Lohmann Ulrike , Miller Mark A. , Randall David A. , Somerville Richard C. J. , Sud Yogesh C. , Walker Gregory K. , Wolf Audrey , Wu Xiaoqing , Xu Kuan‐Man , Yio J. John , Zhang Guang , Zhang Junhua
Published: March 2005

This study quantitatively evaluates the overall performance of nine single‐column models (SCMs) and four cloud‐resolving models (CRMs) in simulating a strong midlatitude frontal cloud system taken from the spring 2000 Cloud Intensive Observational Period at the Atmospheric Radiation Measurement (ARM) Southern Great Plains site. The evaluation data are an analysis product of constrained variational analysis of the ARM observations and the cloud data collected from the ARM ground active remote sensors (i.e., cloud radar, lidar, and laser ceilometers) and satellite retrievals. Both the selected SCMs and CRMs can typically capture the bulk characteristics of the frontal system and the frontal precipitation. However, there are significant differences in detailed structures of the frontal clouds. Both CRMs and SCMs overestimate high thin cirrus clouds before the main frontal passage. During the passage of a front with strong upward motion, CRMs underestimate middle and low clouds while SCMs overestimate clouds at the levels above 765 hPa. All CRMs and some SCMs also underestimated the middle clouds after the frontal passage. There are also large differences in the model simulations of cloud condensates owing to differences in parameterizations; however, the differences among intercompared models are smaller in the CRMs than the SCMs. In general, the CRM‐simulated cloud water and ice are comparable with observations, while most SCMs underestimated cloud water. SCMs show huge biases varying from large overestimates to equally large underestimates of cloud ice. Many of these model biases could be traced to the lack of subgrid‐scale dynamical structure in the applied forcing fields and the lack of organized mesoscale hydrometeor advections. Other potential reasons for these model errors are also discussed in the paper.
Vertical distribution of Saharan dust over Rome (Italy): Comparison between 3‐year model predictions and lidar soundings
Authors: Kishcha P. , Barnaba F. , Gobbi G. P. , Alpert P. , Shtivelman A. , Krichak S. O. , Joseph J. H.
Published: March 2005

Mineral dust particles loaded into the atmosphere from the Sahara desert represent one major factor affecting the Earth's radiative budget. Regular model‐based forecasts of 3‐D dust fields can be used in order to determine the dust radiative effect in climate models, in spite of the large gaps in observations of dust vertical profiles. In this study, dust forecasts by the Tel Aviv University (TAU) dust prediction system were compared to lidar observations to better evaluate the model's capabilities. The TAU dust model was initially developed at the University of Athens and later modified at Tel Aviv University. Dust forecasts are initialized with the aid of the Total Ozone Mapping Spectrometer aerosol index (TOMS AI) measurements. The lidar soundings employed were collected at the outskirts of Rome, Italy (41.84°N, 12.64°E) during the high–dust activity season from March to June of the years 2001, 2002, and 2003. The lidar vertical profiles collected in the presence of dust were used for obtaining statistically significant reference parameters of dust layers over Rome and for model versus lidar comparison. The Barnaba and Gobbi (2001) approach was used in the current study to derive height‐resolved dust volumes from lidar measurements of backscatter. Close inspection of the juxtaposed vertical profiles, obtained from lidar and model data near Rome, indicates that the majority (67%) of the cases under investigation can be classified as good or acceptable forecasts of the dust vertical distribution. A more quantitative comparison shows that the model predictions are mainly accurate in the middle part of dust layers. This is supported by high correlation (0.85) between lidar and model data for forecast dust volumes greater than the threshold of 1 × 10−12 cm3/cm3. In general, however, the model tends to underestimate the lidar‐derived dust volume profiles. The effect of clouds in the TOMS detection of AI is supposed to be the main factor responsible for this effect. Moreover, some model assumptions on dust sources and particle size and the accuracy of model‐simulated meteorological parameters are also likely to affect the dust forecast quality.
Is yeast on its way to evolving tRNA editing?
Authors: Schuster Jens , Betat Heike , Mörl Mario
Published: March 2005

In human mitochondria, genes for tRNATyr and tRNACys overlap by a single nucleotide. From polycistronic precursors, a 3′‐truncated upstream tRNATyr is released, missing the overlapping position. A subsequent editing reaction restores this position. Similar mitochondrial tRNA gene overlaps exist in all metazoans, but not in organisms such as yeast or Escherichia coli. Therefore, we asked whether tRNA overlaps are processed in these organisms. Corresponding constructs were introduced and transcripts tested for processing and editing in E. coli and yeast. E. coli produces only one functional tRNA from these precursors, indicating that tRNA overlaps are incompatible with its processing pathway. In contrast, yeast processes overlapping tRNAs similar to human mitochondria, releasing a 3′‐truncated upstream tRNA. This tRNA is restored in an editing‐like event, although yeast does not carry a corresponding endogenous editing substrate. These findings support the hypothesis of the evolution of editing by recruitment of a pre‐existing and promiscuous editing enzyme.
Live attenuated polio vaccine and the risk of intussusception
Authors: Jick Hershel , Vasilakis‐Scaramozza Catherine , Jick Susan S.
Published: March 2005

Aims  Since suspicion has been raised that administration of an oral live attenuated rotavirus vaccine may increase the risk of intussusception in young children, there has been concern about the possible effects of oral polio vaccine. The aim of the study was to evaluate the relationship between oral attenuated polio vaccine and intussusception in children below the age of 1 year.

Methods  We conducted a nested case‐control analysis based on data from the General Practice Research Database which encompassed 133 children who developed documented intussusception during the first year of life and 515 controls.

Results  The time from oral polio vaccine to the index date was similar in cases and controls. Relative risk estimates for intussusception ranged from 0.7 (95% CI 0.2, 2.1) for babies whose last oral polio vaccine was given 29‐35 days before their index date to 1.0 (95% CI 0.4, 2.3) for those whose last oral polio vaccine was given 15‐21 days before their index date (compared with babies vaccinated more than 43 days before their index date).

Conclusions  There is no suggestion that oral polio vaccine increases the risk for intussusception.
Basis function multifield bispectral deconvolution analysis
Authors: Baver D. A. , Terry P. W.
Published: March 2005

A different procedure for calculating linear and nonlinear coefficients of model systems for fully developed turbulence is derived. This procedure can be applied to systems with multiple interacting fields; in the single-field case the linear coefficients consist of mode frequencies and growth rates. This method differs from previous methods in the use of a limited set of functions or basis set from which the nonlinear terms in the turbulence equation are approximated in a series expansion. The algorithm is derived from this assumption using a least squares approach. This approach has been tested on simulations of fully developed two-dimensional turbulence and compared to previous methods. It is able to reconstruct coefficients with several significant figures precision and offers excellent noise rejection capabilities, and is moreover able to operate using tiny data sets compared to those required by previous methods.
Discharge characteristics of plasma display panel with box-shaped apertures in transparent dielectric layer
Authors: Nam Mun-Ho , Choi Sie-Young , Son Seung-Hyun , Kim Young-Mo
Published: March 2005

This article presents an improved front panel structure for an alternating current plasma display panel (ac-PDP) based on a transparent dielectric layer with a box-shaped aperture between the sustain electrodes. The suggested structure can reduce driving voltages than conventional ac-PDPs due to a strong electric field between the sustain electrodes. Experiments were conducted with 10% and 20% Xe contents at a gas pressure of 450Torr, and the results confirmed that the structure with the box-shaped apertures reduced the firing and sustain voltages by about 83.6 and 45.2V than the conventional structure at 10% Xe content, respectively. Also, the proposed structure with a 20% Xe content improved the luminous efficiency and the luminance by about 21.2% and 19.7%, respectively, when compared to a conventional structure with a 10% Xe content at the same sustain voltage. In addition, the discharge and dynamic characteristics show that the suggested structure is very suitable for high-resolution plasma display panel.
Carbon nanotube oscillators toward zeptogram detection
Authors: Nishio Mitsumasa , Sawaya Shintaro , Akita Seiji , Nakayama Yoshikazu
Published: March 2005

We demonstrate an application of a nanotube cantilever for zeptogram-level mass detection. This letter presents a quantitative method to measure the oscillation amplitude of a nanotube cantilever using a focused electron beam of a scanning electron microscope. The quality factor of ∼1000 for the nanotube cantilever is revealed and the resolution of the resonant frequency is achieved to be ∼10Hz, which corresponds to a mass range of less than 100zg at room temperature.
Deep-level optical spectroscopy investigation of N-doped TiO2 films
Authors: Nakano Yoshitaka , Morikawa Takeshi , Ohwaki Takeshi , Taga Yasunori
Published: March 2005

N-doped TiO2 films were deposited on n+-GaN∕Al2O3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 °C in flowing N2 gas. The N-doping concentration was ∼8.8%, as determined from x-ray photoelectron spectroscopy measurements. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at ∼1.18 and ∼2.48eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. Additionally, the 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing by mixing with the O2p valence band.
A Cellular Automata Model for Urban Land-Use Simulation
Authors: Lau Kwok Hung , Kam Booi Hon
Published: March 2005

This paper presents an urban land-use simulation model using cellular automata (CA). In the model urban growth is regarded as the result of a global process underpinned by local actions and land-use change as the joint action of three different effects: attribute, heterogeneity, and gravity. The attribute and heterogeneity effects are regarded as different aspects of a local driving force for change constituted by changing accessibility and other attributes resulting from the interaction of land use and transport at the neighborhood level. The gravity effect is a universal resistance to change as a result of inertia and agglomeration of compatible land uses in the vicinity. To ensure that local actions would lead to global behavior, a multipass, in addition to a single-pass, land-use-allocation algorithm is designed to mimic land-use changes. With metropolitan Melbourne in Australia as a case study, the performance of the model in replicating land-use changes is compared with that of an alternative model developed by using only a distance function. The results of the comparison show that the proposed CA model outperforms the alternative model with only a distance function, confirming the importance of incorporating local attributes in modeling land-use changes.
Encoding Geometric Information in Road Networks Extracted from Binary Images
Authors: Carvalho Rui , Batty Michael
Published: March 2005

The authors discuss recent progress in extracting road networks from digital imagery. We briefly review recent developments in methods for the automatic extraction of road centre line networks and propose a related algorithm aimed at encoding the geometry of road networks with line segments. Our algorithm is inspired by ‘axial lines’, which have been defined as lines of uninterrupted movement within urban streetscapes or buildings. We show that axial lines appear as ridges in isovist fields. These are formed from the maximum diametric lengths of the individual isovists, sometimes called viewsheds, which make up these fields. We present an image-processing technique for the identification of lines from ridges, discuss current strengths and weaknesses of the method, and show how it can be implemented easily and effectively.
Scaling in a Suburban Street
Authors: Crompton Andrew
Published: March 2005

A fractal environment can accommodate more small objects than expected because fresh small spaces come into play as the size of object diminishes. Could the built environment behave like this? To test this hypothesis the number of cars that could be parked in a street was estimated for different sizes of car. The results indicated that scaling does occur. This is as if space can be manufactured from nothing by designing at an appropriate scale. Countries such as Japan which have a small standard of personal space may in fact be larger than they seem on a map.
A Fuzzy Logic System for Visual Evaluation
Authors: Li Siu-Pan , Will Barry F
Published: March 2005

Research has shown that views are an important factor in the overall satisfaction of building occupants, but, because they are qualitative and subjective, views are difficult to assess. This paper presents a new approach to analyzing views using a fuzzy logic methodology, with the aim of assessing the amenity of views. It illustrates the process of constructing a system from data collection and fuzzy rules design, to inference and defuzzification procedures. With the verification of the prediction outcomes, it is shown that the evaluation model can successfully mimic a human's subjective preferences for scenic views. The methodologies and the underlying principles of the evaluation model are explained.
A simple proof of the modular identity for theta series
Authors: Choie Y. , Taguchi Y.
Published: March 2005

We characterize the function spanned by theta series. As an application we derive a simple proof of the modular identity of the theta series.
A hereditarily ℓ₁ subspace of 𝐿₁ without the Schur property
Authors: Popov M.
Published: March 2005

Let

∞
>

p
1

>

p
2

>
⋯
>
1

\infty > p_1 > p_2 > \cdots > 1

. We construct an easily determined

1
1

-symmetric basic sequence in

(

∑

n
=
1

∞

⊕

ℓ

p
n

)

1

\Bigl ( \sum \limits _{n=1}^{\infty } \oplus \ell _{p_n} \Bigr )_1

, which spans a hereditarily

ℓ
1

\ell _1

subspace without the Schur property. An immediate consequence is the existence of hereditarily

ℓ
1

\ell _1

subspaces of

L
1

L_1

without the Schur property.
On decompositions of Banach spaces of continuous functions on Mrówka’s spaces
Authors: Koszmider Piotr
Published: March 2005

It is well known that if

K
K

is infinite compact Hausdorff and scattered (i.e., with no perfect subsets), then the Banach space

C
(
K
)

C(K)

of continuous functions on

K
K

has complemented copies of

c

0

c_{0}

, i.e.,

C
(
K
)
∼

c

0

⊕
X
∼

c

0

⊕

c

0

⊕
X
∼

c

0

⊕
C
(
K
)

C(K)\sim c_{0} \oplus X\sim c_{0}\oplus c_{0} \oplus X\sim c_{0}\oplus C(K)

. We address the question if this could be the only type of decompositions of

C
(
K
)
≁

c

0

C(K)\not \sim c_{0}

into infinite-dimensional summands for

K
K

infinite, scattered. Making a special set-theoretic assumption such as the continuum hypothesis or Martin’s axiom we construct an example of Mrówka’s space (i.e., obtained from an almost disjoint family of sets of positive integers) which answers positively the above question.
Roles of Polymerization Dynamics, Opposed Motors, and a Tensile Element in Governing the Length ofXenopusExtract Meiotic Spindles
Authors: Mitchison T. J. , Maddox P. , Gaetz J. , Groen A. , Shirasu M. , Desai A. , Salmon E. D. , Kapoor T. M.
Published: March 2005

Metaphase spindles assemble to a steady state in length by mechanisms that involve microtubule dynamics and motor proteins, but they are incompletely understood. We found that Xenopus extract spindles recapitulate the length of egg meiosis II spindles, by using mechanisms intrinsic to the spindle. To probe these mechanisms, we perturbed microtubule polymerization dynamics and opposed motor proteins and measured effects on spindle morphology and dynamics. Microtubules were stabilized by hexylene glycol and inhibition of the catastrophe factor mitotic centromere-associated kinesin (MCAK) (a kinesin 13, previously called XKCM) and destabilized by depolymerizing drugs. The opposed motors Eg5 and dynein were inhibited separately and together. Our results are consistent with important roles for polymerization dynamics in regulating spindle length, and for opposed motors in regulating the relative stability of bipolar versus monopolar organization. The response to microtubule destabilization suggests that an unidentified tensile element acts in parallel with these conventional factors, generating spindle shortening force.
Alterations in tissue aerobic capacity may play a role in premigratory fattening in shorebirds
Authors: Selman Colin , Evans Peter R
Published: March 2005

Migratory shorebirds show regulated seasonal increases in body mass (BM) even in captivity, consisting primarily, but not exclusively, of fat. We examined whether captive red knot (Calidris canutus) exhibited seasonal alterations in mitochondrial volume (liver, pectoral muscle) and/or succinate dehydrogenase (SDH) activity (liver, pectoral muscle, heart, small intestine) during three distinct life-cycle stages: stable BM, spring peak in BM, and as BM rapidly declined after the spring peak. Mitochondrial volume in liver and pectoral muscle and SDH activity in liver and heart did not alter with life-cycle stage. However, red knot undergoing premigratory fattening exhibited significantly lower pectoral muscle SDH activity in concert with significantly elevated activity in the small intestine compared with the other two time-points, suggesting that tissue metabolic rate alters with life-cycle stage. The increased intestinal SDH activity may indicate an elevation in energy assimilation at a time when intestine hypertrophy occurs, thus maximizing BM increase prior to putative migration. The concomitant decrease in pectoral muscle activity may act to reduce overall metabolic rate, or at least help counter the elevation in intestinal mass-specific metabolic rate. Both tissues hypertrophy prior to migration in wild red knot, but hypertrophy of the intestine precedes that of pectoral muscle. Indeed, it appears that the intestinal mass undergoes atrophy by the time pectoral muscle hypertrophy occurs in wild red knot. Thus, physiological adjustments in tissue metabolism may be an important factor in the life-history strategies of migrating shorebirds.
The Representation of Jews and of Anti‐Semitism in Joseph Roth's Early Journalism
Authors: Horrocks David
Published: March 2005

Within the vast range of topics covered by Joseph Roth in his early journalism, portrayals of Jews and of anti‐Semitism are not especially prominent. However, they repay analysis as examples of how a writer, without revealing his own Jewish origins, chooses to represent such subjects. Whether reporting on currency speculators in Vienna, an orthodox Jewish community in Hungary, or poor Jewish refugees from the East in Berlin, Roth adopts similar strategies. Initially seeming to confirm widespread prejudices about ‘Ostjuden’, he eventually contrives to subvert them. Portraits of assimilated, middle‐class Jews are less frequent in Roth's work, but articles on Walter Rathenau and the financier Louis Hagen provide an interesting contrast in content, whilst also containing more complex political sub‐texts. Where anti‐Semitism is concerned, Roth proves to be a prescient critic of right‐wing ‘völkisch’ movements operating under the sign of the swastika. Here his main weapon is irony; his major strategy one of turning the anti‐Semites’ arguments back on themselves, thus reducing them to the absurd. Roth's campaign against anti‐Semitism is not, however, motivated by any merely partisan Jewish concern. Rather, as scathing articles on other forms of racial prejudice indicate, it is evidence of a consistent cosmopolitanism on his part.
Some Aspects of German‐Jewish Names
Authors: Livingstone Rodney
Published: March 2005

abstract

Ashkenazi surnames present a bewildering picture, a hotchpotch derived from a variety of languages seemingly without rhyme or reason. But since names are a crucial part of a person's identity it is important to ascertain whether an underlying logic can be discovered. In fact, patterns may be discerned, beginning with the patronyms formed from traditional synagogue names. These were supplemented by the addition of profane names or kinnuyim, many of which refer back to key Biblical texts or the Zohar. By contrast, names based on professions tend to be translated into the different East European languages. Toponyms have become the focus of recent debate as social historians and genealogists explore the actual origins of what had all too readily been assumed to be place names. Name changes arise not just from movement between different countries, but are subject to more direct pressures, chief among them anti‐Semitic sentiment, both in Germany and in Anglophone countries.
Understanding mutualism when there is adaptation to the partner
Authors: DE MAZANCOURT CLAIRE , LOREAU MICHEL , DIECKMANN ULF
Published: March 2005

A mutualism is a mutually beneficial interaction between individuals of two species. Here we show that the degree of benefit resulting from an interaction depends on whether adaptation within the mutualism is considered.

A species’proximate responsemeasures the short‐term effect of addition or removal of the partner species, without allowing for any adaptation. We define aproximate mutualismas an interaction in which removal of each partner results in a decreased performance of the other, i.e. both species show a positive proximate response to the presence of the partner.

A proximate mutualism might, however, only reflect evolved dependence (i.e. the species has lost its ability to perform well without the partner). Some authors therefore insist on an ultimate criterion, regardless of the use of proximate responses in almost all empirical studies.

A species’ultimate responsemeasures the long‐term effect of adding or removing the partner species, thus allowing the focal species to adapt. In anultimate mutualismneither partner could ever have performed as well without the other. In other words, a mutualism is called ultimate if both species show a positive ultimate response to the presence of the partner. Despite the conceptual attractiveness of this definition, ultimate responses are difficult to measure, rendering its use operationally problematic.

Mutualistic evolution, the evolution of a trait that is costly to the bearer but beneficial to its partner, is not, paradoxically, a necessary consequence of either proximate or ultimate mutualism. Another counterintuitive result is that even obligate mutualisms are not necessarily ultimate interactions.

We conclude that the proximate response is the only workable criterion for mutualism. Our understanding of mutualism, however, requires further evaluation of how evolved dependence may be responsible for such responses.

These concepts clarify the ongoing debate about whether plant–herbivore interactions can be considered as mutualistic.

This is not a semantic case of hair splitting: naïve aspects in current views of mutualism need revision. In most, if not all, interactions now considered as mutualisms, some of the measured benefits are likely to result from evolved dependence, rather than what we would like to consider as ultimate benefits.
Spartina alterniflora genotype influences facilitation and suppression of high marsh species colonizing an early successional salt marsh
Authors: PROFFITT C. EDWARD , CHIASSON REBECCA L. , OWENS ALAINA B. , EDWARDS KEITH R. , TRAVIS STEVEN E.
Published: March 2005

Genetically based phenotypic and ecotypic variation in a dominant plant species can influence ecological functions and patterns of recruitment by other species in plant communities. However, the nature and degree of importance of genotypic differences is poorly understood in most systems.

The dominant salt marsh species, Spartina alterniflora, is known to induce facilitative and competitive effects in different plant species, and the outcomes of interactions can be affected by nutrients and flooding stress. Clonal genotypes, which maintained their different plant architecture phenotypes throughout 31 months of a field experiment, underwent considerable genet‐specific senescence in their centres over the last 12 months.

Different clonal genotypes and different locations (robust edges vs. senescent centres) permitted significantly different levels of light penetration of the canopy (14.8–77.6%), thus establishing spatial heterogeneity for this important environmental factor.

S. alterniflora clonal genotype influenced the degree of suppression of the previously dominant Salicornia bigelovii as well as facilitation of recruitment and growth by other plant species. Aster subulatus and Atriplex patula performed better in Spartina clone centres, and experienced reduced growth in Salicornia‐dominated areas.

Four other high marsh species (Borrichia frutescens, Aster tenuifolius, Iva frutescens and Limonium carolinianum) colonized only into Spartina clones but not into the Salicornia‐dominated area.

These results suggest that differences in clone size, centre senescence, stem density, height, total stem length and biomass in different genotypes of a dominant marsh plant species can influence recruitment and growth of other plant species. The spatial pattern of habitat heterogeneity is, at least in part, dependent on the genotypic diversity, and possibly the genetic diversity, of such foundation species.

We hypothesize that as genotypic diversity increases in populations of a dominant plant species like S. alterniflora, the number and diversity of interactions with other species will increase as well.
Seedling recruitment in a hurricane‐driven tropical forest: light limitation, density‐dependence and the spatial distribution of parent trees
Authors: URIARTE MARÍA , CANHAM CHARLES D. , THOMPSON JILL , ZIMMERMAN JESS K. , BROKAW NICHOLAS
Published: March 2005

We used inverse modelling to parameterize spatially‐explicit seedling recruitment functions for nine canopy tree species in the Luquillo Forest Dynamics Plot (LFDP), Puerto Rico. We modelled the observed spatial variation in seedling recruitment following Hurricane Georges as a function of the potential number of seedlings at a given location (based on local source trees and the potential contribution of parents from outside of the mapped area) and of light levels and density‐dependent mortality during establishment. We adopted the model comparison paradigm and compared the performance of increasingly complex models against a null model that assumes uniform seedling distribution across the plot.

Our data supported a model in which parents must reach a threshold size before any seedling production will occur. Once parents attain that size, the relationship between tree diameter and the number of seedlings produced is fairly flat for the majority of species. These results contradict previous analyses that simply assumed a linear relationship between biomass and seedling production and a uniform size threshold for seedling production across species.

The majority of species tested supported models that included at least one of a bath term (contribution from non‐local trees), conspecific density dependence and light availability after the hurricane. Density dependence shifted the mode of the effective dispersal kernel away from potential parent trees and significantly reduced the number of seedlings established near parent trees. Recruitment from non‐local sources accounted for 6–81% of observed seedling recruitment depending upon the tree species. Light availability appeared to divide species into three groups that showed more successful seedling establishment at low (< 5% of full sun), intermediate or high light levels (> 30% full sun).

Differences between individual species in the importance of local vs. bath recruitment and the intensity of density dependence suggest the existence of distinct recruitment syndromes that go beyond the traditional focus of tropical tree life histories. Understanding these syndromes will provide valuable insights into the spatial distribution of tropical tree species and the maintenance of tropical forest diversity.
Validity of 13C‐phenylalanine breath test to evaluate functional capacity of hepatocyte in patients with liver cirrhosis and acute hepatitis
Authors: Koeda N. , Iwai M. , Kato A. , Suzuki K.
Published: March 2005

Background : No definitive method for quantitative evaluation of hepatic function has as yet been established.

Aim : To investigate whether the 13C‐phenylalanine breath test would be useful for the evaluation of hepatic function in patients with liver cirrhosis and acute hepatitis.

Methods : l‐[1‐13C]‐phenylalanine was administered orally in a dose of 100 mg to 25 patients with liver cirrhosis, 22 patients with acute hepatitis and 10 healthy subjects. The relationships of the cumulative excretion with the 13C‐%dose/h, blood biochemical parameters and asialoscintigraphy were investigated.

Results : In liver cirrhosis patients, the cumulative excretion showed correlations with hepatic function tests, asialoscintigraphy, clinical stage and portal hypertension. In acute hepatitis patients, the cumulative excretion showed correlations with hepatic function tests. There were positive correlations between the cumulative excretion and the 13C‐%dose/h at 20 min (Phe20) and 13C‐%dose/h at 30 min (Phe30) in liver cirrhosis and acute hepatitis patients. Multiple regression analysis demonstrated that total bilirubin, total cholesterol and absence of varices were independent determinants of cumulative excretion in liver cirrhosis patients and prothrombin time in acute hepatitis patients.

Conclusion : The 13C‐phenylalanine breath test may allow hepatic function to be evaluated non‐invasively in liver cirrhosis and acute hepatitis patients, and the Phe20 and Phe30 may be useful for determination of function at a single time‐point.
Anti‐Saccharomyces cerevisiae and perinuclear anti‐neutrophil cytoplasmic antibodies in coeliac disease before and after gluten‐free diet
Authors: Granito A. , Zauli D. , Muratori P. , Muratori L. , Grassi A. , Bortolotti R. , Petrolini N. , Veronesi L. , Gionchetti P. , Bianchi F. B. , Volta U.
Published: March 2005

Background : Anti‐Saccharomyces cerevisiae and perinuclear anti‐neutrophil cytoplasmic autoantibodies are markers of Crohn's disease and ulcerative colitis respectively.

Aim : To determine the prevalence of anti‐S. cerevisiae and perinuclear anti‐neutrophil cytoplasmic autoantibodies in a large series of coeliac disease patients before and after gluten free diet, and to correlate anti‐S. cerevisiae‐positivity with intestinal mucosal damage.

Methods : One hundred and five consecutive coeliac disease patients and 141 controls (22 ulcerative colitis, 24 Crohn's disease, 30 primary sclerosing cholangitis, 15 postenteritis syndrome, 50 blood donors) were tested for anti‐S. cerevisiae by enzyme‐linked immunosorbent assay and for perinuclear anti‐neutrophil cytoplasmic autoantibodies by indirect immunofluorescence.

Results : In coeliac disease anti‐S. cerevisiae (immunoglobulin G and/or immunoglobulin A) were slightly less frequent (59%) than in Crohn's disease (75%, P = 0.16) and significantly more frequent than in ulcerative colitis (27%), primary sclerosing cholangitis (30%), postenteritis syndrome (26%) and blood donors (4%) (P = 0.009, P = 0.0002, P = 0.025, P < 0.0001). No correlation was found between anti‐S. cerevisiae and degree of mucosal damage. Perinuclear anti‐neutrophil cytoplasmic autoantibodies were detected only in one coeliac. After gluten free diet the disappearance of anti‐S. cerevisiae‐immunoglobulin A (93%) was more frequent than that of immunoglobulin G (17%, P = 0.0001); perinuclear anti‐neutrophil cytoplasmic autoantibodies disappeared in the only coeliac positive at diagnosis.

Conclusion : More than half of untreated coeliacs are anti‐S. cerevisiae‐positive irrespective of the severity of mucosal damage. Differently from immunoglobulin A, anti‐S. cerevisiae‐immunoglobulin G persisted in more than 80% after gluten free diet. The high prevalence of anti‐S. cerevisiae in coeliac disease suggests that they may be the effect of a non‐specific immune response in course of chronic small bowel disease.
Risk factors for gastro‐oesophageal reflux disease symptoms: a community study
Authors: Mohammed I. , Nightingale P. , Trudgill N. J.
Published: March 2005

Aim:  To examine the prevalence of gastro‐oesophageal reflux disease symptoms and potential risk factors among community subjects.

Methods:  A questionnaire was sent to 4000 subjects, stratified by age, gender and ethnicity to be representative of the local population. Gastro‐oesophageal reflux disease symptoms were defined as at least weekly heartburn or acid regurgitation.

Results:  2231 responded (59%), 691 refused to participate and seven were incomplete. 1533 (41%) were evaluable (637 male, mean age 51 years, range: 20–80). The prevalence of gastro‐oesophageal reflux disease symptoms was 21%. Smoking, excess alcohol, irritable bowel syndrome, increasing body mass index, a family history of upper gastrointestinal disease, increasing Townsend deprivation index, anticholinergic drugs (all P < 0.0001), weight gain, antidepressant drugs, inhaled bronchodilators, no educational attainment (all P < 0.01), south Asian origin (P = 0.02) and manual work (P < 0.05) were associated with gastro‐oesophageal reflux disease symptoms. Multivariate logistic regression revealed increasing body mass index, a family history of upper gastrointestinal disease, irritable bowel syndrome, south Asian origin (all P < 0.0001), smoking, excess alcohol, no educational attainment and anticholinergic drugs (all P < 0.01) were independently associated with gastro‐oesophageal reflux disease symptoms.

Conclusions:  Frequent gastro‐oesophageal reflux disease symptoms affect 21% of the population. Increasing body mass index, a family history of upper gastrointestinal disease, irritable bowel syndrome, south Asian origin, smoking, excess alcohol, social deprivation and anticholinergic drugs are independently associated with gastro‐oesophageal reflux disease symptoms.
Novel missense mutations, GCC [Ala306]– > GTC [Val] and ACG [Thr318]– > CCG [Pro], in the CYP11B1 gene cause steroid 11β‐hydroxylase deficiency in the Chinese
Authors: Lee Hsien‐Hsiung , Won Ging‐Shing , Chao Hsiang‐Tai , Lee Yann‐Jinn , Chung Bon‐chu
Published: March 2005

Objective  Steroid 11β‐hydroxylase (CYP11B1) deficiency, an autosomal recessive inherited disease, accounts for 5–8% of congenital adrenal hyperplasia (CAH). It is mainly caused by mutations of nucleotide substitutions in the coding region.

Patients and Methods  The study reports on a 9‐year‐old Chinese boy who presented with a bone age of 16 years, an enlarged penis, an accelerated growth rate since early childhood and hypertension (160–170/100–110 mmHg) for 3 years. Because it shares 95% sequence homology with aldosterone synthetase (CYP11B2), we developed gene‐specific primers for differential PCR amplification of the CYP11B1 gene. The secondary PCR products of nine exons of the CYP11B1 gene were then subjected to single‐strand conformation polymorphism (SSCP) analysis and DNA sequencing. The serum hormone levels were also determined.

Results  We found that the boy diagnosed with CAH due to 11β‐hydroxylase deficiency carried mutations of A306V (GCC– > GTC) and T318P (ACG– > CCG) in two respective chromosomes. The hormone assay showed that the 11‐deoxycortisol level was higher (667 nmol/l) than normal and was further increased after ACTH stimulation (1206 nmol/l).

Conclusions  These two mutations have not previously been described in the CYP11B1 gene. The discovery of these two novel mutations increases our knowledge of CAH caused by 11β‐hydroxylase deficiency.
Effects of seed size, inbreeding and maternal sex on offspring fitness in gynodioecious Plantago coronopus
Authors: KOELEWIJN HANS PETER , VAN DAMME JOS M. M.
Published: March 2005

Male steriles (MS) must have a fitness advantage relative to hermaphrodites (H) if they are to be maintained in gynodioecious species. We report experiments in which we disentangle the relative contributions of seed size, inbreeding and maternal sex to the fitness advantage of male steriles in Plantago coronopus L.

Seed size effects were observed throughout growth experiments in the glasshouse and were reflected in all biomass measurements. In the field, seed size effects resulted in a fourfold increase in standardized seed production per initial buried seed after 2 years between small (mean weight = 0.13 mg) and large (0.20 mg) seeds.

Inbreeding depression, calculated from seed to seed was δ = 0.37 after one generation of selfing and δ = 0.93 after the second generation of selfing. Regression of log(1 − δ) on inbreeding level suggested synergistic epistasis in fitness.

Even after taking into account the effects of seed size and inbreeding level, the offspring of a male sterile mother had a 16% advantage over a hermaphrodite, but this disappeared when the progeny sex ratio (the ratio of MS : H individuals among the offspring) was taken into account.

In the field, offspring of large seeds had both a higher overall incidence of flowering, and a higher probability of flowering in their first year, thus generating an extra cohort of individuals. The high inbreeding depression in fitness after two generations of selfing was also due to a very low incidence of flowering among the S2 individuals. Flowering probability therefore appears to be a critical trait in this system.

In the field, the contributions of seed size variation (15%) and inbreeding (9%) combine with 48% higher seed production to give a total fitness advantage of 70% of male steriles relative to hermaphrodites. This is probably sufficient for maintenance of gynodioecy under nuclear‐cytoplasmic inheritance of male sterility.

Both inbreeding effects (as a consequence of the sexual system) and pleiotropic effects (of the genes coding for male sterility) play a role in the maintenance of gynodioecy in this species, with an apparently greater role for the latter.
Distribution of Corticotropin‐Releasing Factor Binding Protein‐Immunoreactivity in the Rat Hypothalamus: Association With Corticotropin‐Releasing Factor‐, Urocortin 1‐ and Vimentin‐Immunoreactive Fibres
Authors: Henry B. A. , Lightman S. L. , Lowry C. A.
Published: March 2005

Corticotropin‐releasing factor binding protein (CRF‐BP) is a 37‐kDa protein with high affinity binding sites for both corticotropin‐releasing factor (CRF) and urocortin 1. Previous studies have examined the distribution of CRF‐BP mRNA and peptide within the central nervous system. Due to the predominant cortical localisation, very little is known about CRF‐BP in subcortical structures including the hypothalamus. The present study employed immunohistochemistry to characterise the distribution of CRF‐BP‐like‐immunoreactive (‐ir) cells and fibres in the rat hypothalamus. Bipolar and multipolar CRF‐BP‐ir neurones were scattered throughout the rostro‐caudal extent of the hypothalamus. Distinct clusters of CRF‐BP‐ir neurones were identified in the anterior and posterior parvocellular and dorsal cap subdivisions of the paraventricular nucleus (PVN), as well as in the dorsal hypothalamic area, dorsomedial hypothalamic nucleus (DMN), ventral premammillary nucleus and zona incerta. CRF‐BP‐ir fibres extending from the third ventricle were found in the mediobasal hypothalamus and within the arcuate nucleus‐median eminence region. Double immunostaining together with confocal microscopy demonstrated that the CRF‐BP‐immunostained fibres within the mediobasal hypothalamus coincided with vimentin immunostaining indicating that CRF‐BP‐ir is present within tanycytes. To define the relationship between CRF‐BP‐ir cells and endogenous ligands for CRF‐BP, double immunohistochemistry was performed to examine possible sites within the hypothalamus where CRF‐ or urocortin 1‐ir fibres innervate regions that contain CRF‐BP‐ir cell bodies. CRF‐BP‐ir cell bodies typically coincided with dense CRF‐ir, but not urocortin 1‐ir fibre innervation. CRF‐ir fibre innervation was moderate to high within the anterior and posterior parvocellular subdivisions of the PVN, the dorsal cap of the PVN, DMN and the zona incerta; all regions that contained CRF‐BP‐ir cell populations. These studies demonstrate that, within the hypothalamus, CRF‐BP‐ir cells and fibres are concentrated within a circuitry known to be involved in mediating neuroendocrine and autonomic responses to stress.
Progesterone Can Block the Preovulatory Gonadotropin‐Releasing Hormone/Luteinising Hormone Surge in the Ewe by a Direct Inhibitory Action on Oestradiol‐Responsive Cells within the Hypothalamus
Authors: Richter T. A. , Robinson J. E. , Lozano J. M. , Evans N. P.
Published: March 2005

Elevated oestradiol concentrations during the follicular phase stimulate a surge in gonadotropin‐releasing hormone (GnRH) and luteinising hormone (LH) concentrations, which leads to ovulation. Progesterone can block the oestradiol‐induced GnRH/LH surge, but the mechanism that is involved is unclear. We examined the effect of progesterone on oestradiol‐induced activation of cells within the ovine hypothalamus/preoptic area (POA) to determine: (i) in which regions progesterone acts to block the GnRH/LH surge and (ii) whether progesterone directly or indirectly prevents activation of oestradiol‐responsive cells. Cellular activation was assessed by measuring the number of cells that expressed Fos (an immediate early gene). Exposure to increased oestradiol concentrations in the absence of progesterone (which normally stimulates a LH surge) did not cause any region‐specific changes in hypothalamic Fos expression during the activation stage of the LH surge‐induction process (Experiment 1). The same treatment significantly increased cellular activation within the POA, lateral septum (LS), and arcuate nucleus at the time of surge onset (Experiment 2). Concurrent exposure to increased oestradiol and progesterone concentrations during the activation stage of the surge‐induction process (which normally blocks the LH surge) was associated with significantly reduced cellular activation within the ventromedial hypothalamus and anterior hypothalamic area, relative to the positive controls (oestradiol increment alone) and arcuate nucleus relative to the negative controls (no increment in oestradiol) during the activation stage (Experiment 1). At the time of surge onset (Experiment 2), exposure to progesterone during the activation period prevented the oestradiol‐induced increase in cellular activation that occurred in the POA, LS and arcuate nucleus of the positive controls. These results demonstrated that oestradiol and progesterone induced differential region‐ and time‐specific effects on cellular activation within the regions of the ovine brain that generate the preovulatory GnRH/LH surge. Moreover, the lack of cellular activation within the POA, LS and arcuate nucleus at the time of surge onset in animals exposed to progesterone during the activation stage is consistent with the hypothesis that progesterone can block the preovulatory surge by direct inhibition of oestradiol‐induced cellular activation in these areas.
Hypothalamic STAT Proteins: Regulation of Somatostatin Neurones by Growth Hormone Via STAT5b
Authors: Bennett E. , McGuinness L. , Gevers E. F. , Thomas G. B. , Robinson I. C. A. F. , Davey H. W. , Luckman S. M.
Published: March 2005

Signal transducers and activators of transcription (STATs) are a family of transcription factors linked to class I cytokine receptors. In the present study, we investigated whether their distribution in the hypothalamus reflects the feedback regulation by growth hormone and what role they might play in the functioning of target neurones. We demonstrate that each of the seven known STATs has a distinct distribution in the hypothalamus. Notably, the STAT5 proteins, that are important in growth hormone (GH) and prolactin signalling in peripheral tissues, were expressed in somatostatin neurones of the periventricular nucleus and dopamine neurones of the arcuate nucleus. Because somatostatin neurones are regulated by feedback from circulating GH, we investigated the importance of STAT5 in these neurones. We demonstrate that STAT5b protein expression, similar to somatostatin mRNA, is sexually dimorphic in the periventricular nucleus of rats and mice. Furthermore, chronic infusion of male dwarf rats with GH increased the expression of STAT5b, while a single injection of GH into similar rats induced the phosphorylation of STAT5 proteins. The cellular abundance of somatostatin mRNA in STAT5b‐deficient mice was significantly reduced in the periventricular nucleus, effectively reducing the sexually dimorphic expression. These results are consistent with the hypothesis that STAT5 proteins are involved in the feedback regulation of somatostatin neurones by GH, and that these neurones may respond to patterned GH secretion to reinforce sexual dimorphism in the GH axis.