bluuebunny/crossref_metadata_2025 huggingface dataset:
Solvent‐induced switching of the macromolecular helicity of poly[(4‐carboxyphenyl)acetylene] induced by a single chiral amino alcohol
Authors: Maeda Katsuhiro , Morino Kazuhide , Yashima Eiji
Published: October 2003

Cis–transoidal poly[(4‐carboxyphenyl)acetylene] (poly‐1) complexed with optically active amines and amino alcohols showed an induced circular dichroism (ICD) in the ultraviolet–visible region because of a predominantly one‐handed helix formation in water and in dimethyl sulfoxide (DMSO). The Cotton effect signs of the poly‐1/chiral amino alcohol complexes were inverted in the presence of water, whereas the ICD pattern of the poly‐1/chiral amine complexes showed no change, regardless of the water content. These results demonstrated that the helix sense of poly‐1 induced by optically active amino alcohols through noncovalent acid–base interactions could be switched by changes in the solvent ratio in the DMSO–water mixtures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3625–3631, 2003
Transition‐metal‐templated synthesis of rotaxanes and catenanes: From small molecules to polymers
Authors: Kern Jean‐Marc , Sauvage Jean‐Pierre , Bidan Gerard , Divisia‐Blohorn Bernadette
Published: October 2003

This article provides an overview of the fundamental principles of the synthesis of metallocatenanes and metallorotaxanes. It also describes the synthesis and properties of electronic conducting polymers—polypyrrole and polythiophene—built around metallocatenanes and metallorotaxanes. The particular properties of this new class of polymers, including the possibility of transmetallation reactions being performed with them and the observation of electronic coupling between the metal centers and the conducting matrix, are discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3470–3477, 2003
Amphiphilic and hydrophobic surface patterns generated from hyperbranched fluoropolymer/linear polymer networks: Minimally adhesive coatings via the crosslinking of hyperbranched fluoropolymers
Authors: Gan Daoji , Mueller Anja , Wooley Karen L.
Published: October 2003

Hyperbranched fluoropolymers (HBFPs), based on benzyl ether linkages and having a large number of pentafluorophenyl chain ends, were crosslinked by a reaction with diamino‐terminated poly(ethylene glycol) (PEG) or diamino‐terminated poly(dimethyl siloxane) (PDMS) to form hyperbranched–linear copolymer networks of different compositions, structures, and properties. The crosslinking reactions involved the nucleophilic aromatic substitution of the pentafluorophenyl para‐fluorines of HBFP by the amine functionalities of the respective telechelic linear segments. The contact angles, differential scanning calorimetry, thermogravimetric analysis, tensile measurements, and atomic force microscopy (AFM) were used to characterize the resulting network film samples. The surface wettability of the crosslinked materials was affected by the nature and amount of the linear polymer crosslinking agent employed. Amphiphilic polymer networks were formed by the incorporation of diamino‐terminated PEG as a crosslinker, whereas diamino‐terminated PDMS produced polymer networks of a hydrophobic character. The mechanical properties improved upon crosslinking, as measured by tensile testing. The mechanical integrity of the films was also found to improve upon crosslinking, as measured by AFM machining protocols. The AFM images revealed topographical morphologies that appeared to be the result of phase segregation of HBFP from PEG or PDMS; the dimensions of the phase‐segregated domains were dependent on the stoichiometry of HBFP to the linear polymer and the thickness of the coating. As the content of PEG increased, fouling by human fibrinogen, used as a model protein, decreased. Further studies are in progress to determine the effects of the surface composition, morphology, and topography on the biofouling characteristics. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3531–3540, 2003
Some of Sam Greenhouse's contributions to statistical methods
Authors: Gail Mitchell H.
Published: October 2003

I briefly survey some areas of Sam Greenhouse's contributions to statistical methods before focusing on three examples. These examples illustrate Sam's ability to identify problems of practical importance and to make valuable contributions to their solutions. Many of his papers continue to provide important guidance and insight because he dealt with issues of enduring practical importance. Published in 2003 by John Wiley & Sons, Ltd.
The use of the ‘reverse Cornfield inequality’ to assess the sensitivity of a non‐significant association to an omitted variable
Authors: Yu Binbing , Gastwirth Joseph L.
Published: October 2003

Unlike randomized experimental studies, investigators do not have control over the treatment assignment in observational studies. Hence, the treated and control (non‐treated) groups may have widely different distributions of unobserved covariates. Thus, if observational data are analysed as if they had arisen from a controlled study, the analyses are subject to potential bias. Sensitivity analysis is a technique for assessing whether the inference drawn from a study could be altered by a moderate ‘imbalance’, between the distribution of the covariates in different groups. In this paper, we examine the sensitivity analysis of the test of proportions in 2 × 2 tables from a new perspective: ‘could a non‐significant result have occurred because the treated group has a higher prevalence of an unobserved risk factor?’. The study was motivated by an analysis of the studies concerning with the possible effect of spermicide use on birth defects that were cited in a legal decision. Copyright © 2003 John Wiley & Sons, Ltd.
Estimating population size and duplication rates when records cannot be linked
Authors: Laska Eugene M. , Meisner Morris , Wanderling Joseph , Siegel Carole
Published: October 2003

The capture‐recapture approach to estimating the size of a population is a well‐studied area of statistics. The number of distinct individuals, NA and NB, on each of two lists, A and B, and the number common to both lists, NAB, are used to form an estimate of the binomial probability of being on one of the lists, which then allows an estimate to be made of the size of the population. Critical to the method is an accurate count of NAB. We consider situations in which this count is not available. Such problems arise in a variety of behavioural health contexts in which the need for protection of privacy may prevent sharing identifying information, so it is not possible to specifically match an individual who appears on one list with an individual on the other. Suppose that the birth dates and/or other demographics of individuals on each list are known. We introduce two methods for estimating the duplication rates and the size of the population. Conditioning on the set β of birth dates of those on list B, NA and NB, the maximum likelihood estimators (MLEs) and their variance are derived. The MLEs are based on the proportion of individuals on list A whose birth dates fall in β. This approach is particularly useful if list B itself contains duplicates. The second model utilizes the full sample distribution of the birth dates. We generalize this approach to accommodate multiple demographic characteristics. The approaches are applied to the problem of estimating duplication rates and the population size of veterans who have mental illness in Kings County, NY. The data are lists of those receiving service from the Veterans Administration system and from providers funded or certified by the New York State Office of Mental Health. Copyright © 2003 John Wiley & Sons, Ltd.
Long distance nitrogen air pollution effects on lichens in Europe
Authors: van Herk C. M. , Mathijssen-Spiekman E. A. M. , de Zwart D.
Published: October 2003

The epiphytic lichen flora of 25 European ICP-IM monitoring sites, all situated remote from air pollution sources, was statistically related to measured levels of SO2 in air, NH4+, NO3− and SO42− in precipitation, annual bulk precipitation, and annual average temperature. Significant regression models were calculated for eleven acidophytic species. Several species strong negative correlation with nitrogen compounds. At concentrations as low as 0·3 mg N l−1 in precipitation, a decrease of the probability of occurrence is observed for Bryoria capillaris, B. fuscescens, Cetraria pinastri, Imshaugia aleurites and Usnea hirta. The observed pattern correlations strongly suggests a key role of NH4+ in determining the species occurrence, additional role of NO3− cannot be ruled out. Some species show a distinct response to current of SO2 well. It may be concluded that long distance nitrogen air pollution has strong influence the occurrence of acidophytic lichen species.
A new species of Arctomia from Sichuan Province, China
Authors: Jørgensen P. M.
Published: October 2003

Arctomia teretiuscula sp. nov. (Arctomiaceae) is described from Sichuan Province, China. A minutely coralloid, bryophilous cyanolichen, it is a further example of the biogeographical link between the lichen biotas of the Himalayan region and the Arctic. A key to the three accepted species of Arctomia is provided.
Effective exploration and visualization of geological parameter space
Authors: Boschetti F. , Wijns C. , Moresi L.
Published: October 2003

Inverse modeling returns many solutions apart from the final product. Exploring and visualizing the solution space covered by an inversion leads to a greater understanding of the problem. Our method combines an inversion algorithm with an effective two‐dimensional representation of the multidimensional model parameter space. The analysis of all solutions is done through a visualization technique known as self‐organized mapping, resulting in a simple view of an otherwise complicated problem. A user may infer much about the controlling factors in the model through a few graphical displays of the data.
Denudational and thermal history along a transect across the Lambert Graben, northern Prince Charles Mountains, Antarctica, derived from apatite fission track thermochronology
Authors: Lisker Frank , Brown Roderick , Fabel Derek
Published: October 2003

The denudational history along a transect across the western margin of the Lambert Graben, northern Prince Charles Mountains, East Antarctica, is quantified on the basis of thermal history modeling of apatite fission track data from four vertical profiles. Early Cretaceous paleogeothermal gradients estimated from the fission track data increase from ∼19°C km−1 ∼50 km west of the rift margin to ∼29°C km−1 within the immediate vicinity of the western master fault. Two discrete phases of enhanced denudation during the Phanerozoic are inferred for the western rift margin. The first occurred during the early Paleozoic, with minimum denudation of between 1.6 and 5.0 km, which is broadly coeval with initial rifting and the major period of Permo‐Triassic sedimentation within the Lambert Graben. The formation of the graben was related to the formation of the ancestral Gamburtsev Mountains due to Variscan compression and substantial crustal thickening of the East Antarctic Craton. The second phase of denudation commenced in the Early Cretaceous, with estimated amounts ranging between 1.0 and 4.5 km, generally increasing toward the rift margin, with the maximum total denudation occurring ∼20 km west of the western master fault of the graben. The Early Cretaceous phase of denudation was probably related to tectonic reactivation of the earlier Permo‐Triassic rift during the initial separation of the Indian and Antarctic sector of Gondwana.
Biomass burning in Asia: Annual and seasonal estimates and atmospheric emissions
Authors: Streets D. G. , Yarber K. F. , Woo J.‐H. , Carmichael G. R.
Published: October 2003

Estimates of biomass burning in Asia are developed to facilitate the modeling of Asian and global air quality. A survey of national, regional, and international publications on biomass burning is conducted to yield consensus estimates of “typical” (i.e., non‐year‐specific) estimates of open burning (excluding biofuels). We conclude that 730 Tg of biomass are burned in a typical year from both anthropogenic and natural causes. Forest burning comprises 45% of the total, the burning of crop residues in the field comprises 34%, and 20% comes from the burning of grassland and savanna. China contributes 25% of the total, India 18%, Indonesia 13%, and Myanmar 8%. Regionally, forest burning in Southeast Asia dominates. National, annual totals are converted to daily and monthly estimates at 1° × 1° spatial resolution using distributions based on AVHRR fire counts for 1999–2000. Several adjustment schemes are applied to correct for the deficiencies of AVHRR data, including the use of moving averages, normalization, TOMS Aerosol Index, and masks for dust, clouds, landcover, and other fire sources. Good agreement between the national estimates of biomass burning and adjusted fire counts is obtained (R2= 0.71–0.78). Biomass burning amounts are converted to atmospheric emissions, yielding the following estimates: 0.37 Tg of SO2, 2.8 Tg of NOx, 1100 Tg of CO2, 67 Tg of CO, 3.1 Tg of CH4, 12 Tg of NMVOC, 0.45 Tg of BC, 3.3 Tg of OC, and 0.92 Tg of NH3. Uncertainties in the emission estimates, measured as 95% confidence intervals, range from a low of ±65% for CO2emissions in Japan to a high of ±700% for BC emissions in India.
Structure of Earth's outer radiation belt inferred from long‐term electron flux dynamics
Authors: Vassiliadis D. , Klimas A. J. , Weigel R. S. , Baker D. N. , Rigler E. J. , Kanekal S. G. , Nagai T. , Fung S. F. , Friedel R. W. H. , Cayton T. E.
Published: October 2003

We map the spatial structure of the electron belts over their radial range (L = 1–11 RE) using a total of 25 years of observations by NASA, ISAS, and GPS spacecraft. Correlation analysis reveals significant radial structuring of the outer belt and identifies three regions, while earlier single‐spacecraft studies are used to interpret the results. The central region P1 (L = 4.1–7.5 RE) has a well‐known slow response (2–3 days) most probably due to shear‐hydrodynamic effects of the interplanetary medium, which excite ULF waves at low latitudes. In the innermost region P0 (L = 3.0–4.1 RE) the electron response is rapid (<1 day). It appears related to solar wind ram‐hydrodynamic inputs (compressions) and/or time‐varying interplanetary electric and magnetic fields. Region P2 (L > 7.5 RE) has a much weaker brief response to magnetic field orientation and low interplanetary plasma velocities, anticorrelated with the other two regions. The findings and, in addition, the solar‐cycle modulation of the region size strongly suggest that the solar wind excites nonlinear response modes in the inner magnetosphere which are prototypically revealed in the three regions. Given this spatial variability, the optimal approach to next‐generation modeling and electron storm forecasting may differ considerably for each region.
Towards direct measurement of turbulent vertical fluxes of compounds in atmospheric aerosol particles
Authors: Held A. , Hinz K.‐P. , Trimborn A. , Spengler B. , Klemm O.
Published: October 2003

Vertical fluxes of gaseous and particulate compounds in the planetary boundary layer are mainly established through turbulence. To date, it is a challenge to measure vertical fluxes of particles and, even more, the fluxes of compounds in particulates. The combination of disjunct eddy sampling and time‐of‐flight MS single particle analysis bears the potential to directly measure the turbulent particle flux together with the chemical particle composition. Several obstacles must be overcome before this goal may be achieved. In this paper, we present a statistical procedure, using Monte‐Carlo‐type simulations, to obtain the flux direction of particulate compounds such as nitrate. A first experimental application of this method yielded emission of particulate NO3− from a forest ecosystem on a summer day with a statistical confidence of 89%.
Change in stress directions along the central Denali fault, Alaska after the 2002 earthquake sequence
Authors: Ratchkovski Natalia A.
Published: October 2003

On the basis of earthquake focal mechanisms, the state of stress along the central Denali fault, Alaska system changed after the 2002 earthquake sequence. Before the earthquake sequence, the maximum stress (σ1) was at a 60° angle with the Denali fault west of the point of its maximum curvature, fault‐normal between the fault apex and the Totschunda strand, and at 50° with respect to the Totschunda fault. In the epicentral region, the post‐event σ1 has rotated counter‐clockwise. Along the rest of the rupture zone the sense of rotation is clockwise. The σ1 direction became nearly fault‐normal along the Totschunda strand. Along the central part of the rupture, σ1 is over‐rotated with σ3 being nearly vertical, promoting reverse aftershocks. This could be an indication of dynamic overshoot.
Factors controlling atmospheric fluxes of 7Be and 210Pb in northern Taiwan
Authors: Su Chih‐Chieh , Huh Chih‐An , Lin Fei‐Jen
Published: October 2003

Fluxes of 7Be and 210Pb were continuously monitored at two sites in northern Taiwan during 1996–2001. The time series of both nuclides show seasonality and dependence on precipitation, annual monsoon cycle and episodic events (typhoons and Asian dust storms). Besides, anomalously high 7Be and 210Pb fluxes occurred in 1998, which are most likely caused by enhanced atmospheric convection in the north Pacific resulting from significantly increased SST in the western Pacific warm pool.
Coupled ocean‐atmosphere nested modeling of the Adriatic Sea during winter and spring 2001
Authors: Pullen Julie , Doyle James D. , Hodur Richard , Ogston Andrea , Book Jeffrey W. , Perkins Henry , Signell Richard
Published: October 2003

Realistic simulations of the Adriatic Sea for over 125 days are conducted using the Navy Coastal Ocean Model with atmospheric forcing provided by the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS is a registered trademark of the Naval Research Laboratory (COAMPS™)). In two separate simulations of the Adriatic, a nested 2‐km‐resolution ocean model is forced by the inner (4‐km) and outer (36‐km) nests of the atmospheric model. Two meteorological stations and two acoustic Doppler current profiler observation sites are used to evaluate modeled atmosphere and ocean velocity fields for 28 January–4 June 2001. Modeled/observed correlations of atmospheric 10‐m velocity are greater than 0.85 for both resolution models. Oceanic 5‐ and 25‐m current fluctuations from both simulations generally match the magnitude and orientation of the observations. The 4‐km‐resolution atmospheric model is differentiated from the 36‐km‐resolution model by its ability to resolve the small‐scale flow structures of the “bora” wind and by its better agreement with observed wind velocity statistics. The ocean simulation forced by the 4‐km‐resolution model is distinguished from the one forced by the 36‐km‐resolution model by its ability to reproduce the expected double‐gyre circulation in the northern Adriatic and by its ability to better capture the magnitude and shape of the observed depth‐dependent velocity correlation with wind at the deeper site. Though the 36‐km forced ocean model agrees better with many observed velocity statistics, the 4‐km forced ocean model produces the highest correlations with observations (exceeding 0.78) at subsurface depths that are most strongly correlated with winds.
Europe to Develop New Space Weather Services
Authors: Simpson Sarah
Published: October 2003

The European Space Agency's Space Weather Applications Pilot Project (SWAPP) is testing and coordinating more than 17 new services for European customers.
A comparison of direct measurement and model simulation of total flux of volatile organic compounds from the subsurface to the atmosphere under natural field conditions
Authors: Tillman Fred D. , Choi Jee‐Won , Smith James A.
Published: October 2003

Accurate quantification of natural attenuation of volatile organic compounds (VOCs) in groundwater requires an accounting of all VOC mass‐loss processes, including volatilization into soil gas with ultimate transport to land surface and the atmosphere. This paper compares two methods of estimating VOC flux to the atmosphere. The first method measures VOC flux at land surface using a vertical flux chamber (VFC). The VFC has been shown in a previous laboratory study to reliably measure organic vapor fluxes from soil to the atmosphere that are caused by either gas phase diffusion or a combination of advection plus diffusion [Tillman, 2003]. The second method simulates VOC flux using a transient, one‐dimensional gas flow and transport model incorporating the effects of gas phase diffusion, equilibrium air‐water partitioning of organic vapors, and unsaturated zone airflow caused by atmospheric pressure changes (i.e., barometric pumping). Flux chamber measurements were made concurrently with field data measurements required for the flow and transport model at a trichloroethene (TCE)‐contaminated field site. The two methods of VOC flux estimation provided comparable results in nine sets of field comparisons with the flux chamber estimating a lower flux during most of the time periods. Sensitivity analyses of model input parameters produce upper and lower bounds on best estimate flux simulations. Average VFC measurements fall within these upper and lower bounds of combined parameter values for all nine comparison events. The ease of use, lack of a priori site knowledge and accuracy of the VFC compared with the data‐intensive flow and transport model suggests that direct measurement of VOC flux from the subsurface to the atmosphere at contaminated sites could become routine practice, providing important information to decision makers about the progress of monitored natural attenuation.
Modeling of karst aquifer genesis: Influence of exchange flow
Authors: Bauer Sebastian , Liedl Rudolf , Sauter Martin
Published: October 2003

This paper presents a numerical model study simulating the early karstification of a single conduit embedded in a fissured system. A hybrid continuum‐discrete pipe flow model (CAVE) is used for the modeling. The effects of coupling of the two flow systems on type and duration of early karstification are studied for different boundary conditions. Assuming fixed head boundaries at both ends of the conduit, coupling of the two flow systems via exchange flow between the conduit and the fissured system leads to an enhanced evolution of the conduit. This effect is valid over a wide range of initial conduit diameters, and karstification is accelerated by a factor of about 100 as compared to the case of no exchange flow. Parameter studies reveal the influence of the exchange coefficient and of the hydraulic conductivity of the fissured system on the development time for the conduit. In a second scenario the upstream fixed head boundary is switched to a fixed flow boundary at a specified flow rate during the evolution, limiting the amount of water draining toward the evolving conduit. Depending on the flow rate specified, conduit evolution may be slowed down or greatly impaired if exchange flow is considered.
Laplace transform inversion for late‐time behavior of groundwater flow problems
Authors: Mathias Simon A. , Zimmerman Robert W.
Published: October 2003

Laplace transforms are widely used in solving groundwater flow problems. In the groundwater literature, it has frequently been asserted or assumed that the late‐time behavior is governed by the behavior of the Laplace transform for small values of the Laplace variable. Careful reading of authoritative monographs on Laplace transforms shows that this correspondence does not generally hold. In this article the proper asymptotic formula is reviewed and is applied to the problem of water influx into a slab‐like matrix block in a dual‐porosity medium. In doing so, we clear up a long‐standing discrepancy between the fracture/matrix transfer coefficient that has been calculated by Laplace methods and the coefficient which has been found by applying Fourier methods in the time domain.
Invasibility of plankton food webs along a trophic state gradient
Authors: Lennon Jay T. , Smith Val H. , Dzialowski Andrew R.
Published: October 2003

Biological invasions are becoming more common, yet the majority of introduced exotic species fail to establish viable populations in new environments. Current ecological research suggests that invasion success may be determined by properties of the native ecosystem, such as the supply rate of limiting nutrients (i.e. trophic state). We examined how trophic state influences invasion success by introducing an exotic zooplankter,Daphnia lumholtziinto native plankton communities in a series of experimental mesocosms exposed to a strong nutrient gradient. We predicted that the attributes of nutrient‐enriched communities would increase the likelihood of a successful invasion attempt byD. lumholtzi. Contrary to our original predictions, we found thatD. lumholtziwas often absent from mesocosms that developed under high nutrient supply rates. Instead, the presence ofD. lumholtziwas associated with systems that had low nutrients, low zooplankton biomass, and high zooplankton species diversity. Using generalized estimating equations (GEE) and multivariate species data, we found that the presence–absence ofD. lumholtzicould be explained by variations in zooplankton community structure, which was itself strongly influenced by nutrient supply rate. We argue that the apparent invasion success ofD. lumholtziwas inhibited by the dominance of another cladoceran species,Chydorus sphaericus. These results suggest that the interaction between trophic state and species identity influenced the invasion success of introducedD. lumholtzi.
Responses of moist non‐acidic arctic tundra to altered environment: productivity, biomass, and species richness
Authors: Gough Laura , Hobbie Sarah E.
Published: October 2003

In arctic Alaska, researchers have manipulated air temperature, light availability, and soil nutrient availability in several tundra communities over the past two decades. These communities responded quite differently to the same manipulations, and species responded individualistically within communities and among sites. For example, moist acidic tundra is primarily nitrogen (N)‐limited, whereas wet sedge tundra is primarily phosphorus (P)‐limited, and the magnitude of growth responses varies across sites within communities. Here we report results of four years of manipulated nutrients (N and/or P) and/or air temperature in an understudied, diverse plant community, moist non‐acidic tussock tundra, in northern Alaska. Our goals were to determine which factors limit above‐ground net primary productivity (ANPP) and biomass, how community composition changes may affect ecosystem attributes, and to compare these results with those from other communities to determine their generality.

Although relative abundance of functional groups shifted in several treatments, the only significant change in community‐level ANPP and biomass occurred in plots that received both N and P, driven by an increase in graminoid biomass and production resulting from a positive effect of adding N. There was no difference in community biomass among any other treatments; however, some growth forms and individual species did respond. After four years no one species has come to dominate the treatment plots and species richness has not changed. These results are similar to studies in dry heath, wet sedge, and moist acidic tundra where community biomass had the greatest response to both N and P and warming results were more subtle. Unlike in moist acidic tundra where shrub biomass increased markedly with fertilization, our results suggest that in non‐acidic tundra carbon sequestration in plant biomass will not increase substantially under increased soil nutrient conditions because of the lack of overstory shrub species.
Population consequences of movement decisions in a patchy landscape
Authors: Russell Robin E. , Swihart Robert K. , Feng Zhilan
Published: October 2003

Complex, human‐dominated landscapes provide unique challenges to animals. In landscapes fragmented by human activity, species whose home ranges ordinarily consist of continuous habitat in pristine environments may be forced to forage among multiple smaller habitat patches embedded in an inhospitable environment. Furthermore, foragers often must decide whether to traverse a heterogeneous suite of landscape elements that differ in risk of predation or energetic costs. We modeled population consequences of foraging decisions for animals occupying patches embedded in a heterogeneous landscape. In our simulations, animals were allowed to use three different rules for moving between patches: a) optimal selection resulting from always choosing the least‐cost path; b) random selection of a movement path; and c) probabilistic selection in which path choice was proportional to an animal's probability of survival while traversing the path. The resulting distribution of the population throughout the landscape was dependent on the movement rule used. Least‐cost movement rules (a) produced landscapes that contained the highest average density of consumers per patch. However, optimal movement resulted in an all‐or‐none pattern of occupancy and a coupling of occupied patches into pairs that effectively reduced the population to a set of sub‐populations. Random and probabilistic rules, (b and c), in relatively safe landscapes produced similar average densities and 100% occupancy of patches. However, as the level of risk associated with travel between patches increased, random movement resulted in an all‐or‐none occupancy pattern while occupied patches in probabilistic populations went extinct independently of the other patches. Our results demonstrate strong effects of inter‐patch heterogeneity and movement decisions on population dynamics, and suggest that models investigating the persistence of species in complex landscapes should take into account the effects of the intervening landscape on behavioral decisions affecting animal movements between patches.
Recruitment rates exhibit high elasticity and high temporal variation in populations of a short‐lived perennial herb
Authors: Picó F. Xavier , Quintana‐Ascencio Pedro F. , Menges Eric S. , López‐Barrera Fabiola
Published: October 2003

Empirical studies for different life histories have shown an inverse relationship between elasticity (i.e. the proportional contribution to population growth rate) and temporal variation in vital rates. It is accepted that this relationship indicates the effect of selective pressures in reducing variation in those life‐history traits with a major impact on fitness. In this paper, we sought to determine whether changes in environmental conditions affect the relationship between elasticity of vital rates and their temporal variation, and whether vital rates with simultaneously large elasticity and temporal variation might represent a characteristic life‐history strategy. We used demographic data on 13 populations of the short‐lived Hypericum cumulicola over 5–6 years, in three time‐since‐fire classes. For each population of each time‐since‐fire, we computed the mean matrix over years and its respective elasticity matrix, and the coefficients of variation in matrix entries over study years as an estimate of temporal variability. We found that mean elasticity negatively significantly correlated with temporal variation in vital rates in populations (overall eight out of 13) included in each time‐since‐fire. However, seedling recruitment exhibited both high elasticity and high temporal variation in almost all study populations. These results indicated that (1) the general relationship between elasticity and temporal variation in vital rates was not modified by environmental changes due to time‐since‐fire, and (2) high elasticity and high temporal variation in seedling recruitment in H. cumulicola is a particular trait of the species' life history. After seed survival in the soil seed bank, seedling recruitment represents the most important life‐history trait influencing H. cumulicola population growth rate (and fitness). The high temporal variability in seedling recruitment suggests that this trait is determined by environmental cues, leading to an increase in population size and subsequent replenishment of the seed bank in favorable years.
Melatonin prevents apoptosis and enhances HSP27 mRNA expression induced by heat shock in HL‐60 cells: possible involvement of the MT2 receptor
Authors: Cabrera Javier , Quintana José , Reiter Russel J. , Loro Juan , Cabrera Félix , Estévez Francisco
Published: October 2003

Abstract: Previous studies have reported that melatonin protects cells and tissues against stressful stimuli. In the present study using HL‐60 cells, we show that cells acquire increased resistance to apoptosis normally induced by heat shock when they are incubated with melatonin. This effect of melatonin is saturable at nanomolar concentrations and appears to be mediated by the MT2 subtype melatonin receptor. The high affinity melatonin receptor agonist, 2‐iodomelatonin, reproduced the melatonin effect while it was fully blocked by the selective MT2 antagonist 4‐phenyl‐2‐propionamidotetraline. The melatonin response to heat shock‐induced apoptosis was pertussis toxin sensitive and, interestingly, the non‐selective MT1/MT2 melatonin receptor ligand luzindole was found to display agonistic activity. Furthermore, we provide evidence that melatonin enhanced HSP27 mRNA expression as a result of heat shock – HSP27, is known to play an important role in the defense of cells against apoptosis induced by stressful agents. Together, these results demonstrate that melatonin, likely via receptor mechanisms, interferes with the apoptotic pathway activated by heat shock.
Relationship between salivary melatonin levels and periodontal status in diabetic patients
Authors: Cutando Antonio , Gómez‐Moreno Gerardo , Villalba Juan , Ferrera María José , Escames Germaine , Acuña‐Castroviejo Darío
Published: October 2003

Abstract: Among other functions, melatonin exerts both antioxidative and immunoregulatory roles. The indoleamine is secreted in the saliva, although its role into the mouth is not known. Diabetic patients frequently display oral cavity pathologies such as periodontal disease (PD), an inflammatory disease coursing with an increase in free radical production. Thus, we compared the degree of PD and interleukin‐2 (IL‐2) levels with melatonin concentrations in plasma and saliva of diabetic patients. A total of 43 diabetic patients (20 with type I and 23 with type II diabetes) and 20 age‐ and sex‐matched controls were studied. Dental and medical history of all patients was in accordance with the criteria of the WHO. The periodontal status was evaluated by the Community Periodontal Index (CPI). Plasma and salivary melatonin levels were determined by specific commercial radioimmunoassays, and plasma IL‐2 was measured using a commercial enzyme‐linked immunosorbent assay kit. Diabetic patients had plasma and saliva melatonin levels of 8.98 ± 7.14 and 2.70 ± 2.04 pg/mL, respectively. These values were significantly lower (P < 0.001) than those obtained in plasma and saliva of controls (14.91 ± 4.75 and 4.35 ± 0.98 pg/mL, respectively). Plasma and salivary melatonin concentrations show a biphasic response in diabetic patients. Melatonin decreased in patients with a CPI index of 2, and then increased reaching highest levels in patients with a CPI index of 4. By contrast, IL‐2 levels decreased from CPI index 1 to 4. The results indicate that, in diabetic patients, the presence of a marked impairment of the oral status, as assessed by the CPI index, is accompanied by an increase in plasma and salivary melatonin. The increase in salivary melatonin excretion may have a periodontal protective role.
Urinary 6‐hydroxy‐melatonin‐sulfate excretion and circadian rhythm in patients with restless legs syndrome
Authors: Tribl Gotthard G. , Waldhauser Franz , Sycha Thomas , Auff Eduard , Zeitlhofer Josef
Published: October 2003

Abstract: The precise etiology of the restless legs syndrome (RLS) is unknown. Sensory and motor symptoms of RLS worsen during evening/night, coincident with the physiological peak of pineal melatonin excretion. Decreased melatonin levels have been reported in insomnia, which is an associated feature of RLS. Melatonin substitution improved insomnia. A potential association between the idiopathic RLS (iRLS) and alterations in melatonin excretion was therefore explored. Daytime (7:00–22:00 hr) and night‐time (22:00–7:00 hr) urinary excretion of 6‐OH‐melatonin‐sulfate (aMLTs) was measured in 15 patients with iRLS and 11 controls by a radioimmunoassay. There was no significant difference between daytime and night‐time urinary aMLTs excretion in iRLS as compared with controls (daytime: 6.14 ± 5.20 ng versus 5.02 ± 5.11 ng, NS; night‐time: 21.07 ± 17.05 ng versus 22.92 ± 16.52 ng, NS). Our data do not provide evidence for a decrease of cumulative melatonin production in iRLS. Insomnia in RLS does not seem to be correlated with a deficit of melatonin.
Melatonin: structural characterization of its non‐enzymatic mono‐oxygenate metabolite
Authors: Agozzino Pasquale , Avellone Giuseppe , Bongiorno David , Ceraulo Leopoldo , Filizzola Felice , Natoli Maria C. , Livrea Maria A. , Tesoriere Luisa
Published: October 2003

Abstract: Oxidation of melatonin by Fenton reagents as well as with hypochlorous acid or oxoferryl hemoglobin has been investigated. Analysis of products by low resolution/mass spectra (MS), high resolution/MS, 1H‐nuclear magnetic resonance (NMR), 13C‐NMR, correlated spectroscopy (COSY) and heterocorrelated spectroscopy (HETCOR) 2D NMR reveals the formation of a single mono‐oxygenated product under all conditions and unequivocally assigns the N‐[2‐(5‐methoxy‐2‐oxo‐2,3‐dihydro‐1H‐indol‐3‐yl)‐ethyl]‐acetamide structure, which had not been previously considered.
Synergistic Effect of Interleukin‐1α and Ceramide Analogue on Production of Prostaglandin E2 and F2α by Endometrial Stromal Cells
Authors: KAWANO YASUSHI , NAKAMURA SATOMI , FUKUDA JUNICHIRO , MIYAKAWA ISAO
Published: October 2003

PROBLEM: Prostaglandins (PGs) are synthesized in the endometrium. Our objective was to evaluate interleukin (IL)‐1α‐induced production of PGE2 and PGF2α in endometrial stromal cells (ESC) following treatment with ceramide analogues. 
METHODS OF STUDY: ESC were obtained from human uterine endometrium by enzymic digestion and filtration. ESC were treated with IL‐1α, IL‐1 receptor antagonist (ra), C2‐ceramide and C6‐ceramide. The concentrations of PGE2 and PGF2α in media were determined using ELISA. The induction of prostaglandin H synthase (PGHS)‐2 mRNA was also ascertained by reverse transcription‐polymerase chain reaction (RT‐PCR). 
RESULTS: The production of PGE2 and PGF2α was significantly increased by IL‐1α and suppressed by IL‐1 ra, in a dose‐dependent manner. PGF2α production was further increased by treatment with the combination of IL‐1α and C2‐ceramide as compared with IL‐1α treatment alone. There was no significant difference in PGE2 production between cells treated with IL‐1α and C2‐ceramide and those treated with IL‐1α alone. Both PGE2 and PGF2α production were significantly increased by treatment with IL‐1α and C6‐ceramide as compared with IL‐1α treatment alone. Treatment of ESC with IL‐1α stimulated PGHS‐2 mRNA. PGHS‐2 mRNA was decreased when IL‐1 ra was added to the IL‐1α‐stimulated cells. 
CONCLUSIONS: These results suggest that IL‐1α stimulates the production of PGE2 and PGF2α by a mechanism that involves the sphingomyelin‐ceramide system, and thus that ceramide may be important in increasing the production of PGE2 and PGF2α in the human endometrium.
Massive Intravenous Immunoglobulin Treatment in Women with Four or More Recurrent Spontaneous Abortions of Unexplained Etiology: Down‐Regulation of NK Cell Activity and Subsets
Authors: MORIKAWA MAMORU , YAMADA HIDETO , KATO EMI H. , SHIMADA SHIGEKI , KISHIDA TATSURO , YAMADA TAKAHIRO , FUJIMOTO SEIICHIRO , KOBASHI GEN
Published: October 2003

PROBLEM: The aims of this study were to investigate the efficacy of massive intravenous immunoglobulin (MIVIg) treatment for women with recurrent spontaneous abortion (RSA) of unexplained etiology, and to investigate changes in peripheral natural killer (NK) cell activity and subsets.  METHOD OF STUDY: MIVIg treatment was performed in 18 pregnancies from 15 women with 4 or more consecutive RSA of unexplained etiology. NK cell activity and subsets were assessed in 8 of the pregnancies.  RESULTS: 14 pregnancies resulted in live births and 4 resulted in abortions with chromosome abnormality. The pre‐infusion NK cell activity (mean±SD, 40.9±17.0%) at 4.4±0.5 weeks of gestation (GW) decreased to 15.0±7.9% at post‐infusion status (5.4±0.5 GW). Pre‐infusion percentages of CD56+CD16− cells (3.5±2.1%) and CD56+CD16− cells (16.8±8.8%) decreased to 3.0±2.2% and 11.1±6.9%, respectively, after MIVIg treatment.  CONCLUSIONS: MIVIg treatment was effective in all 14 pregnancies from RSA women of unexplained etiology, excluding 4 abortions with chromosome abnormality. Peripheral NK cell activity and subsets were suppressed by MIVIg treatment.
The Effects of Pregnancy on Myelin Basic Protein‐induced Experimental Autoimmune Encephalomyelitis in Lewis Rats: Suppression of Clinical Disease, Modulation of Cytokine Expression in the Spinal Cord Inflammatory Infiltrate and Suppression of Lymphocyte Proliferation by Pregnancy Sera
Authors: HARNESS J. , McCOMBE P.A.
Published: October 2003

PROBLEM: The present study was performed to explore the effects of pregnancy on experimental autoimmune encephalomyelitis (EAE) induced in Lewis rats by inoculation with myelin basic protein (MBP) (MBP‐EAE).  METHOD OF STUDY: MBP‐EAE was induced in pregnant and non‐pregnant rats and severity of disease evaluated. Serum from pregnant and non‐pregnant rats was used in standard lymphocyte proliferation assays. Real‐time polymerase chain reaction (PCR) was used to investigate the expression of cytokine mRNA in the inflammatory cells obtained from the spinal cord of rats on day 15 after inoculation.  RESULTS: Pregnant rats developed less severe disease than non‐pregnant rats. Serum from pregnant rats suppressed the proliferation of T lymphocytes in response to MBP. There was significantly increased expression of IL‐4, IL‐10 and TNF‐α mRNA in the spinal cord infiltrate of pregnant rats.  CONCLUSION: Circulating humoral factors and alteration in cytokine production by inflammatory cells may contribute to the suppression of EAE in pregnant rats.
Attentional shifts to smoking cues in smokers
Authors: Waters Andrew J. , Shiffman Saul , Bradley Brendan P. , Mogg Karin
Published: October 2003

Aims  Many theories of addiction assume that responses to drug cues maintain drug use and precipitate relapse. There is evidence that measures derived from experimental cognitive psychology yield important information about cue reactivity. We used a pictorial version of the visual probe task to evaluate: (i) whether minimally deprived smokers attend differentially to smoking cues (attentional bias); (ii) whether this bias is related to self‐reported craving and dependence; and (iii) whether it predicted outcome in a subsequent cessation attempt.

Design  Participants took part in a structured smoking cessation program. Each participant completed the visual probe task roughly 2 weeks before quitting while non‐deprived.

Setting  A research smoking cessation clinic.

Participants  141 heavy smokers seeking treatment for smoking cessation.

Measurements  The computerized attentional bias measure and self‐reported urge were taken in a laboratory session. Participants also monitored their smoking and craving on electronic diaries both when smoking ad libitum and for up to 6 weeks post‐cessation.

Findings  Participants were faster and more accurate in responding to a visual probe that replaced a smoking picture than to a neutral picture, indicating that they showed attentional bias towards the smoking cues. Attentional bias on the first half of the task correlated with pre‐task craving, indicating that the bias may tap motivational processes, but it did not predict outcome in smoking cessation.

Conclusions  The visual probe task can add useful information about attentional responses to drug cues. Further work is required to uncover the theoretical significance and utility of this measure.
Abuse and dependence potential for the non‐benzodiazepine hypnotics zolpidem and zopiclone: a review of case reports and epidemiological data
Authors: Hajak G. , Müller W. E. , Wittchen H. U. , Pittrow D. , Kirch W.
Published: October 2003

Aims  The non‐benzodiazepine hypnotics zolpidem and zopiclone, which are indicated for short‐term treatment of insomnia, were considered originally by physicians as almost devoid of abuse and dependence potential. Several recent publications, however, have suggested that both agents carry a significant risk of abuse. To substantiate and re‐evaluate this situation, the world literature was reviewed for cases of dependence of both agents; these cases were analysed in order to identify certain underlying patterns, if evident.

Methods  A systematic review based on a Medline literature search was conducted including the years 1966–2002 to assemble all available clinical case reports that were analysed for typical features of abuse and dependence according to prespecified criteria. Only case reports were of interest, and clinical studies were excluded. No limitations as to language or publication year were applied. The terms ‘zolpidem’, ‘zopiclone’ and ‘abuse’, ‘dependence’, ‘addiction’, ‘withdrawal’ and ‘intoxication’ were used to identify relevant publications. Potentially relevant citations were retrieved and assessed for inclusion independently by two authors.

Results  A total of 36 cases for zolpidem were identified, most of them reported in recent years, and 22 cases for zopiclone. Both sexes were involved to a similar extent; and cases were reported in all age groups. In extreme cases, dose increases reached a factor of 30–120 above the recommended doses. The majority of patients had a history of former drug or alcohol abuse and/or other psychiatric conditions.

Conclusion  On the basis of world‐wide prescription numbers, which are approximately twofold higher for zolpidem (1 338 774 000 tablets from June 2001 to June 2002 in Europe, Japan and United States) than for zopiclone (664 897 000 tablets during the same period in Europe and Japan), the relative incidence of reported dependence similar for both drugs and remarkably lower than that of benzodiazepines used for the treatment of disturbed sleep. The findings offer the conclusion that zolpidem and zopiclone are relatively safe drugs. However, as both drugs are psychotropic drugs, patients with a history of abuse or dependence and those with psychiatric diseases seem to be at increased risk of abuse of these agents.