bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of linear forms of the circular enterocin AS‐48 obtained by limited proteolysis
Authors: Montalbán-López Manuel , Spolaore Barbara , Pinato Odra , Martínez-Bueno Manuel , Valdivia Eva , Maqueda Mercedes , Fontana Angelo
Published: August 2008

AS‐48 is a 70‐residue circular peptide from Enterococcus faecalis with a broad antibacterial activity. Here, we produced by limited proteolysis a protein species carrying a single nicking and fragments of 55 and 38 residues. Nicked AS‐48 showed a lower helicity by far‐ultraviolet circular dichroism and a reduced stability to thermal denaturation, but it was active against the sensitive bacteria assayed. The fragments also partly retained the biological activity of the intact protein. These results indicate that circularization is not required for the bactericidal activity, but it is important to stabilize the native structure. Moreover, it is possible to reduce the sequence to a minimal AS‐48 domain without causing inactivation of this bacteriocin.
Behavioral therapy for urinary incontinence in India
Authors: Kumari Santosh , Jain Vanita , Mandal Arup Kumar , Singh Amarjeet
Published: August 2008

Objective

To ascertain the prevalence of urinary incontinence in a sample of women from northern India, and the impact of behavioral therapy to treat its occurrence and severity.

Methods

A randomized controlled trial conducted from 2005–2006 to test the null hypothesis that behavioral therapy would not have an effect on urinary incontinence. Following a prevalence study, a total of 198 women with urinary incontinence were randomized into 2 groups: an intervention group (behavioral therapy) and a control group (no therapy).

Results

The prevalence of urinary incontinence was 11.6%. After an 8‐month follow‐up period, 41 women (52.5%) in the intervention group had become continent, and severity had shifted from severe to mild in 19 women (24.4%). In contrast, 11 women (12.8%) in the control group had become continent. In the intervention group, mean daytime voiding frequency decreased from 9.56 to 7.64, mean nighttime voiding frequency decreased from 1.45 to 0.69, and mean episodes of urine leakage decreased from 1.97 to 0.23.

Conclusion

Behavioral therapy was effective in treating urinary incontinence, particularly in women with mild and moderate incontinence.
Democracy and the Logic of Political Survival
Authors: CLARKE KEVIN A. , STONE RANDALL W.
Published: August 2008

Although democracy is a key concept in political science, debate continues over definitions and mechanisms. Bueno de Mesquita, Smith, Siverson, & Morrow (2003) make the important claim that most of democracy's effects are in fact due to something conceptually simpler and empirically easier to measure than democracy: the size of the minimum winning coalition that selects the leader. The argument is intuitively appealing and supported by extensive data analysis. Unfortunately, the statistical technique they use induces omitted variable bias into their results. They argue that they need to control for democracy, but their estimation procedure is equivalent to omitting democracy from their analysis. When we reestimate their regressions controlling for democracy, most of their important findings do not survive.
Relationship between reproductive initiation and ear emergence development in Lolium perenne L.
Authors: HURLEY G. , GILLILAND T. J. , O'DONOVAN M.
Published: August 2008

During spring, perennial ryegrass tillers change from vegetative to reproductive growth in response to photoperiod and undergo irreversible morphological changes. The effect of latitude and meteorological factors on the timing of reproductive initiation and ear emergence (EE) were measured in the field on 40 vernalized spaced plants for each of eight cultivars. The measurements were made at two latitudes in Ireland (Moorepark 52°N, Crossnacreevy 54°N). There was a significant effect of site and cultivar on all the variables measured. Cultivar initiation responded to a specific photoperiod but detection through apical development incurred a small variation due to growing conditions affecting the time taken for a visible change in apical morphology to occur. When converted from photoperiod to initiation date this variance was minimal (±6 min). Timing of EE was dependent on growing conditions not photoperiod and so was specific to the studied conditions. As cultivar rank order for EE date was largely retained, there was a very strong correlation with published UK Plant Breeders Rights (PBR) heading dates for these cultivars, which in turn had a strong relationship with the ear initiation (EI) dates (R2=0·95). The latter relationship was sufficiently robust to allow estimation of photoperiod for any cultivar on the EU Common Catalogue based on its published heading date from Crossnacreevy, where the UK PBR trials are conducted. As photoperiod can be converted to calendar date by reference to latitude, this relationship can also be used to estimate the EI date for sites at latitudes other than those in the current study.
Trypanosomes in a declining species of threatened Australian marsupial, the brush-tailed bettongBettongia penicillata(Marsupialia: Potoroidae)
Authors: SMITH A. , CLARK P. , AVERIS S. , LYMBERY A. J. , WAYNE A. F. , MORRIS K. D. , THOMPSON R. C. A.
Published: August 2008

The brush-tailed bettong (Bettongia penicillata), or woylie, is a medium-sized macropod marsupial that has undergone a rapid and substantial decline throughout its home range in the Upper Warren region of Western Australia over a period of approximately 5 years. As part of an investigation into possible causes of the decline a morphologically distinctTrypanosomasp. was discovered by light microscopy in the declining population but was absent in a stable population within the Karakamia Wildlife Sanctuary. Further investigations employing molecular methods targeting variations in the 18s rRNA gene determined that the trypanosome was novel and was also present within the Karakamia population albeit at a much lower overall prevalence and individual parasitaemia levels. Phylogenetic analysis suggests the novelTrypanosomasp. to be closely related to other trypanosomes isolated from native Australian wildlife species. Although it appears unlikely that the parasite is solely responsible for the decline in woylie population size, it may (singularly or in conjunction with other infectious agents) predispose woylies to increased mortality.
Phylogenetic analysis of Trypanosoma vivax supports the separation of South American/West African from East African isolates and a new T. vivax-like genotype infecting a nyala antelope from Mozambique
Authors: RODRIGUES A. C. , NEVES L. , GARCIA H. A. , VIOLA L. B. , MARCILI A. , DA SILVA F. MAIA , SIGAUQUE I. , BATISTA J. S. , PAIVA F. , TEIXEIRA M. M. G.
Published: August 2008

In this study, we addressed the phylogenetic and taxonomic relationships of Trypanosoma vivax and related trypanosomes nested in the subgenus Duttonella through combined morphological and phylogeographical analyses. We previously demonstrated that the clade T. vivax harbours a homogeneous clade comprising West African/South American isolates and the heterogeneous East African isolates. Herein we characterized a trypanosome isolated from a nyala antelope (Tragelaphus angasi) wild-caught in Mozambique (East Africa) and diagnosed as T. vivax-like based on biological, morphological and molecular data. Phylogenetic relationships, phylogeographical patterns and estimates of genetic divergence were based on SSU and ITS rDNA sequences of T. vivax from Brazil and Venezuela (South America), Nigeria (West Africa), and from T. vivax-like trypanosomes from Mozambique, Kenya and Tanzania (East Africa). Despite being well-supported within the T. vivax clade, the nyala trypanosome was highly divergent from all other T. vivax and T. vivax-like trypanosomes, even those from East Africa. Considering its host origin, morphological features, behaviour in experimentally infected goats, phylogenetic placement, and genetic divergence this isolate represents a new genotype of trypanosome closely phylogenetically related to T. vivax. This study corroborated the high complexity and the existence of distinct genotypes yet undescribed within the subgenus Duttonella.
Synchronization of host-parasite cycles by means of diapause: host influence and parasite response to involuntary host shifting
Authors: CALERO-TORRALBO M. A. , VALERA F.
Published: August 2008

Many parasites require synchronization of their infective phases with the appearance of susceptible host individuals and, for many species, diapause is one of the mechanisms contributing to such coincidence. A variety of ecological factors, like changes in host temperature produced by involuntary host shifting (substitution of the usual host by an infrequent one), can modify host-parasite synchronization of diapausing ectoparasites of endothermic species. To understand the influence of host shifting on the mechanisms of parasite synchronization, we conducted experiments using the system formed by the ectoparasitic flyCarnus hemapterusand its avian hosts. We simulated the occurrence of the usual host and natural cases of host shifting by exposing overwintering carnid pupae from Bee-eater nests (Merops apiaster) to the earlier incubation periods of twoCarnushost species that frequently reoccupy Bee-eater nests. Pupae exposed to host shifting treatments advanced the mean date of emergence and produced an earlier and faster rate of emergence in comparison with pupae exposed both to the control (absence of any host) and Bee-eater treatments. The effect was more evident for the treatment resembling the host with the most dissimilar phenology to the one of the usual host. Our results show that host temperature is an environmental cue used by this nest-dwelling haematophagous ectoparasite and reveal thatCarnus hemapterushas some potential to react to involuntary host shifting by means of plasticity in the termination of diapause.
Anti-VSG antibodies induce an increase inTrypanosoma evansiintracellular Ca2+concentration
Authors: MENDOZA M. , UZCANGA G. L. , PACHECO R. , ROJAS H. , CARRASQUEL L. M. , GARCÍA-MARCHAN Y. , SERRANO-MARTÍN X. , BENAÍM G. , BUBIS J. , MIJARES A.
Published: August 2008

Trypanosoma evansiandTrypanosoma vivaxhave shown a very high immunological cross-reactivity. Anti-T. vivaxantibodies were used to monitor changes in theT. evansiintracellular Ca2+concentration ([Ca2+]i) by fluorometric ratio imaging from single parasites. A short-time exposure ofT. evansiparasites to sera fromT. vivax-infected bovines induced an increase in [Ca2+]i, which generated their complete lysis. The parasite [Ca2+]iboost was reduced but not eliminated in the absence of extracellular Ca2+or following serum decomplementation. Decomplemented anti-T. evansiVSG antibodies also produced an increase in the parasite [Ca2+]i, in the presence of extracellular Ca2+. Furthermore, this Ca2+signal was reduced following blockage with Ni2+or in the absence of extracellular Ca2+, suggesting that this response was a combination of an influx of Ca2+throughout membrane channels and a release of this ion from intracellular stores. The observed Ca2+signal was specific since (i) it was completely eliminated following pre-incubation of the anti-VSG antibodies with the purified soluble VSG, and (ii) affinity-purified anti-VSG antibodies also generated an increase in [Ca2+]iby measurements on single cells or parasite populations. We also showed that an increase of theT. evansi[Ca2+]iby the calcium A-23187 ionophore led to VSG release from the parasite surface. In addition,in vivoimmunofluorescence labelling revealed that anti-VSG antibodies induced the formation of raft patches of VSG on the parasite surface. This is the first study to identify a ligand that is coupled to calcium flux in salivarian trypanosomes.
Monoamine oxidase A and childhood adversity as risk factors for conduct disorder in females
Authors: Prom-Wormley E. C. , Eaves L. J. , Foley D. L. , Gardner C. O. , Archer K. J. , Wormley B. K. , Maes H. H. , Riley B. P. , Silberg J. L.
Published: August 2008

Background

Recent studies among males have reported a genotype–environment interaction (G×E) in which low-activity alleles at the monoamine oxidase A (MAOA) locus conferred greater sensitivity to the effects of childhood adversity on risk for conduct disorder (CD). So far, few studies of females have controlled for gene–environment correlation or used females heterozygous for this X-linked gene.

Method

Logistic regression analysis of a sample of 721 females ages 8–17 years from the longitudinal Virginia Twin Study of Adolescent Behavioral Development (VTSABD) assessed the additive effects ofMAOAgenotypes on risk for CD, together with the main effect of childhood adversity and parental antisocial personality disorder (ASP), as well as the interaction ofMAOAwith childhood adversity on risk for CD.

Results

A significant main effect of genotype on risk for CD was detected, where low-activityMAOAimparted the greatest risk to CD in girls while controlling for the significant effects of maternal ASP and childhood adversity. Significant G×E with weak effect was detected when environmental exposure was untransformed, indicating a higher sensitivity to childhood adversity in the presence of the high-activityMAOAallele. The interaction was no longer statistically significant after applying a ridit transformation to reflect the sample sizes exposed at each level of childhood adversity.

Conclusions

The main effect ofMAOAon risk for CD in females, its absence in males and directional difference of interaction is suggestive of genotype–sex interaction. As the effect of G×E on risk for CD was weak, its inclusion is not justified.
An investigation of temperament endophenotype candidates for early emergence of the core cognitive component of eating disorders
Authors: Wilksch S. M. , Wade T. D.
Published: August 2008

Background

This study was designed to investigate potential temperament endophenotypes for clinically significant importance of shape and weight.

Method

Seven temperament risk factors for eating disorders and the Eating Disorder Examination were assessed in 699 female twins aged 12–15 years. Each variable was evaluated against the following endophenotype criteria: associated with illness in the general population; found in non-affected family members at a higher rate than in the general population; and, heritable.

Results

All seven variables were significantly associated with clinically significant importance of shape and weight, while thin-ideal internalization, ineffectiveness, body dissatisfaction and sensitivity to punishment were found at significantly elevated levels in non-affected twins, when controlling for sister's temperament score. These four variables had genetic correlations with importance of shape and weight, ranging from 0.48 to 0.95.

Conclusions

Future research should evaluate the stability of the identified endophenotypes and their utility for predicting significant growth in importance of shape and weight, and also whether different endophenotypes emerge when the importance of weight and shape reaches its peak in adolescents, around 15 to 16 years of age.
Conservation on community lands: the importance of equitable revenue sharing
Authors: GROOM ROSEMARY , HARRIS STEPHEN
Published: August 2008

Attempts to establish local support for wildlife and conservation through the sharing of revenues and empowerment of local communities to manage their wildlife have proliferated over the past two decades. Data from two neighbouring Maasai group ranches in the wildlife dispersal area of Amboseli and Tsavo National Parks (Kenya) indicated one ranch generated considerable wildlife revenues from a tourist operation and community trust while the other received no direct benefits from wildlife. The overall attitude to wildlife on the ranch with wildlife revenues was significantly more positive, but attitudes within the ranch varied significantly, depending on both costs from wildlife and perception of the distribution of wildlife revenues. Ordinal logistic regression analyses showed that it was not the amount of revenue received or the scale of costs from wildlife which determined people's attitudes, but simply the presence or absence of wildlife benefits. The importance of addressing inequitable distribution of benefits is emphasized.
RESTRICTION OF FOURIER TRANSFORMS TO CURVES II: SOME CLASSES WITH VANISHING TORSION
Authors: BAK JONG-GUK , OBERLIN DANIEL M. , SEEGER ANDREAS
Published: August 2008

We consider the Fourier restriction operators associated to certain degenerate curves in ℝd for which the highest torsion vanishes. We prove estimates with respect to affine arclength and with respect to the Euclidean arclength measure on the curve. The estimates have certain uniform features, and the affine arclength results cover families of flat curves.
Dyadic coping and the significance of this concept for prevention and therapy
Authors: Bodenmann Guy
Published: August 2008

Abstract. This brief article aims to summarize the conceptual and clinical work done within the concept of dyadic coping by Bodenmann and colleagues at the Institute for Family Research and Counseling of the University of Fribourg (Switzerland). Apart from a new theoretical framework of dyadic coping, this group contributed to a better understanding of the role of dyadic coping for relationship functioning and well-being of the partners in many empirical studies. Based on these findings Bodenmann developed the Couples Coping Enhancement Traininig (CCET) that focuses on the enhancement of dyadic skills (among with dyadic coping play a crucial role). This program has been evaluated in several studies (randomized controlled trials and studies with matched samples) proving its efficacy.
The wide scope of medical psychology and sociology
Authors: Glaesmer Heide , Hinz Andreas , Brähler Elmar
Published: August 2008

Abstract. The Department of Medical Psychology and Sociology at the University of Leipzig deals with a wide scope of scientific working fields. First of all, the conduction of representative surveys for the validation of psychometric instruments, the exploration of multiple research topics and the supply of reliable information about public opinion is a central part of our work. These surveys basically contribute to an empirical foundation of the following research fields of our department: (1) epidemiologic research on mental disorders and bodily complaints, (2) development and validation of psychometric instruments, (3) health status and life conditions of care giving relatives, and (4) migration and health.
Health psychology and health promotion
Authors: Faltermaier Toni
Published: August 2008

Abstract. The Flensburg health psychology group takes a salutogenic perspective and aims at developing innovative health promotion approaches. It stands in the interdisciplinary context of health and educational sciences. Our focus in research is on both, stress processes and lay representations of health and illness in the context of salutogenic theories of health. Basic and applied research activities aim at developing subject-oriented approaches of prevention and health promotion that are designed to promote health resources and competencies in selected settings and target groups. Current research is concentrated on socially disadvantaged groups, on occupational groups and on men to develop tailored health promotion approaches that reach groups in need and which show sustainable effects.
Psychology of rehabilitation as a part of health psychology at the Division of Psychology of Rehabilitation at the University of Applied Sciences of Magdeburg and Stendal
Authors: Franke Gabriele Helga , Salewski Christel , Morfeld Matthias
Published: August 2008

Abstract. This article summarizes the current research activities at the Division of Psychology of Rehabilitation at the University of Applied Sciences Magdeburg-Stendal. Our research activities predominately focuses on chronic illness and disability encompassing a broad range of target populations such as adolescents with atopic excema, patients suffering from non-life-threatening diseases such as eye diseases to patients suffering from severe diseases such as HIV/AIDS or renal disease. From a theoretical perspective, our group aims at a better understanding of illness representations of patients as well as from non-patients. From a methodological perspective, our group aims at developing psychometric measures to assess health- and illness-related cognitions.
Social exchange processes, health behaviour, and health behaviour change
Authors: Scholz Urte , Hornung Rainer
Published: August 2008

Abstract. The main research areas of the Social and Health Psychology group at the Department of Psychology at the University of Zurich, Switzerland, are introduced. Exemplarily, three currently ongoing projects are described. The project ”Dyadic exchange processes in couples facing dementia” examines social exchanges in couples with the husband suffering from dementia and is based on Equity Theory. This project applies a multi-method approach by combining self-report with observational data. The ”Swiss Tobacco Monitoring System” (TMS) is a representative survey on smoking behaviour in Switzerland. Besides its survey character, the Swiss TMS also allows for testing psychological research questions on smoking with a representative sample. The project, ”Theory-based planning interventions for changing nutrition behaviour in overweight individuals”, elaborates on the concept of planning. More specifically, it is tested whether there is a critical amount of repetitions of a planning intervention (e.g., three or nine times) in order to ensure long-term effects.
Stress prevention and stress management in childhood and adolescence
Authors: Lohaus Arnold
Published: August 2008

Abstract. This paper provides an overview about research activities related to stress in children and adolescents at the University of Bielefeld. In this context, two stress prevention programs related to (a) elementary school children and (b) adolescents of grades 8 and 9 were developed and evaluated. The program evaluations compared different program versions and showed favourable results for problem solving, while program versions focusing on relaxation training were less effective. This was the reason to evaluate the effects of relaxation training in children and adolescents more systematically. Different relaxation techniques were compared with providing non-tension producing stories to children and adolescents. The results showed clear short-term effects of relaxation training, although this effect was also produced by non-tension producing stories. The use of additional e-learning units is addressed in the final parts of the paper as a way of increasing the motivation of adolescents to participate in stress prevention training.
Symptomspezifische Subgruppen der Panikstörung
Authors: Andor Fabian , Glöckner-Rist Angelika , Gerlach Alexander L. , Rist Fred
Published: August 2008

Zusammenfassung. Theoretischer Hintergrund: In Modellen der Panikstörung wird eine erhöhte Sensitivität für körperliche Vorgänge angenommen. Die Spezifität dieser Sensitivität für verschiedene körperliche Funktionsbereiche ist unklar. Dies soll anhand der berichteten Symptome eines Panikanfalls geprüft werden. Methode: Die Angaben von 498 Panikpatienten zu 10 körperlichen Symptomen während eines typischen Panikanfalls (DSM-III-R) wurden Latent Class und Latent Class Faktorenanalysen unterzogen. Ergebnisse: Vier etwa gleichgroße Subgruppen von Panikpatienten mit unterschiedlichen Ausprägungen auf zwei binären Symptomfaktoren wurden identifiziert. Eine Gruppe hatte überwiegend respiratorische Symptome, eine weitere überwiegend vestibuläre Symptome. In den beiden übrigen Gruppen waren alle Symptome gleichermaßen stark bzw. schwach ausgeprägt. Schlussfolgerungen: Zwei der identifizierten Subgruppen scheinen spezifisch sensitiv für respiratorische bzw. vestibuläre Körpervorgänge zu sein. Für die verhaltenstherapeutische Panikbehandlung verweist dieser Befund darauf, spezifische Expositionsübungen zur Steigerung der Erfolgsquoten einzusetzen.
Morningness-Eveningness Among German and Spanish Adolescents 12–18 Years
Authors: Díaz-Morales Juan Francisco , Randler Christoph
Published: August 2008

Individual differences in human biological rhythms and diurnal preference (morningness-eveningness) are often based on self-report scales. Here, we compare Spanish (N = 771) and German (N = 1,182) adolescents (12–18 years) using the Composite Scale of Morningness (CSM). A 3-factorial solution of the CSM was supported in both countries, morningness, activity planning, and alertness factors, and the last two factors were invariant across countries. Morningness decreased with age, and higher morningness was found in German pupils. Gender differences were not significant concerning the alertness factor but existed in the activity-planning factor with girls scoring higher, and in the morningness factor with boys scoring higher. Interactions suggest that the linear trend toward eveningness is less pronounced in Spanish adolescents, whereas German boys showed the steepest linear decline in their over time compared to German girls and to Spanish boys who showed a U-shaped tendency.
Modeling Human Dynamics by Means of Cointegration Methodology
Authors: Stroe-Kunold Esther , Werner Joachim
Published: August 2008

The cointegration approach, developed by Engle and Granger (1987 ), allows treating nonstationary (i.e., integrated) time series as a multivariate system if their linear combination is stationary. Various psychological processes are often integrated but interconnected. Thus, cointegration methodology offers flexible techniques for modeling human dynamics. This paper introduces cointegration methodology to psychological researchers. After a brief introduction to time-series analysis, we summarize cointegration techniques and describe the so-called cointegration vector (β) and adjustment coefficient (α), the main parameters of cointegrated systems. We show that β and α are flexible tools for modeling long-term equilibrium as well as short-term dynamic adjustment within the multivariate system. An empirical example demonstrates advantages of cointegration methods in a typical research situation. Possible domains of application within the scope of psychology are discussed.
Fault gouge evolution and its dependence on normal stress and rock strength—Results of discrete element simulations: Gouge zone micromechanics
Authors: Guo Yonggui , Morgan Julia K.
Published: August 2008

We simulate the breakdown of fault blocks using the Distinct Element Method (DEM) in two dimensions in order to study the frictional strength, mechanical behavior, and stress and strain state of evolving fault gouge and their dependence on normal stress σn and uniaxial compressive strength σucs. The fault blocks were generated by adding breakable elastic bonds between adjacent circular particles to obtain a given σucs in a range from 100 to 260 MPa and deformed in a direct shear configuration over a range of σn from 10 to 100 MPa. The simulated shear zones experienced two growth stages: fast and slow. During the fast growth stage, the shear zones attain a peak friction value within the first 2% shear strain, which is enhanced in low‐σn and high‐σucs experiments. The residual sliding friction decreases nonlinearly with increasing ratio of σn/σucs. The variation in friction is related to volume strain and localized deformation, both of which are dependent on strain, σn, σucs, and associated variations in gouge properties. The complex correlations reflect the complexity and diversity of micromechanical processes in response to changing physical and structural properties of fault gouge as it evolves, with implications for fault behavior through time and space.
Model calculation of production rates, ion and electron densities in the evening troposphere of Mars at latitudes 67°N and 62°S: Seasonal variability
Authors: Haider S. A. , Sheel Varun , Singh V. , Maguire W. C. , Molina‐Cuberos G. J.
Published: August 2008

We have developed a model to calculate the production rates and densities of positive and negative ions in the troposphere of Mars at evening. Using this model, the densities of 35 ions (Ar+, O2+, CO2+, O2+CO2, NO+, H3O+, H3O+H2O, H3O+(H2O)2, H3O+(H2O)3, H3O+(H2O)4, H3O+HO, CO2+CO2, CO+, C+, N2+, NO+CO2, N+, O2+(CO2)2, O2+H2O, O2+(H2O)2, O4+, O+, CO3−H2O, CO3−(H2O)2, CO3−, CO4−, NO2−, NO2−H2O, NO2−(H2O)2, NO3−, NO3−H2O, NO3−(H2O)2, O2−, O3−, O−) are estimated in summer and winter at latitudes 67°N and 62°S for solar zenith angles 80° and 85°, respectively. The impact ionization source is taken as galactic cosmic rays. The model atmospheres at these locations are constructed from air density measured by radio occultation experiment aboard Mars Global Surveyor. The maximum electron densities in southern winter and northern summer are obtained at altitudes ∼25 km and ∼30 km, respectively, due to high efficiency of electron attachment to Ox molecules. Of the 35 ions considered in the model, the chemistry of 9 major ions (H3O+(H2O)n for n = 1, 2, 3, 4 and CO4−, CO3−, NO2−H2O and CO3−(H2O)n for n = 1, 2) are discussed in this paper. The ion densities are changed by factors of 5 to 10 between these two seasons.
A promising location in Patagonia for paleoclimate and paleoenvironmental reconstructions revealed by a shallow firn core from Monte San Valentín (Northern Patagonia Icefield, Chile)
Authors: Vimeux Françoise , de Angelis Martine , Ginot Patrick , Magand Olivier , Casassa Gino , Pouyaud Bernard , Falourd Sonia , Johnsen Sigfus
Published: August 2008

The study of past climate variability from ice core investigations has been largely developed both in polar areas over the past decades and, more recently, in tropical regions, specifically along the South American Andes between 0° and 20°S. However a large gap still remains at mid‐latitudes in the Southern Hemisphere. In this framework, a 15.3‐m long shallow firn core has been extracted in March 2005 from the summit plateau of Monte San Valentín (3747 m, 46°35′S, 73°19′W) in the Northern Patagonia Icefield to test its potential for paleoclimate and paleoenvironmental reconstructions. The firn temperature is −11.9°C at 10‐m depth allowing to expect well preserved both chemical and isotopic signals, unperturbed by water percolation. The dating of the core, on the basis of a multi‐proxy approach combining annual layer counting and radionuclide measurements, shows that past environment and climate can be reconstructed back to the mid‐1960s. A mean annual snow accumulation rate of 36 ± 3 cm year−1 (i.e., 19 ± 2 g cm−2 year−1) is inferred, with a snow density varying between 0.35 and 0.6 g cm−3, which is much lower than accumulation rates previously reported in Patagonia at lower elevations. Here, we present and discuss high‐resolution profiles of the isotopic composition of the snow and selected chemical markers. These data provide original information on environmental conditions prevailing over Southern Patagonia in terms of air masses trajectories and origins and biogeochemical reservoirs. Our main conclusion is that the San Valentín site is not only influenced by air masses originating from the southern Pacific and directly transported by the prevailing west winds but also by inputs from South American continental sources from the E–NE, sometimes mixed with circumpolar aged air masses, the relative influence of these two very distinct source areas changing at the interannual timescale. Thus this site should offer a wealth of information regarding (South) Pacific, Argentinian NE–E areas and Antarctic climate variability.
Interannual variability in trophic status of shallow lakes on the Boreal Plain: Is there a climate signal?
Authors: Sass G. Z. , Creed I. F. , Bayley S. E. , Devito K. J.
Published: August 2008

We explored relations between climate and trophic status of shallow lakes (lake area > 5 ha, mean depth < 3.2 m) located on the subhumid western Boreal Plain of Canada. Correlation and regression analyses were used to assess the association between indicators of climate and satellite‐based estimates of trophic status (chlorophyll a (Chl a)). Chl a was derived using red band reflectance of Landsat satellite images for 76 lakes, which were then averaged for each year to produce a landscape median for summer (August) over a 20‐year period from 1984 and 2003. Our results showed that climate was related to interannual changes in trophic status. Average May temperature was positively correlated to Chl a, suggesting the importance of conditions in the early part of the growing season. Growing season effective precipitation (P – PET) was negatively correlated to Chl a such that wetter conditions seemed to lead to a dilution of Chl a. Very wet years resulted in a larger Chl a drop than one expected by a linear model, suggesting greater water contribution from the landscape. P – PET explained 64% of the variance in Chl a using a nonlinear regression tree. Our study offers clues as to how shallow lake systems may behave on the subhumid Boreal Plain as a function of future climate change.
Strong internal tides in the Kara Gates Strait
Authors: Morozov Eugene G. , Paka Vadim T. , Bakhanov Victor V.
Published: August 2008

We analyze towed CTD measurements, numerical model calculations, and radar images in the Strait of Kara Gates. The measurements were made during an expedition in September 2007. Strong internal tides propagating from the Kara Strait to the Barents Sea were recorded. The internal waves are intensified by the opposite current from the Barents Sea. An internal bore followed by a packet of short‐period internal waves is found southwest of the strait. Radar images show that short‐period internal waves are generated after the internal bore. A hydraulic jump is found on the eastern side of the strait. Numerical modeling agrees with the experimental results.
A new methodology for cloud detection and classification with ASTER data
Authors: Hulley G. C. , Hook S. J.
Published: August 2008

High spatial resolution sensors such as Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) have the potential to produce gridded, large area datasets of surface parameters such as elevation and emissivity. These datasets are typically derived by combining all clear‐sky pixels over a given location for a specified time period necessitating the use of an automated cloud detection and classification algorithm. The current ASTER L1A cloud mask lacks several key features needed to use it for this purpose. We have developed a new cloud detection algorithm which addresses these limitations by using a 2‐pass approach similar to Landsat‐7 and including further spectral tests for cirrus and cloud shadows from MODIS. The new cloud detection methodology is described together with several case studies that highlight key aspects of the algorithm and comparisons with the MODIS and the current ASTER L1A cloud mask.
Bacteria associated with iron seeps in a sulfur-rich, neutral pH, freshwater ecosystem
Authors: Haaijer Suzanne C M , Harhangi Harry R , Meijerink Bas B , Strous Marc , Pol Arjan , Smolders Alfons J P , Verwegen Karin , Jetten Mike S M , Op den Camp Huub J M
Published: August 2008

The freshwater nature reserve De Bruuk is an iron- and sulfur-rich minerotrophic peatland containing many iron seeps and forms a suitable habitat for iron and sulfur cycle bacteria. Analysis of 16S rRNA gene-based clone libraries showed a striking correlation of the bacterial population of samples from this freshwater ecosystem with the processes of iron reduction (genus Geobacter), iron oxidation (genera Leptothrix and Gallionella) and sulfur oxidation (genus Sulfuricurvum). Results from fluorescence in situ hybridization analyses with a probe specific for the beta-1 subgroup of Proteobacteria, to which the genera Leptothrix and Gallionella belong, and newly developed probes specific for the genera Geobacter and Sulfuricurvum, supported the clone library data. Molecular data suggested members of the epsilonproteobacterial genus Sulfuricurvum as contributors to the oxidation of reduced sulfur compounds in the iron seeps of De Bruuk. In an evaluation of anaerobic dimethyl sulfide (DMS)-degrading activity of sediment, incubations with the electron acceptors sulfate, ferric iron and nitrate were performed. The fastest conversion of DMS was observed with nitrate. Further, a DMS-oxidizing, nitrate-reducing enrichment culture was established with sediment material from De Bruuk. This culture was dominated by dimorphic, prosthecate bacteria, and the 16S rRNA gene sequence obtained from this enrichment was closely affiliated with Hyphomicrobium facile, which indicates that the Hyphomicrobium species are capable of both aerobic and nitrate-driven DMS degradation.
Effect of Current and Midlife Obesity Status on Mortality Risk in the Elderly
Authors: Janssen Ian , Bacon Eric
Published: August 2008

The primary purpose of this study was to determine whether current and midlife obesity status provide independent information on mortality risk in elderly persons. Analyses were based on 3,238 participants from the original Framingham Heart Study (FHS) cohort who lived to at least 70 years of age and who had BMI measures from when they were in their 50s. Within this group of 70‐year olds, obesity based on current BMI was associated with a 21% increased risk of mortality (P = 0.019) whereas obesity in 70‐year olds based on BMI measures obtained at around 50 years of age was associated with a 55% increased risk of mortality (P < 0.0001). Compared to 70‐year olds who were nonobese at both 50 and 70 years of age, mortality risk was increased by 47% (P < 0.001) in those who were obese at both 50 and 70 years of age, increased by 56% (P < 0.001) in those who were obese at 50 years of age and nonobese at 70 years of age, and not significantly different (P > 0.9) in those who were nonobese at 50 years of age and obese at 70 years of age. In summary, in this cohort of elderly adults, midlife and current BMI had independent effects on mortality risk. Specifically, although mortality risk was increased in obese older adults who were already obese at midlife, this was not the case for newly obese older adults. Conversely, nonobese older adults who were obese at midlife had an increased mortality risk. These observations imply that it is imperative to consider an elderly adult's BMI in context of their BMI at midlife.
Accommodation of physostigmine and its analogues by acetylcholinesterase is dominated by hydrophobic interactions
Authors: Barak Dov , Ordentlich Arie , Stein Dana , Yu Qian-sheng , Greig Nigel H. , Shafferman Avigdor
Published: August 2008

The role of the functional architecture of the HuAChE (human acetylcholinesterase) in reactivity toward the carbamates pyridostigmine, rivastigmine and several analogues of physostigmine, that are currently used or considered for use as drugs for Alzheimer's disease, was analysed using over 20 mutants of residues that constitute the interaction subsites in the active centre. Both steps of the HuAChE carbamylation reaction, formation of the Michaelis complex as well as the nucleophilic process, are sensitive to accommodation of the ligand by the enzyme. For certain carbamate/HuAChE combinations, the mode of inhibition shifted from a covalent to a noncovalent type, according to the balance between dissociation and covalent reaction rates. Whereas the charged moieties of pyridostigmine and rivastigmine contribute significantly to the stability of the corresponding HuAChE complexes, no such effect was observed for physostigmine and its analogues, phenserine and cymserine. Moreover, physostigmine-like ligands carrying oxygen instead of nitrogen at position −1 of the tricyclic moiety (physovenine and tetrahydrofurobenzofuran analogues) displayed comparable structure–function characteristics toward the various HuAChE enzymes. The essential role of the HuAChE hydrophobic pocket, comprising mostly residues Trp86 and Tyr337, in accommodating (−)-physostigmine and in conferring ∼300-fold stereoselectivity toward physostigmines, was elucidated through examination of the reactivity of selected HuAChE mutations toward enantiomeric pairs of different physostigmine analogues. The present study demonstrates that certain charged and uncharged ligands, like analogues of physostigmine and physovenine, seem to be accommodated by the enzyme mostly through hydrophobic interactions.
Self-organization of multivalent counterions in polyelectrolyte brushes
Authors: Jiang Tao , Wu Jianzhong
Published: August 2008

We investigated the swelling behavior and density distributions of polyion segments and multivalent counterions in polyelectrolyte brushes within a primitive model that represents both polyion segments and salt ions as charged spheres and the solvent as a continuous dielectric medium. The numerical performance of a previously proposed nonlocal density functional theory (NLDFT) was tested with Monte Carlo simulations for multivalent systems and compared with the Poisson–Boltzmann equation that ignores the ionic size and electrostatic correlations. The NLDFT predicts that in the limit of low salt concentration, trivalent counterions can self-organize into a one-dimensional wavelike structure within the oppositely charged polyelectrolyte brush. Multivalent counterions introduce electrostatic correlations responsible for the nonmonotonic swelling of the brush which is qualitatively different from that in a monovalent solution. While in a monovalent solution the brush thickness increases monotonically with the grafting density, in a trivalent solution the swelling behavior resembles that for a neutral brush in a poor solvent. The NLDFT was also used to investigate the effects of ionic size on the brush swelling and counterion organization.
Gaussian-based techniques for quantum propagation from the time-dependent variational principle: Formulation in terms of trajectories of coupled classical and quantum variables
Authors: Shalashilin Dmitrii V. , Burghardt Irene
Published: August 2008

In this article, two coherent-state based methods of quantum propagation, namely, coupled coherent states (CCS) and Gaussian-based multiconfiguration time-dependent Hartree (G-MCTDH), are put on the same formal footing, using a derivation from a variational principle in Lagrangian form. By this approach, oscillations of the classical-like Gaussian parameters and oscillations of the quantum amplitudes are formally treated in an identical fashion. We also suggest a new approach denoted here as coupled coherent states trajectories (CCST), which completes the family of Gaussian-based methods. Using the same formalism for all related techniques allows their systematization and a straightforward comparison of their mathematical structure and cost.
A priori direct numerical simulation assessment of algebraic flame surface density models for turbulent premixed flames in the context of large eddy simulation
Authors: Chakraborty Nilanjan , Klein Markus
Published: August 2008

Flame surface density (FSD) based reaction rate closure is one of the most important approaches in turbulent premixed flame modeling. The algebraic models for FSD based on power laws often require information about the fractal dimension D and the inner cut-off scale ηi. In the present study, two three-dimensional direct numerical simulation (DNS) databases for freely propagating statistically planar turbulent premixed flames are analyzed among which the flame in one case belongs to the corrugated flamelet (CF) regime, whereas the other falls well within the thin reaction zone (TRZ) regime. It is found that D for the flame in the TRZ regime is greater than the value obtained for the flame in the CF regime. For the flame within the TRZ regime, the fractal dimension is found to be 7/3, which is the same as D for a material surface in a turbulent environment. For the flame in the CF regime, ηi is found to scale with the Gibson scale, whereas ηi is found to scale with the Kolmogorov length scale for the flame in the TRZ regime. Based on these observations a new algebraic model for FSD is proposed, where D and ηi are expressed as functions of Karlovitz number. The performances of the new and existing algebraic models for FSD are compared with the corresponding values obtained from DNS databases.
Principles of design of a set-reset finite state logic nanomachine
Authors: Klein Michael , Levine R. D. , Remacle F.
Published: August 2008

Pulsed electrical set and reset inputs are used to simulate the temporal action of a finite state machine in a three terminal configuration for a variety of arrangements. The gate electrode is necessary only if it is of interest to tune the tunneling rate and to compensate for background charges. When the output is the current, a source and drain electrodes are required. If the output is determined by measuring charge occupancy, then a single junction suffices. The electron transfer rates are computed from the free energy change for a single electron transfer to or from a quantum dot of size such that only charge quantization matters. For a small enough dot the device could operate at room temperature. An asymmetric configuration of the source and drain favors a longer term time preservation of the memory of the device. An alternative design that operates with the same energetics and kinetic parameters is to pulse the resistance rather than the voltage.
Self-consistent gain analysis of type-II ‘W’ InGaN–GaNAs quantum well lasers
Authors: Zhao Hongping , Arif Ronald A. , Tansu Nelson
Published: August 2008

Type-II InGaN–GaNAs quantum wells (QWs) with thin dilute-As (∼3%) GaNAs layer are analyzed self-consistently as improved III-nitride gain media for diode lasers. The band structure is calculated by using a six-band k⋅p formalism, taking into account valence band mixing, strain effect, spontaneous and piezoelectric polarizations, as well as the carrier screening effect. The type-II InGaN–GaNAs QW structure allows large electron-hole wave function overlap by confining the hole wave function in the GaNAs layer of the QW. The findings based on self-consistent analysis indicate that type-II InGaN-GaNAs QW active region results in superior performance for laser diodes, in comparison to that of conventional InGaN QW. Both the spontaneous emission radiative recombination rate and optical gain of type-II InGaN–GaNAs QW structure are significantly enhanced. Reduction in the threshold current density of InGaN–GaNAs QW lasers is also predicted.
Anisotropic photonic structures induced by three-dimensional vector holography in dye-doped liquid crystals
Authors: Sasaki Tomoyuki , Ono Hiroshi , Kawatsuki Nobuhiro
Published: August 2008

Periodic anisotropic structures were induced by means of a three-dimensional vector holographic technique in an azo-dye-doped liquid crystal composite with uniaxial alignment. The three-dimensional vector hologram was fabricated by both the polarization interference and the polarization propagation in the anisotropic recording medium. In order to obtain clear insight into the optical properties of three-dimensional vector holograms, various types of structures were induced by changing the polarization states and incident angles of the recording beams. The diffraction properties of various types of three-dimensional vector holograms were calculated by the finite-difference time-domain method, and the theoretical explanations were in good agreement with the experimental results.