bluuebunny/crossref_metadata_2025 huggingface dataset:
Damping and local control of mirror suspensions for laser interferometric gravitational wave detectors
Authors: Strain K. A. , Shapiro B. N.
Published: April 2012

The mirrors of laser interferometric gravitational wave detectors hang from multi-stage suspensions. These support the optics against gravity while isolating them from external vibration. Thermal noise must be kept small so mechanical loss must be minimized and the resulting structure has high-Q resonances rigid-body modes, typically in the frequency range between about 0.3 Hz and 20 Hz. Operation of the interferometer requires these resonances to be damped. Active damping provides the design flexibility required to achieve rapid settling with low noise. In practice there is a compromise between sensor performance, and hence cost and complexity, and sophistication of the control algorithm. We introduce a novel approach which combines the new technique of modal damping with methods developed from those applied in GEO 600. This approach is predicted to meet the goals for damping and for noise performance set by the Advanced LIGO project.
Note: Development of fast heating inert gas annealing apparatus operated at atmospheric pressure
Authors: Das S. C. , Majumdar A. , Shripathi T. , Hippler R.
Published: April 2012

Here, we report the development of a simple, small, fast heating, and portable, homemade, inert gas (Ar) atmospheric annealing setup. Instead of using a conventional heating element, a commercial soldering rod having an encapsulated fast heating heater is used here. The sample holder is made of a block of stainless steel. It takes 200 s to reach 700 °C, and 10 min to cool down. The probability of oxidation or surface contamination has been examined by means of x ray photoelectron spectroscopy of virgin Cu sample after annealing at 600 °C. In addition, we compare the annealing of a hydrogenated carbon nitride film (HCNx) in both a conventional vacuum and our newly developed ambient Ar atmosphere setup.
Localization effects in the tunnel barriers of phosphorus-doped silicon quantum dots
Authors: Ferrus T. , Rossi A. , Lin W. , Williams D. A. , Kodera T. , Oda S.
Published: April 2012

We have observed a negative differential conductance with singular gate and source-drain bias dependences in a phosphorus-doped silicon quantum dot. Its origin is discussed within the framework of weak localization. By measuring the current-voltage characteristics at different temperatures as well as simulating the tunneling rates dependences on energy, we demonstrate that the presence of shallow energy defects together with an enhancement of localization satisfactory explain our observations. Effects observed in magnetic fields are also discussed.
The inexorable resistance of inertia determines the initial regime of drop coalescence
Authors: Paulsen Joseph D. , Burton Justin C. , Nagel Sidney R. , Appathurai Santosh , Harris Michael T. , Basaran Osman A.
Published: April 2012

Drop coalescence is central to diverse processes involving dispersions of drops in industrial, engineering, and scientific realms. During coalescence, two drops first touch and then merge as the liquid neck connecting them grows from initially microscopic scales to a size comparable to the drop diameters. The curvature of the interface is infinite at the point where the drops first make contact, and the flows that ensue as the two drops coalesce are intimately coupled to this singularity in the dynamics. Conventionally, this process has been thought to have just two dynamical regimes: a viscous and an inertial regime with a cross-over region between them. We use experiments and simulations to reveal that a third regime, one that describes the initial dynamics of coalescence for all drop viscosities, has been missed. An argument based on force balance allows the construction of a new coalescence phase diagram.
Met expectations and the wellbeing of diaspora immigrants: A longitudinal study
Authors: Mähönen Tuuli Anna , Leinonen Elina , Jasinskaja‐Lahti Inga
Published: April 2012

Previous research has pointed to the importance of expectations for the adaptation of immigrants. However, most studies have been methodologically retrospective with only limited possibilities to show the optimal relationship between migrants’ expectations and actual acculturation experiences for their wellbeing and other aspects of psychological adaptation. Moreover, previous research has been conducted mostly among sojourners and students. This longitudinal study focused on the relationship between premigration expectations and postmigration experiences of diaspora immigrants from Russia to Finland (N = 153). We examined how the fulfillment of premigration expectations in social (i.e., family relations, friendships, and free time) and economic (i.e., occupational position, working conditions, and economic and career situation) domains affects immigrants’ wellbeing (i.e., satisfaction with life and general mood) after migration. Three alternative models of expectation confirmation (i.e., disconfirmation model, ideal point model, and the importance of experiences only) derived from previous organizational psychological research were tested with polynomial regression and response surface analysis. In the economic domain, immigrants’ expectations, experiences, and their interrelationship did not affect wellbeing in the postmigration stage. However, in the social domain, the more expectations were exceeded by actual experiences, the better were life satisfaction and the general mood of immigrants. The results underline the importance of social relationships and the context‐dependent nature of immigrants’ wellbeing. Interventions in the preacculturation stage should create positive but realistic expectations for diaspora immigrants and other groups of voluntary (re)migrants. Furthermore, policies concerning the postmigration stage should facilitate the fulfillment of these expectations and support the social adaptation of immigrants.
Attitudes toward War in the United States and Iran
Authors: Torabian Saba , Abalakina Marina
Published: April 2012

Understanding the determinants of attitudes toward war is important for the prevention of military conflicts and the promotion of peaceful conflict resolution. To examine American and Iranian attitudes toward war, questionnaires were administered to American and Iranian college students in the United States and Iran respectively. The results of the study revealed that American students generally have more positive attitudes toward war than Iranian students. Since most Iranians in the sample experienced eight years of war with Iraq whereas Americans never had direct experience of war, it was predicted that direct experiences of military action could explain this cross-national difference. Among Iranians those who experienced the Iran–Iraq war had more negative attitudes toward war compared to Iranians who did not have such experiences. The results further demonstrated that being authoritarian, religious and male were independently related to having positive attitudes toward war in both samples.
“The Permiak question”: Bolshevik central authorities, Russian and non-Russian provincial elites negotiating over autonomy in the early 1920s
Authors: Jääts Indrek
Published: April 2012

This is an article on Bolshevik nationalities policy and ethnic engineering, asking who, in fact, decided which populations belonged together as ethnic groups (narodnost') and thus had the right of national self-determination, and how the level of autonomy was determined for each ethnic unit. Scholars have dealt with Russian and Soviet nationalities issues for decades already, but they have turned their attention mainly to the larger nationalities (at the level of SSR, and to a lesser degree the levels of ASSR and autonomousoblast). I argue that the lower levels of national territorial autonomy in the Soviet Union (nationalokrug, raion, volost', andselsovet) are worthy of greater academic attention, at least from the ethnological point of view. Having this kind of low-level territorial autonomy has often been a question of to be or not to be for the small ethnic groups concerned, and hence the subject is connected with the question of preservation of cultural and linguistic diversity in Russia.
The Influence of Tag Presence on the Mortality of Juvenile Chinook Salmon Exposed to Simulated Hydroturbine Passage: Implications for Survival Estimates and Management of Hydroelectric Facilities
Authors: Carlson Thomas J. , Brown Richard S. , Stephenson John R. , Pflugrath Brett D. , Colotelo Alison H. , Gingerich Andrew J. , Benjamin Piper L. , Langeslay Mike J. , Ahmann Martin L. , Johnson Robert L. , Skalski John R. , Seaburg Adam G. , Townsend Richard L.
Published: April 2012

Each year, telemetry tags (acoustic, radio, and passive integrated transponder tags) are surgically implanted into thousands of fish to assess their passage and survival through hydropower facilities. One passage route that is of particular concern is through hydroturbines, where fish may be exposed to a range of potential injuries that include barotraumas from rapid decompression. The change in pressure from acclimation to exposure (nadir) has been identified as an important factor in predicting the likelihood of mortality and injury for juvenile Chinook salmon Oncorhynchus tshawytscha undergoing rapid decompression associated with simulated turbine passage. The presence of telemetry tags has also been shown to influence the likelihood of mortality and injury for juvenile Chinook salmon. We investigated the likelihood of mortality and injury for telemetry-tagged juvenile Chinook salmon that were exposed to a range of pressure changes associated with simulated turbine passage. Several factors were examined as predictors of mortal injury for fish undergoing rapid decompression; of these factors, the loge transformed ratio of acclimation pressure: exposure pressure (LRP) and the tag burden (tag mass expressed as a percentage of fish mass) were the most predictive. As the LRP and tag burden increased, the likelihood of mortal injury also increased. Our results suggest that previous estimates of survival for juvenile Chinook salmon passing through hydroturbines were negatively biased due to the presence of telemetry tags, and this has direct implications for the management of hydroelectric facilities. Realistic examples indicate how the bias in turbine passage survival estimates could be 20% or higher depending on the LRP and tag burden. Negative bias would increase as the tag burden and the pressure change ratio increase and therefore has direct implications for survival estimates. We recommend that future hydroturbine survival studies use the smallest telemetry tags possible to minimize the potential bias associated with tag presence.

Received January 9, 2011; accepted October 11, 2011
Use of a Seismic Air Gun to Reduce Survival of Nonnative Lake Trout Embryos: A Tool for Conservation?
Authors: Cox Benjamin S. , Dux Andrew M. , Quist Michael C. , Guy Christopher S.
Published: April 2012

The detrimental impacts of nonnative lake trout Salvelinus namaycush in the western USA have prompted natural resource management agencies in several states to implement lake trout suppression programs. Currently, these programs rely on mechanical removal methods (i.e., gill nets, trap nets, and angling) to capture subadult and adult lake trout. We conducted a study to explore the potential for using high-intensity sound from a relatively small (655.5 cm3 [40 in3]) seismic air gun to reduce survival of lake trout embryos. Lake trout embryos at multiple stages of development were exposed to a single discharge of the seismic air gun at two depths (5 and 15 m) and at two distances from the air gun (0.1 and 2.7 m). Control groups for each developmental stage, distance, and depth were treated identically except that the air gun was not discharged. Mortality in lake trout embryos treated at 0.1 m from the air gun was 100% at 74 daily temperature units in degrees Celsius (TU°C) at both depths. Median mortality in lake trout embryos treated at 0.1 m from the air gun at 207 TU°C (93%) and 267 TU°C (78%) appeared to be higher than that of controls (49% and 48%, respectively) at 15-m depth. Among the four lake trout developmental stages, exposure to the air gun at 0.1 m resulted in acute mortality up to 60% greater than that of controls. Mortality at a distance of 2.7 m did not appear to differ from that of controls at any developmental stage or at either depth. Our results indicate that seismic air guns have potential as an alternative tool for controlling nonnative lake trout, but further investigation is warranted.

Received September 13, 2011; accepted January 3, 2012
Strong green emission in ZnO films after H2 surface treatment
Authors: Li T , Herng T S , Liang H K , Bao N N , Chen T P , Wong J I , Xue J M , Ding J
Published: April 2012

Using a two-step fabrication technique (pulsed laser deposition (PLD) and H2 surface treatment), we fabricated ZnO thin films that could emit ultra-strong green emission with coexistence of random lasing phenomenon. After PLD deposition, the as-prepared undoped ZnO thin films (200–500 nm) were annealed in Ar 95%–H25% ambient at 500 °C. The H2 treatment led to the formation of a porous structure that creates substantial optical cavities (diameter ∼1.3 µm). Surprisingly, these optical cavities tremendously amplified the green emission rather than ultraviolet (UV) emission. There was insignificant change in emission intensity after high-temperature annealing (700 °C) in O2 and acetone dipping, indicating the samples are thermally and chemically stable. The samples exhibited a high quantum yield of 32%. We studied the origin of this ultra-strong green emission using low-temperature photoluminescence, extensive structural study and cyclic annealing. The results suggested that neither hydrogen nor VO plays a role in green emission. The green emission was attributed mainly to the complex defects and the presence of structural defects in the porous structure. In addition, we demonstrated the feasibility of large-scale green emission ZnO fabrication via micro-size patterning, paving a way to practical optoelectronic applications.
Fast, kinetically self-consistent simulation of RF modulated plasma boundary sheaths
Authors: Shihab Mohammed , Ziegler Dennis , Brinkmann Ralf Peter
Published: April 2012

A mathematical model is presented which enables the efficient, kinetically self-consistent simulation of RF modulated plasma boundary sheaths in all technically relevant discharge regimes. It is defined on a one-dimensional geometry where a Cartesian x-axis points from the electrode or wall at x
E ≡ 0 towards the plasma bulk. An arbitrary endpoint x
B is chosen ‘deep in the bulk’. The model consists of a set of kinetic equations for the ions, Boltzmann's relation for the electrons and Poisson's equation for the electrical field. Boundary conditions specify the ion flux at x
B and a periodically—not necessarily harmonically—modulated sheath voltage V(t) or sheath charge Q(t). The equations are solved in a statistical sense. However, it is not the well-known particle-in-cell (PIC) scheme that is employed, but an alternative iterative algorithm termed ensemble-in-spacetime (EST). The basis of the scheme is a discretization of the spacetime, the product of the domain [x
E, x
B] and the RF period [0, T]. Three modules are called in a sequence. A Monte Carlo module calculates the trajectories of a large set of ions from their start at x
B until they reach the electrode at x
E, utilizing the potential values on the nodes of the spatio-temporal grid. A harmonic analysis module reconstructs the Fourier modes n
im
(x) of the ion density n
i(x, t) from the calculated trajectories. A field module finally solves the Boltzmann–Poisson equation with the calculated ion densities to generate an updated set of potential values for the spatio-temporal grid. The iteration is started with the potential values of a self-consistent fluid model and terminates when the updates become sufficiently small, i.e. when self-consistency is achieved. A subsequent post-processing determines important quantities, in particular the phase-resolved and phase-averaged values of the ion energy and angular distributions and the total energy flux at the electrode. A drastic reduction of the computational effort compared with PIC calculations is achieved. As a first application of the new model, the influence of ion inertia on the dynamics of a collisionless sheath is studied and a comparison of the simulated ion energy distribution with published analytical solutions is performed.
Ionization and acceleration processes in a small, variable channel width, permanent-magnet Hall thruster
Authors: Mazouffre S , Bourgeois G , Dannenmayer K , Lejeune A
Published: April 2012

A 200 W-class permanent-magnet Hall thruster has been operated with different channel widths. A series of experiments have been carried out for each geometry over a broad range of propellant mass flow rates and applied voltages to investigate the impact of a channel cross-section area variation on discharge and plume properties. Measurement outcomes allow calculation of several quantities, namely the propellant utilization, the beam voltage, the equilibrium wall temperature and the energy flux towards the walls. This study reveals that widening the channel of a low-power Hall thruster enhances ionization and acceleration processes and broadens the operating envelope. Two mechanisms are proposed to explain experimental observations. The surface-to-volume ratio decreases with h, which reduces wall-losses. The magnetic field strength near walls increases with h, which leads to a better plasma confinement.
Study on the effect of Pb partial substitution for Te on the thermoelectric properties of La3Te4−xPbx materials
Authors: Gao H L , Zhu T J , Wang H , Ren Z F , Zhao X B
Published: April 2012

The effect of Pb in La3Te4−x
Pb
x
on the thermoelectric properties in the temperature range 300–1100 K was studied on samples synthesized by the melting, ball milling and hot-pressing method. The samples crystallize in the Th3P4structure. A small amount of Pb substitution for Te in La3Te4 reduced the electrical conductivity, but the impurity phase introduced by more Pb significantly enhanced the electrical conductivity. The electrical conductivity of the La3Te3.6Pb0.4 sample reached 2.06 × 105 S m−1 at room temperature. The expansion of crystal lattice confirmed from x-ray diffraction patterns and the slight reduction in electrical conductivity all verify the fact that Pb substitutes a Te site when x is small. The Seebeck coefficient increases linearly with temperature for all samples. While the thermal conductivity varies slightly with temperature, the lattice thermal conductivity approaches the minimum value at high temperatures. For La3Te3.7Pb0.3, a power factor of 1.4 × 10−3 W m−1 K−2 at 1100 K was achieved with a thermal conductivity of 1.86 W m−1 K−1, giving a maximum figure-of-merit ZT ≈ 0.8 at 1100 K.
Intra-band gap in Lamb modes propagating in a periodic solid structure
Authors: Pierre J , Rénier M , Bonello B , Hladky-Hennion A-C
Published: April 2012

A laser ultrasonic technique is used to measure the dispersion of Lamb waves at a few MHz, propagating in phononic crystals made of dissymmetric air inclusions drilled throughout silicon plates. It is shown that the specific shape of the inclusions is at the origin of the intra-band gap that opens within the second Brillouin zone, at the crossing of both flexural and dilatational zero-order modes. The magnitude of the intra-band gap is measured as a function of the dissymmetry rate of the inclusions. Experimental data and the computed dispersion curves are in very good agreement.
Investigations of laser-sustained plasma and its role in laser nitriding of titanium
Authors: Nassar A R , Akarapu R , Copley S M , Todd J A
Published: April 2012

Laser-sustained plasma (LSP) and CCD imaging of reactant species were employed to investigate the role of near-surface plasma in CO2 laser nitriding of titanium in open atmosphere. Insights were gained regarding the role of plasma processes and the role of reactive nitriding species in the nitriding process. Studies of single nitrided trails have identified the following regimes, as a function of LSP off-focal distance and beam translation speed, characterized by (1) the formation of heavily oxidized surfaces, (2) the formation of titanium nitride (TiN) nanoparticulate, (3) nitride formation in the absence of a surface-struck or LSP and (4) the formation of near-stoichiometric, oxide-free TiN surfaces with a LSP. For the first time it will be shown that the LSP can access nitriding conditions beyond those achieved with surface-struck plasma (or in the absence of plasma) to produce uniform, near-stoichiometric, titanium nitride coatings.
Universal bounds for eigenvalues of a buckling problem II
Authors: Cheng Qing-Ming , Yang Hongcang
Published: April 2012

In this paper, we investigate universal estimates for eigenvalues of a buckling problem. For a bounded domain in a Euclidean space, we give a positive contribution for obtaining a sharp universal inequality for eigenvalues of the buckling problem. For a domain in the unit sphere, we give an important improvement on the results of Wang and Xia.
Time-to-Event Analysis of Longitudinal Follow-up of a Survey: Choice of the Time-scale
Authors: Korn Edward L. , Graubard Barry I. , Midthune Douglas
Published: April 2012

Following individuals sampled in a large-scale health survey for the development of diseases and/or death offers the opportunity to assess the prognostic significance of various risk factors. The proportional hazards regression model, which allows for the control of covariates, is frequently used for the analysis of such data. The authors discuss the appropriate time-scale for such regression models, and they recommend that age rather than time since the baseline survey (time-on-study) be used. Additionally, with age as the time-scale, control for calendar-period and/or birth cohort effects can be achieved by stratifying the model on birth cohort. Because, as discussed by the authors, many published analyses have used regression models with time-on-study as the time-scale, it is important to assess the magnitude of the error incurred from this type of incorrect modeling. The authors provide simple conditions for when incorrect use of time-on-study as the time-scale will nevertheless yield approximately unbiased proportional hazards regression coefficients. Examples are given using data from the first National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Followup Study. Additional issues concerning the analysis of longitudinal follow-up of survey data are briefly discussed. Am J Epidemiol 1997; 145: 72–80
A web server to locate periodicities in a sequence
Authors: Pasquier CM , Promponas VI , Varvayannis NJ , Hamodrakas SJ
Published: April 2012

Summary : FT is a tool written in C++, which implements the Fourier analysis method to locate periodicities in aminoacid or DNA sequences. It is provided for free public use on a WWW server with a Java interface. Availability : The server address is http://o2.db. uoa.gr/FT Contact : shamodr@atlas.uoa.gr
The P25 Pathogenicity Factor of Beet necrotic yellow vein virus Targets the Sugar Beet 26S Proteasome Involved in the Induction of a Hypersensitive Resistance Response via Interaction with an F-box Protein
Authors: Thiel Heike , Hleibieh Kamal , Gilmer David , Varrelmann Mark
Published: April 2012

P25, a Beet necrotic yellow vein virus (BNYVV) pathogenicity factor, interacts with a sugar beet protein with high homology to Arabidopsis thaliana kelch repeat containing F-box family proteins (FBK) of unknown function in yeast. FBK are members of the Skp1-Cullin-F-box (SCF) complex that mediate protein degradation. Here, we confirm this sugar beet FBK–P25 interaction in vivo and in vitro and provide evidence for in planta interaction and similar subcellular distribution in Nicotiana tabacum leaf cells. P25 even interacts with an FBK from A. thaliana, a BNYVV nonhost. FBK functional classification was possible by demonstrating the interaction with A. thaliana orthologs of Skp1-like (ASK) genes, a member of the SCF E3 ligase. By means of a yeast two-hybrid bridging assay, a direct effect of P25 on SCF-complex formation involving ASK1 protein was demonstrated. FBK transient Agrobacterium tumefaciens–mediated expression in N. benthamiana leaves induced a hypersensitive response. The full-length F-box protein consists of one F-box domain followed by two kelch repeats, which alone were unable to interact with P25 in yeast and did not lead to cell-death induction. The results support the idea that P25 is involved in virus pathogenicity in sugar beet and suggest suppression of resistance response.
Trans-oceanic host dispersal explains high seabird tick diversity on Cape Verde islands
Authors: Gómez-Díaz E. , Morris-Pocock J. A. , González-Solís J. , McCoy K. D.
Published: April 2012

Parasites represent ideal models for unravelling biogeographic patterns and mechanisms of diversification on islands. Both host-mediated dispersal and within-island adaptation can shape parasite island assemblages. In this study, we examined patterns of genetic diversity and structure of
Ornithodoros
seabird ticks within the Cape Verde Archipelago in relation to their global phylogeography. Contrary to expectations, ticks from multiple, geographically distant clades mixed within the archipelago. Trans-oceanic colonization via host movements probably explains high local tick diversity, contrasting with previous research that suggests little large-scale dispersal in these birds. Although host specificity was not obvious at a global scale, host-associated genetic structure was found within Cape Verde colonies, indicating that post-colonization adaptation to specific hosts probably occurs. These results highlight the role of host metapopulation dynamics in the evolutionary ecology and epidemiology of avian parasites and pathogens.
Modelling deuterium labelling of lymphocytes with temporal and/or kinetic heterogeneity
Authors: De Boer Rob J. , Perelson Alan S. , Ribeiro Ruy M.
Published: April 2012

To study the kinetics of lymphocytes, models have divided the cell population into subpopulations with different turnover rates. These have been called ‘kinetic heterogeneity models’ so as to distinguish them from ‘temporal heterogeneity models’, in which a cell population may have different turnover rates at different times, e.g. when resting versus when activated. We model labelling curves for temporally heterogeneous populations, and predict that they exhibit equal biphasic up- and downslopes. We show when cells divide only once upon activation, these slopes are dominated by the slowest exponent, yielding underestimates of the average turnover rate. When cells undergo more than one division, the labelling curves allow fitting of the two exponential slopes in the temporal heterogeneity model. The same data can also be described with a two-compartment kinetic heterogeneity model. In both instances, the average turnover rate is correctly estimated. Because both models assume a different cell biology but describe the data equally well, the parameters of either model have no simple biological interpretation, as each parameter could reflect a combination of parameters of another biological process. Thus, even if there are sufficient data to reliably estimate all exponentials, one can only accurately estimate an average turnover rate. We illustrate these issues by re-fitting labelling data from healthy and HIV-infected individuals.
Statistical approach to normalization of feature vectors and clustering of mixed datasets
Authors: Suarez-Alvarez Maria M. , Pham Duc-Truong , Prostov Mikhail Y. , Prostov Yuriy I.
Published: April 2012

Normalization of feature vectors of datasets is widely used in a number of fields of data mining, in particular in cluster analysis, where it is used to prevent features with large numerical values from dominating in distance-based objective functions. In this study, a unified statistical approach to normalization of all attributes of mixed databases, when different metrics are used for numerical and categorical data, is proposed. After the proposed normalization, the contributions of both numerical and categorical attributes to a specified objective function are statistically the same. Formulae for the statistically normalized Minkowski mixedp-metrics are given in an explicit way. It is shown that the classicz-score standardization and the min–max normalization are particular cases of the statistical normalization, when the objective function is, respectively, based on the Euclidean or the Tchebycheff (Chebyshev) metrics. Finally, clustering of several benchmark datasets is performed with non-normalized and introduced normalized mixed metrics using either thek-prototypes (forp=2) or another algorithm (forp≠2).
Wrapping the cube and other polyhedra
Authors: Tarnai T. , Kovács F. , Fowler P. W. , Guest S. D.
Published: April 2012

An infinite series of twofold, two-way weavings of the cube, corresponding to ‘wrappings’, or double covers of the cube, is described with the aid of the two-parameter Goldberg–Coxeter construction. The strands of all such wrappings correspond to the central circuits (CCs) of octahedrites (four-regular polyhedral graphs with square and triangular faces), which for the cube necessarily have octahedral symmetry. Removing the symmetry constraint leads to wrappings of other eight-vertex convex polyhedra. Moreover, wrappings of convex polyhedra with fewer vertices can be generated by generalizing from octahedrites toi-hedrites, which additionally include digonal faces. When the strands of a wrapping correspond to the CCs of a four-regular graph that includes faces of size greater than 4, non-convex ‘crinkled’ wrappings are generated. The various generalizations have implications for activities as diverse as the construction of woven-closed baskets and the manufacture of advanced composite components of complex geometry.
Effects of diurnally oscillatingpCO2on the calcification and survival of coral recruits
Authors: Dufault Aaron M. , Cumbo Vivian R. , Fan Tung-Yung , Edmunds Peter J.
Published: April 2012

Manipulative studies have demonstrated that ocean acidification (OA) is a threat to coral reefs, yet no experiments have employed diurnal variations inpCO2that are ecologically relevant to many shallow reefs. Two experiments were conducted to test the response of coral recruits (less than 6 days old) to diurnally oscillatingpCO2; one exposing recruits for 3 days to ambient (440 µatm), high (663 µatm) and diurnally oscillatingpCO2on a natural phase (420–596 µatm), and another exposing recruits for 6 days to ambient (456 µatm), high (837 µatm) and diurnally oscillatingpCO2on either a natural or a reverse phase (448–845 µatm). In experiment I, recruits exposed to natural-phased diurnally oscillatingpCO2grew 6–19% larger than those in ambient or highpCO2. In experiment II, recruits in both high and natural-phased diurnally oscillatingpCO2grew 16 per cent larger than those at ambientpCO2, and this was accompanied by 13–18% higher survivorship; the stimulatory effect on growth of oscillatorypCO2was diminished by administering highpCO2during the day (i.e. reverse-phased). These results demonstrate that coral recruits can benefit from ecologically relevant fluctuations inpCO2and we hypothesize that the mechanism underlying this response is highlypCO2-mediated, night-time storage of dissolved inorganic carbon that fuels daytime calcification.
Risk and the evolution of human exchange
Authors: Kaplan Hillard S. , Schniter Eric , Smith Vernon L. , Wilson Bart J.
Published: April 2012

Compared with other species, exchange among non-kin is a hallmark of human sociality in both the breadth of individuals and total resources involved. One hypothesis is that extensive exchange evolved to buffer the risks associated with hominid dietary specialization on calorie dense, large packages, especially from hunting. ‘Lucky’ individuals share food with ‘unlucky’ individuals with the expectation of reciprocity when roles are reversed. Cross-cultural data provide prima facie evidence of pair-wise reciprocity and an almost universal association of high-variance (HV) resources with greater exchange. However, such evidence is not definitive; an alternative hypothesis is that food sharing is really ‘tolerated theft’, in which individuals possessing more food allow others to steal from them, owing to the threat of violence from hungry individuals. Pair-wise correlations may reflect proximity providing greater opportunities for mutual theft of food. We report a laboratory experiment of foraging and food consumption in a virtual world, designed to test the risk-reduction hypothesis by determining whether people form reciprocal relationships in response to variance of resource acquisition, even when there is no external enforcement of any transfer agreements that might emerge. Individuals can forage in a high-mean, HV patch or a low-mean, low-variance (LV) patch. The key feature of the experimental design is that individuals can transfer resources to others. We find that sharing hardly occurs after LV foraging, but among HV foragers sharing increases dramatically over time. The results provide strong support for the hypothesis that people are pre-disposed to evaluate gains from exchange and respond to unsynchronized variance in resource availability through endogenous reciprocal trading relationships.
Syntactic structure and geographical dialects in the songs of male rock hyraxes
Authors: Kershenbaum Arik , Ilany Amiyaal , Blaustein Leon , Geffen Eli
Published: April 2012

Few mammalian species produce vocalizations that are as richly structured as bird songs, and this greatly restricts the capacity for information transfer. Syntactically complex mammalian vocalizations have been previously studied only in primates, cetaceans and bats. We provide evidence of complex syntactic vocalizations in a small social mammal: the rock hyrax (
Procavia capensis
: Hyracoidea). We adopted three algorithms, commonly used in genetic sequence analysis and information theory, to examine the order of syllables in hyrax calls. Syntactic dialects exist, and the syntax of hyrax calls is significantly different between different regions in Israel. Call syntax difference is positively correlated to geographical distance over short distances. No correlation is found over long distances, which may reflect limited dispersal movement. These findings indicate that rich syntactic structure is more common in the vocalizations of mammalian taxa than previously thought and suggest the possibility of vocal production learning in the hyrax.
A sex-specific trade-off between mating preferences for genetic compatibility and body size in a cichlid fish with mutual mate choice
Authors: Thünken Timo , Meuthen Denis , Bakker Theo C. M. , Baldauf Sebastian A.
Published: April 2012

Mating preferences for genetic compatibility strictly depend on the interplay of the genotypes of potential partners and are therein fundamentally different from directional preferences for ornamental secondary sexual traits. Thus, the most compatible partner is on average not the one with most pronounced ornaments and vice versa
.
Hence, mating preferences may often conflict. Here, we present a solution to this problem while investigating the interplay of mating preferences for relatedness (a compatibility criterion) and large body size (an ornamental or quality trait). In previous experiments, both sexes of
Pelvicachromis taeniatus
, a cichlid fish with mutual mate choice, showed preferences for kin and large partners when these criteria were tested separately. In the present study, test fish were given a conflicting choice between two potential mating partners differing in relatedness as well as in body size in such a way that preferences for both criteria could not simultaneously be satisfied. We show that a sex-specific trade-off occurs between mating preferences for body size and relatedness. For females, relatedness gained greater importance than body size, whereas the opposite was true for males. We discuss the potential role of the interplay between mating preferences for relatedness and body size for the evolution of inbreeding preference.
Speciation with gene flow in a heterogeneous virtual world: can physical obstacles accelerate speciation?
Authors: Golestani Abbas , Gras Robin , Cristescu Melania
Published: April 2012

The origin of species remains one of the most controversial and least understood topics in evolution. While it is being widely accepted that complete cessation of gene-flow between populations owing to long-lasting geographical barriers results in a steady, irreversible increase of divergence and eventually speciation, the extent to which various degrees of habitat heterogeneity influences speciation rates is less well understood. Here, we investigate how small, randomly distributed physical obstacles influence the distribution of populations and species, the level of population connectivity (e.g. gene flow), as well as the mode and tempo of speciation in a virtual ecosystem composed of prey and predator species. We adapted an existing individual-based platform, EcoSim, to allow fine tuning of the gene flow's level between populations by adding various numbers of obstacles in the world. The platform implements a simple food chain consisting of primary producers, herbivores (prey) and predators. It allows complex intra- and inter-specific interactions, based on individual evolving behavioural models, as well as complex predator–prey dynamics and coevolution in spatially homogenous and heterogeneous worlds. We observed a direct and continuous increase in the speed of evolution (e.g. the rate of speciation) with the increasing number of obstacles in the world. The spatial distribution of species was also more compact in the world with obstacles than in the world without obstacles. Our results suggest that environmental heterogeneity and other factors affecting demographic stochasticity can directly influence speciation and extinction rates.
Differential regulation of glutamic acid decarboxylase gene expression after extinction of a recent memory vs. intermediate memory
Authors: Sangha Susan , Ilenseer Jasmin , Sosulina Ludmila , Lesting Jörg , Pape Hans-Christian
Published: April 2012

Extinction reduces fear to stimuli that were once associated with an aversive event by no longer coupling the stimulus with the aversive event. Extinction learning is supported by a network comprising the amygdala, hippocampus, and prefrontal cortex. Previous studies implicate a critical role of GABA in extinction learning, specifically the GAD65 isoform of the GABA synthesizing enzyme glutamic acid decarboxylase (GAD). However, a detailed analysis of changes in gene expression of GAD in the subregions comprising the extinction network has not been undertaken. Here, we report changes in gene expression of the GAD65 and GAD67 isoforms of GAD, as measured by relative quantitative real-time RT-PCR, in subregions of the amygdala, hippocampus, and prefrontal cortex 24–26 h after extinction of a recent (1-d) or intermediate (14-d) fear memory. Our results show that extinction of a recent memory induces a down-regulation of Gad65 gene expression in the hippocampus (CA1, dentate gyrus) and an up-regulation of Gad67 gene expression in the infralimbic cortex. Extinguishing an intermediate memory increased Gad65 gene expression in the central amygdala. These results indicate a differential regulation of Gad gene expression after extinction of a recent memory vs. intermediate memory.
The p53 target gene TRIM22 directly or indirectly interacts with the translation initiation factor eIF4E and inhibits the binding of eIF4E to eIF4G
Authors: Petersson Jessica , Ageberg Malin , Sandén Carl , Olofsson Tor , Gullberg Urban , Drott Kristina
Published: April 2012

Background information

The interferon (IFN)‐inducible protein TRIM22 (Staf50) is a member of the tripartite motif protein family and has been suggested a role in the regulation of viral replication as well as of protein ubiquitylation. In addition, we have previously shown that TRIM22 is a direct target gene for the tumour suppressor p53. Consistently, over‐expression of TRIM22 inhibits the clonogenic growth of monoblastic U937 cells, suggesting anti‐proliferative or cell death‐inducing effects.

Results

Here, we demonstrate that TRIM22 directly or indirectly interacts with the eukaryotic translation initiation factor (eIF)4E, and inhibits the binding of eIF4E to eIF4G, thus disturbing the assembly of the eIF4F complex, which is necessary for cap‐dependent translation. Furthermore, TRIM22 exerts a repressive effect on luciferase reporter protein levels and to some extent on radiolabelled methionine incorporation. Even though all nuclear mRNAs are capped, some are more dependent on eIF4F than others for translation. The translation of one of these mRNAs, IRF‐7C, was indeed found to be repressed in the presence of TRIM22.

Conclusions

Our data suggest TRIM22 to repress protein translation preferably of some specific mRNAs. Taken together, we show that TRIM22 represses translation by inhibiting the binding of eIF4E to eIF4G, suggesting a mechanism for regulation of protein translation, which may be of importance in response to p53 and/or IFN signalling.
Simple and specific detection of Bordetella holmesii by using a loop‐mediated isothermal amplification assay
Authors: Otsuka Nao , Yoshino Shuji , Kawano Kimiko , Toyoizumi‐Ajisaka Hiromi , Shibayama Keigo , Kamachi Kazunari
Published: April 2012

A loop‐mediated isothermal amplification (LAMP) assay for simple detection of Bordetella holmesii was developed. This assay discriminates between B. holmesii and other Bordetella species and successfully detect B. holmesii DNA in nasopharyngeal swab samples from subjects with suspected pertussis. The LAMP assay results were in complete agreement with the results of previously published real‐time PCR assay, indicating that the former is a powerful tool for the accurate diagnosis and surveillance of B. holmesii.
A genome‐wide scan for quantitative trait loci affecting respiratory disease and immune capacity in Landrace pigs
Authors: Okamura T. , Onodera W. , Tayama T. , Kadowaki H. , Kojima‐Shibata C. , Suzuki E. , Uemoto Y. , Mikawa S. , Hayashi T. , Awata T. , Fujishima‐Kanaya N. , Mikawa A. , Uenishi H. , Suzuki K.
Published: April 2012

Respiratory disease is the most important health concern for the swine industry. Genetic improvement for disease resistance is challenging because of the difficulty in obtaining good phenotypes related with disease resistance; however, identification of genes or markers associated with disease resistance can help in the genetic improvement of pig health. The purpose of our study was to investigate whether quantitative trait loci (QTL) associated with disease resistance were segregated in a purebred population of Landrace pigs that had been selected for meat production traits and mycoplasmal pneumonia of swine (MPS) scores over five generations. We analysed 1395 pigs from the base to the fifth generation of this population. Two respiratory disease traits [MPS scores and atrophic rhinitis (AR) scores] and 11 immune‐capacity traits were measured in 630–1332 animals at 7 weeks of age and when the animal's body weight reached 105 kg. Each of the pigs, except sires in the base population, was genotyped using 109 microsatellite markers, and then, QTL analysis of the full‐sib family population with a multi‐generational pedigree structure was performed. Variance component analysis was used to detect QTL associated with MPS or AR scores, and the logarithm of odds (LOD) score and genotypic heritability of the QTL were estimated. Five significant (LOD > 2.51) and 18 suggestive (LOD > 1.35) QTL for respiratory disease traits and immune‐capacity traits were detected. The significant QTL for Log‐MPS score, located on S. scrofa chromosome 2, could explain 87% of the genetic variance of this score in this analysis. This is the first report of QTL associated with respiratory disease lesions.
A rare fraction of drug‐resistant follicular lymphoma cancer stem cells interacts with follicular dendritic cells to maintain tumourigenic potential
Authors: Lee Chung‐Gi , Das Bikul , Lin Tara L. , Grimes Chelsea , Zhang Xin , Lavezzi Tracey , Huang Li , Cole John , Yau Lillian , Li Li
Published: April 2012

Follicular lymphoma (FL) comprises nearly 25% of non‐Hodgkin lymphoma cases and is clinically characterized by initial sensitivity to chemotherapy followed by relapse. FL stroma contains a special type of stromal cell found in the germinal centre of lymph nodes—the follicular dendritic cell (FDC). We first isolated tumourigenic cells from the FL cell line FLK‐1 by side population (SP) technique, and found that SP cells, which express ABCG2, were enriched by chemotherapy and radiation treatments. In vitro, SP cells were attracted by and adhered to FDCs through chemokine (C‐X‐C motif) ligand 12/chemokine (C‐X‐C motif) receptor 4 (CXCL12/CXCR4) signalling. In vivo, limiting dilution assays showed SP cells were highly enriched in cancer stem cells (CSC), but required FDC for tumour formation in non‐obese diabetic/severe combined immunodeficiency mice. Treatment with AMD3100, a specific CXCL12/CXCR4 inhibitor, eliminated tumour growth. These findings were then verified with FL cells isolated from an FL patient's ascitic fluid (FLA‐1). Finally, we detected the ABCG2 expressing lymphoma cells in FL clinical specimens. Thus, we found that the highly tumourigenic FL cells having CSC‐like activities (FL‐SC) interact with FDCs in a CXCL12/CXCR4 dependent manner to resist chemotherapy. Our results indicate the importance of FL‐SC and niche cell signalling in maintaining tumourigenicity. These signals represent novel targets for CSC eradication.
Ethinyl estradiol–drospirenone vs ethinyl estradiol–drospirenone plus metformin in the treatment of lean women with polycystic ovary syndrome
Authors: Cinar Nese , Harmanci Ayla , Bayraktar Miyase , Yildiz Bulent O.
Published: April 2012

Objective

Oral contraceptive use might be associated with cardiometabolic risk in PCOS. We aimed to compare the effects of ethinyl estradiol–drospirenone (EE/DRSP) alone vs EE/DRSP plus metformin on clinical and cardiometabolic parameters in PCOS.

Design

Prospective observational study.

Patients

Forty‐five lean patients with PCOS who received EE/DRSP (30 μg/3 mg) (n = 25) or EE/DRSP plus metformin (1700 mg/day) (n = 20) and 45 BMI‐matched healthy controls.

Measurement

BMI, waist‐to‐hip ratio (WHR), hirsutism scores, androgens, lipids, glucose and insulin levels during an OGTT were measured before and after 6 months of treatment in patients and compared to controls.

Results

At baseline, patients with PCOS showed similar glucose, insulin and lipids but increased 2 h glucose values compared to controls. Hirsutism scores and free androgen index decreased in both treatment groups. BMI and WHR did not show any change in the EE/DRSP group, while metformin addition resulted in a decrease in BMI. Lipid levels increased in both groups. Glucose and insulin parameters did not change in any group, but metformin addition compared to EE/DRSP alone significantly decreased waist circumference, fasting insulin and HOMA‐IR. After‐treatment values for both EE/DRSP alone and in combination with metformin compared to the control group showed increased 2 h glucose and increased lipids in patients with PCOS.

Conclusion

EE/DRSP alone or in combination with metformin improves clinical and biochemical hyperandrogenism in lean PCOS. Both treatments similarly alter lipid profile. EE/DRSP alone does not affect insulin sensitivity, whereas combining EE/DRSP with metformin might improve it.