bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of the interfacial tension of complex coacervates using field-theoretic simulations
Authors: Riggleman Robert A. , Kumar Rajeev , Fredrickson Glenn H.
Published: January 2012

Complex coacervation, a liquid-liquid phase separation that occurs when two oppositely charged polyelectrolytes are mixed in a solution, has the potential to be exploited for many emerging applications including wet adhesives and drug delivery vehicles. The ultra-low interfacial tension of coacervate systems against water is critical for such applications, and it would be advantageous if molecular models could be used to characterize how various system properties (e.g., salt concentration) affect the interfacial tension. In this article we use field-theoretic simulations to characterize the interfacial tension between a complex coacervate and its supernatant. After demonstrating that our model is free of ultraviolet divergences (calculated properties converge as the collocation grid is refined), we develop two methods for calculating the interfacial tension from field-theoretic simulations. One method relies on the mechanical interpretation of the interfacial tension as the interfacial pressure, and the second method estimates the change in free energy as the area between the two phases is changed. These are the first calculations of the interfacial tension from full field-theoretic simulation of which we are aware, and both the magnitude and scaling behaviors of our calculated interfacial tension agree with recent experiments.
Experimental and theoretical investigation of the triple differential cross section for electron impact ionization of pyrimidine molecules
Authors: Builth-Williams J. D. , Bellm S. M. , Jones D. B. , Chaluvadi Hari , Madison D. H. , Ning C. G. , Lohmann B. , Brunger M. J.
Published: January 2012

Cross-section data for electron impact induced ionization of bio-molecules are important for modelling the deposition of energy within a biological medium and for gaining knowledge of electron driven processes at the molecular level. Triply differential cross sections have been measured for the electron impact ionization of the outer valence 7b2 and 10a1 orbitals of pyrimidine, using the (e, 2e) technique. The measurements have been performed with coplanar asymmetric kinematics, at an incident electron energy of 250 eV and ejected electron energy of 20 eV, for scattered electron angles of −5°, −10°, and −15°. The ejected electron angular range encompasses both the binary and recoil peaks in the triple differential cross section. Corresponding theoretical calculations have been performed using the molecular 3-body distorted wave model and are in reasonably good agreement with the present experiment.
X-ray diagnostics of runaway electrons generated during nanosecond discharge in gas at elevated pressures
Authors: Yatom S. , Levko D. , Gleizer J. Z. , Vekselman V. , Krasik Ya. E.
Published: January 2012

The properties of high-energy runaway electrons generated during a nanosecond discharge in an air filled diode at pressures up to 3 × 105 Pa were studied using x-ray absorption spectroscopy. The results of studies of the discharge at different pressures and with different lengths of cathode-anode gap allow an insight into the factors that influence the energy distribution of runaway electrons. Energy distribution functions for runaway electrons produced in particle-in-cell simulation were used to create the x-ray attenuation curves via a computer-assisted technique simulating the generation of x-ray by energetic electrons. The simulated attenuation curves were compared to experimental results.
Raman and x-ray photoelectron spectroscopy study of ferroelectric switching in Pb(Nb,Zr,Ti)O3 thin films
Authors: Ramos-Moore E. , Ferrari P. , Diaz-Droguett D. E. , Lederman D. , Evans J. T.
Published: January 2012

The ferroelectric switching process in Pb(Nb,Zr,Ti)O3 thin films was studied by performing Ramanspectroscopy and x-ray photoelectron spectroscopy (XPS). Switching was achieved using a macroscopic polarization experiment above and below the Curie temperature. Two samples in opposite switching states were obtained and characterized in order to correlate both vibrational-bands distortions of the bulk and changes in the elemental states of the surface. We have assigned the symmetrical A1(2TO) (332 cm−1) and A1(3TO) (603 cm−1) vibrational modes to the ferroelectric phase. Their corresponding peaks-area showed symmetrical behavior when the sample was polarized in opposite directions, while the quantity of phonons associated to the ferroelectric phase was conserved. We found that binding energies in the XPS signals of the Ti 2p, Nb 3d, Zr 3d, and Pb 4f levels increased when comparing to the values found in a non-polarized sample. Moreover, a high population of oxygen vacancies diffused to the surface of the ferroelectric capacitor under the application of external electric fields. Our novel results show the correlation between vibrational and ferroelectric behaviors and highlight the possibility to perform in situ treatments to decrease thedegradation of current technological capacitors.
Quantum and thermo-mechanical noise squeezing in nanoresonators: A comparative study
Authors: Xu Yang , Zhu Kaicheng , Yan Sheping , Jin Zhonghe , Wang Yuelin , Chen Hongsheng , Luo Jikui , Yu Bin
Published: January 2012

Based on theoretical modeling, we performed comprehensive investigation on the quantum and thermomechanical noise squeezing effect in nanoresonators made by two platform material systems: silicon and graphene. We discovered that quantum noise squeezing plays an important role in the effort to improve signal-to-noise ratio in graphene-based nanoresonators. The research suggests a viable strategy for implementing graphene-based nanoscale transducers with ultra-high sensitivity that can be potentially utilized to detect a variety of sensing targets, including atomic force, single biological molecule, and gravitational wave.
A torsion balance for impulse and thrust measurements of micro-Newton thrusters
Authors: Yang Yuan-Xia , Tu Liang-Cheng , Yang Shan-Qing , Luo Jun
Published: January 2012

This paper reports the performance of a torsion-type thrust stand suitable for studies of micro-Newton thrusters, which is developed for ground testing the micro-Newton thruster in Chinese Test of the Equivalence Principle with Optical readout space mission. By virtue of specially suspending design and precise assembly of torsion balance configuration, the thrust stand with load capacity up to several kilograms is able to measure the impulse bit up to 1350 μNs with a resolution of 0.47 μNs, and the average thrust up to 264 μN with a resolution of 0.09 μN in both open and close loop operation. A pulsed plasma thruster, the preliminary prototype developed for Chinese TEPO space mission, is tested by the thrust stand, and the results reveal that the average impulse bit per pulse is measured to be 58.4 μNs with a repeatability of about 5%.
Structural and optical studies of nitrogen incorporation into GaSb-based GaInSb quantum wells
Authors: Nair Hari P. , Crook Adam M. , Yu Kin M. , Bank Seth R.
Published: January 2012

We investigate the incorporation of nitrogen into (Ga,In)Sb grown on GaSb and report room temperature photoluminescence from GaInSb(N) quantum wells. X-ray diffraction and channeling nuclear reaction analysis, together with Rutherford backscattering, were employed to identify the optimal molecular beam epitaxial growth conditions that minimized the incorporation of non-substitutional nitrogen into GaNSb. Consistent with this hypothesis, GaInSb(N) quantum wells grown under the conditions that minimized non-substitutional nitrogen exhibited room temperature photoluminescence, indicative of significantly improved radiative efficiency. Further development of this material system could enable type-I laser diodes emitting throughout the (3-5 μm) wavelength range.
Optimizing non-radiative energy transfer in hybrid colloidal-nanocrystal/silicon structures by controlled nanopillar architectures for future photovoltaic cells
Authors: Seitz O. , Caillard L. , Nguyen H. M. , Chiles C. , Chabal Y. J. , Malko A. V.
Published: January 2012

To optimize colloidal nanocrystals/Si hybrid structures, nanopillars are prepared and organized via microparticle patterning and Si etching. A monolayer of CdSe nanocrystals is then grafted on the passivated oxide-free nanopillar surfaces, functionalized with carboxy-alkyl chain linkers. This process results to a negligible number of non-radiative surface state defects with a tightly controlled separation between the nanocrystals and Si. Steady-state and time-resolved photoluminescence measurements confirm the close-packing nanocrystal arrangement and the dominance of non-radiative energy transfer from nanocrystals to Si. We suggest that radially doped p-n junction devices based on energy transfer offer a viable approach for thin film photovoltaic devices.
444.9 nm semipolar (112¯2) laser diode grown on an intentionally stress relaxed InGaN waveguiding layer
Authors: Shan Hsu Po , Hardy Matthew T. , Wu Feng , Koslow Ingrid , Young Erin C. , Romanov Alexey E. , Fujito Kenji , Feezell Daniel F. , DenBaars Steven P. , Speck James S. , Nakamura Shuji
Published: January 2012

We demonstrate an electrically injected semipolar (112¯2) laser diode (LD) grown on an intentionally stress relaxed n-In0.09Ga0.91N waveguiding layer. Detrimental effects of misfit dislocations (MDs) in the proximity of the active region were effectively suppressed by utilizing a p/n-Al0.2Ga0.8N electron/hole blocking layer between the dislocated heterointerfaces and the active region. The threshold current density of the LD was ∼20.3 kA/cm2 with a lasing wavelength of 444.9 nm. This LD demonstrates an alternative approach in semipolar AlInGaN LD waveguide design where the thickness and composition of the waveguiding and/or cladding layers are not limited by the critical thickness for MD formation.
Formation mechanism of cellular structures during unidirectional growth of binary semiconductor Si-rich SiGe materials
Authors: Gotoh Raira , Fujiwara Kozo , Yang Xinbo , Koizumi Haruhiko , Nozawa Jun , Uda Satoshi
Published: January 2012

The formation mechanism of a cellular structure during the growth of Si-rich SiGe crystals was studied by in situ observation. We directly observed the morphological transformation of the crystal-melt interface during the unidirectional growth of Si-rich SiGe. It was found that the morphology of the interface transformed from a planar to a zigzag facets to a faceted cellular interface with increasing growth rate. It is clarified that Ge segregation at valleys of zigzag facets leads to the formation of a cellular structure in Si-rich SiGe crystals.
Probing band-tail states in silicon metal-oxide-semiconductor heterostructures with electron spin resonance
Authors: Jock R. M. , Shankar S. , Tyryshkin A. M. , He Jianhua , Eng K. , Childs K. D. , Tracy L. A. , Lilly M. P. , Carroll M. S. , Lyon S. A.
Published: January 2012

We present an electron spin resonance (ESR) approach to characterize shallow electron trapping in band-tail states at Si/SiO2 interfaces in metal-oxide-semiconductor (MOS) devices and demonstrate it on two MOS devices fabricated at different laboratories. Despite displaying similar low temperature (4.2 K) peak mobilities, our ESR data reveal a significant difference in the Si/SiO2 interface quality of these two devices, specifically an order of magnitude difference in the number of shallow trapped charges at the Si/SiO2 interfaces. Thus, our ESR method allows a quantitative evaluation of the Si/SiO2 interface quality at low electron densities, where conventional mobility measurements are not possible.
Carrier mobility measurement across a single grain boundary in polycrystalline silicon using an organic gate thin-film transistor
Authors: Hashimoto Masaki , Kanomata Kensaku , Momiyama Katsuaki , Kubota Shigeru , Hirose Fumihiko
Published: January 2012

In this study, we developed a measurement method for field-effect-carrier mobility across a single grain boundary in polycrystalline Si (poly Si) used for solar cell production by using an organic gate field-effect transistor (FET). To prevent precipitation and the diffusion of impurities affecting the electronic characteristics of the grain boundary, all the processing temperatures during FET fabrication were held below 150 °C. From the grain boundary, the field-effect mobility was measured at around 21.4 cm2/Vs at 297 K, and the temperature dependence of the field-effect mobility suggested the presence of a potential barrier of 0.22 eV at the boundary. The technique presented here is applicable for the monitoring of carrier conduction characteristics at the grain boundary in poly Si used for the production of solar cells.
Effects of cooperative ionic motion on programming kinetics of conductive-bridge memory cells
Authors: Jameson John R. , Gilbert Nad , Koushan Foroozan , Saenz Juan , Wang Janet , Hollmer Shane , Kozicki Michael
Published: January 2012

Cooperative ionic motion is identified as a key physical effect influencing the programming kinetics of Ag/GeS2/W conductive-bridge memory cells. Cooperative effects are suggested to cause the time required to program virgin cells to: (i) deviate from the exponential voltage dependence typically observed at high voltage if the GeS2 is very thin and (ii) increase dramatically at low voltage when programmed with a pulse train having a low duty cycle. A previously reported model is shown to account for both phenomena, and a kinetic Monte Carlo algorithm is described for making quantitative calculations.
Ultra-wideband surface acoustic wave resonator employing Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 crystals
Authors: Chen Jing , Liu Jiansong , Hashimoto Ken-ya , Omori Tatsuya , Ahn Changjun , Zhao Xiangyong , Luo Haosu
Published: January 2012

Theoretical analysis showed that high performance surface acoustic wave (SAW) resonator with an extremely large electromechanical coupling factor K2 could be realized on Y cut X propagating Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (YX-PIN-PMN-PT) substrate. A one-port SAW resonator was designed, fabricated, and characterized on Cu-grating/YX-PIN-PMN-PT substrate structure. The experimental results demonstrate that very large K2 of 57.3% is realizable. Such an extremely large K2 makes PIN-PMN-PT single crystal great potential for realizing wideband SAW filters and tunable SAW filters. The influence of inhomogeneity and instability of the domain structure on the fabricated resonators has been discussed thoroughly for further improvement of the devices.
The Australian sheep industry - undergoing transformation
Authors: Rowe J. B.
Published: January 2012

Changes in the sheep industry over the last 20 years represent a trend that is unlikely to be reversed. The farm gate value of wool production has decreased from over $6 billion to ~$2.5 billion and the value of sheep meat has increased from $0.5 to $2.2 billion. Wool and meat are now on an equal footing in terms of the economic value of each sector of the industry. Future profitability of both wool and sheep meat production depends on achieving a high rate of productivity gain and improving quality attributes valued by consumers. Wool and sheep meat cannot compete on price or volume with synthetics and cotton in the textile market or with chicken and pork in the meat market. Differentiation based on quality and consistency needs to be measurable and clearly understood by consumers. The combination of genetic selection and good management can deliver improved productivity gain. Skills development and training will be essential for the industry to fully utilise available knowledge and new technologies.
Using Australian Sheep Breeding Values to increase lean meat yield percentage
Authors: Gardner G. E. , Williams A. , Siddell J. , Ball A. J. , Mortimer S. , Jacob R. H. , Pearce K. L. , Hocking Edwards J. E. , Rowe J. B. , Pethick D. W.
Published: January 2012

This study describes the impact of Australian Sheep Breeding Values (ASBV) for post-weaning weight (PWWT), C-site fatness (PFAT) and eye muscle depth (PEMD) on lamb carcasses within the Australian Sheep Industry CRC Information Nucleus Flock. These results are taken from the 2007 drop progeny, consisting of ~2000 lambs slaughtered at a target weight of 21.5 kg. These lambs were the progeny of sires selected to ensure genetic diversity across various production traits. As expected, the PWWT ASBV increased weight at slaughter, and hot standard carcass weight. Dressing percentage was markedly improved by increasing PEMD ASBV, thus prime lamb producers will be maintaining an animal of similar weight on farm, but delivering a markedly larger carcass at slaughter. Lean meat yield % (LMY%) was highest in the progeny of sires with low PFAT ASBV, which decreased whole carcass fatness and increased muscularity. PWWT ASBV affected carcass composition but had little impact on LMY%, as the decreased fatness was largely offset by increased bone, with relatively little change in muscle content. Lastly, PEMD ASBV had little impact on whole carcass LMY%, but did appear to cause some level of muscle redistribution to the higher value loin cuts, in turn increasing the value of the carcass lean.
Design and role of an information nucleus in sheep breeding programs
Authors: van der Werf J. H. J. , Kinghorn B. P. , Banks R. G.
Published: January 2012

The Australian sheep Cooperative Research Centre has initiated an information nucleus with the aim to estimate genetic parameters for new traits, to undertake a large-scale whole-genome association study and to enhance the breeding values of breeding animals in commercial studs. This paper presents the rationale behind the current design factors to meet the main objectives. It then discusses the potential design of an information nucleus if it were a sustainable part of commercial sheep-breeding programs in the long term. Advantages of such an information nucleus are summarised and quantified where possible.
Microbial diversity determines the invasion of soil by a bacterial pathogen
Authors: van Elsas Jan Dirk , Chiurazzi Mario , Mallon Cyrus A. , Elhottovā Dana , Krištůfek Václav , Salles Joana Falcão
Published: January 2012

Natural ecosystems show variable resistance to invasion by alien species, and this resistance can relate to the species diversity in the system. In soil, microorganisms are key components that determine life support functions, but the functional redundancy in the microbiota of most soils has long been thought to overwhelm microbial diversity–function relationships. We here show an inverse relationship between soil microbial diversity and survival of the invading species
Escherichia coli
O157:H7, assessed by using the marked derivative strain T. The invader's fate in soil was determined in the presence of (
i
) differentially constructed culturable bacterial communities, and (
ii
) microbial communities established using a dilution-to-extinction approach. Both approaches revealed a negative correlation between the diversity of the soil microbiota and survival of the invader. The relationship could be explained by a decrease in the competitive ability of the invader in species-rich vs. species-poor bacterial communities, reflected in the amount of resources used and the rate of their consumption. Soil microbial diversity is a key factor that controls the extent to which bacterial invaders can establish.
Critical role for phosphoinositide 3-kinase gamma in parasite invasion and disease progression of cutaneous leishmaniasis
Authors: Cummings Hannah E. , Barbi Joseph , Reville Patrick , Oghumu Steve , Zorko Nicholas , Sarkar Anasuya , Keiser Tracy L. , Lu Bao , Rückle Thomas , Varikuti Sanjay , Lezama-Davila Claudio , Wewers Mark D. , Whitacre Caroline , Radzioch Danuta , Rommel Christian , Seveau Stéphanie , Satoskar Abhay R.
Published: January 2012

Obligate intracellular pathogens such as
Leishmania
specifically target host phagocytes for survival and replication. Phosphoinositide 3-kinase γ (PI3Kγ), a member of the class I PI3Ks that is highly expressed by leukocytes, controls cell migration by initiating actin polymerization and cytoskeletal reorganization, which are processes also critical for phagocytosis. In this study, we demonstrate that class IB PI3K, PI3Kγ, plays a critical role in pathogenesis of chronic cutaneous leishmaniasis caused by
L. mexicana
. Using the isoform-selective PI3Kγ inhibitor, AS-605240 and PI3Kγ gene-deficient mice, we show that selective blockade or deficiency of PI3Kγ significantly enhances resistance against
L. mexicana
that is associated with a significant suppression of parasite entry into phagocytes and reduction in recruitment of host phagocytes as well as regulatory T cells to the site of infection. Furthermore, we demonstrate that AS-605240 is as effective as the standard antileishmanial drug sodium stibogluconate in treatment of cutaneous leishmaniasis caused by
L. mexicana
. These findings reveal a unique role for PI3Kγ in
Leishmania
invasion and establishment of chronic infection, and demonstrate that therapeutic targeting of host pathways involved in establishment of infection may be a viable strategy for treating infections caused by obligate intracellular pathogens such as
Leishmania
.
Chlamydophila pneumoniae
phospholipase D (CpPLD) drives Th17 inflammation in human atherosclerosis
Authors: Benagiano Marisa , Munari Fabio , Ciervo Alessandra , Amedei Amedeo , Paccani Silvia Rossi , Mancini Fabiola , Ferrari Mauro , Della Bella Chiara , Ulivi Camilla , D'Elios Sofia , Baldari Cosima T. , Prisco Domenico , de Bernard Marina , D'Elios Mario M.
Published: January 2012

Phospholipases are produced from bacterial pathogens causing very different diseases. One of the most intriguing aspects of phospholipases is their potential to interfere with cellular signaling cascades and to modulate the host–immune response. Here, we investigated the role of the innate and acquired immune responses elicited by
Chlamydophila pneumoniae
phospholipase D (CpPLD) in the pathogenesis of atherosclerosis. We evaluated the cytokine and chemokine production induced by CpPLD in healthy donors’ monocytes and in vivo activated T cells specific for CpPLD that infiltrate atherosclerotic lesions of patients with
C. pneumoniae
antibodies. We also examined the helper function of CpPLD-specific T cells for monocyte matrix metalloproteinase (MMP)-9 and tissue factor (TF) production as well as the CpPLD-induced chemokine expression by human venular endothelial cells (HUVECs). We report here that CpPLD is a TLR4 agonist able to induce the expression of IL-23, IL-6, IL-1β, TGF-β, and CCL-20 in monocytes, as well as CXCL-9, CCL-20, CCL-4, CCL-2, ICAM-1, and VCAM-1 in HUVECs. Plaque-derived T cells produce IL-17 in response to CpPLD. Moreover, CpPLD-specific CD4
+
T lymphocytes display helper function for monocyte MMP-9 and TF production. CpPLD promotes Th17 cell migration through the induction of chemokine secretion and adhesion molecule expression on endothelial cells. These findings indicate that CpPLD is able to drive the expression of IL-23, IL-6, IL-1β, TGF-β, and CCL-20 by monocytes and to elicit a Th17 immune response that plays a key role in the genesis of atherosclerosis.
Heterogeneity of hunting ability and nutritional status among domestic dogs in lowland Nicaragua
Authors: Koster Jeremy M. , Tankersley Kenneth B.
Published: January 2012

In past and modern human societies, dogs have played an important role as hunting companions. Given considerable ethnographic evidence that dogs vary in their hunting abilities, this paper addresses the effects of key demographic variables, namely age and sex, on the amount of harvested game that dogs contribute in an indigenous Nicaraguan community. Controlling for variation in the time spent potentially hunting, male dogs and older dogs are significantly associated with greater harvests. These results may account for documented preferences for males in both archaeological and ethnographic contexts. Among societies in which dogs are used both as hunting companions and sources of food, the age-related delay in peak hunting ability also suggests a tradeoff that might explain the consumption of dogs shortly after they have reached adult size. Informant rankings of two cohorts of dogs indicate that residents of the community exhibit high agreement about the relative abilities of the dogs, and the rankings indicate that dogs from the same household exhibit comparable skill. There is little evidence that talented, highly-ranked dogs are provided a more nutritious diet, as measured by nitrogen-based and carbon-based isotopic analysis of hair samples. Overall, although dogs can be quite advantageous as hunting companions, this research suggests that the heterogeneity of hunting ability combines with the high mortality of dogs to impose risks on households that depend on dogs as a source of harvested meat.
Unveiling the biosynthetic puzzle of destruxins in
Metarhizium
species
Authors: Wang Bing , Kang Qianjin , Lu Yuzhen , Bai Linquan , Wang Chengshu
Published: January 2012

Insect pathogenic fungi produce a plethora of insecticidally and pharmaceutically active compounds, including 39 cyclohexadepsipeptide destruxins (dtxs). Even though dtxs were first discovered more than 50 y ago, the genes responsible for their biosynthesis were unknown until this study. Based on our comparative genomic information and targeted gene disruptions, we report the gene cluster for dtx biosynthesis in the insect pathogen
Metarhizium robertsii
. The nonribosomal peptide synthetase DtxS1 has six adenylation domains, two of which are capable of selecting different amino acids to synthesize dtx B and its analogs. The cytochrome P450 enzyme DtxS2 converts dtx B into other dtxs by a chain of reactions, each producing a new derivative. The aldo-keto reductase DtxS3 and aspartic acid decarboxylase DtxS4 are responsible for the conversion and provision of the first and last substrates for the dtx assembly line, respectively. Insect bioassays showed that dtxs could suppress both cellular and humoral immune responses thereby assisting fungal propagation in insects. The differing abilities of
Metarhizium
species to produce toxins is dependent on the presence of the
dtxS1
gene. The toxigenic species are capable of killing multiple orders of insects, whereas the nontoxigenic
Metarhizium
spp. have narrow host ranges. Thus, the acquisition or retention of the dtx biosynthesis gene cluster in
Metarhizium
lineages has been coordinated with the evolution of fungal host specificity. The data from this study will facilitate the development of dtxs as bioinsecticides or pharmaceuticals.
The Dynamics of Goal Revision: A Cybernetic Multiperiod Test-Operate-Test-Adjust-Loop (TOTAL) Model of Self-Regulation
Authors: Wang Chen , Mukhopadhyay Anirban
Published: January 2012

This research presents a comprehensive conceptual model of the dynamics of goal revision over multiple periods. First, based on an integrative literature review, we derive four principles that govern how individuals update their goals over time (monotonicity, diminishing sensitivity, aspiration maximization, and performance satisficing). We then integrate these principles logically as well as mathematically into a goal-discrepancy response function. Next, we advance existing cybernetic models of self-regulation by synthesizing the four principles and the response function into a Test-Operate-Test-Adjust-Loop (TOTAL) model, which captures the dynamics of goal revision in self-regulation. We report four laboratory experiments that demonstrate initial support for the postulates of our model and conclude with a discussion of limitations and future directions.
Influence via Comparison-Driven Self-Evaluation and Restoration: The Case of the Low-Status Influencer
Authors: Shalev Edith , Morwitz Vicki G.
Published: January 2012

Ample research shows that consumers accept influence from a source they identify with and reject influence from a source they wish to dissociate from. The current article moves beyond the well-established identification principle and delineates a new influence process. Influence via comparison-driven self-evaluation and restoration (CDSER) takes place when one observes a counterstereotypical product user and, as a result, questions one’s relative standing on the trait that the product symbolizes. In response to this threatening self-evaluation, the observer becomes more interested in the target product. To clearly distinguish CDSER from identification influence, the current investigation focuses on product users with a low socioeconomic status (SES). In contrast to the predictions of the identification principle, this article demonstrates that low-SES users can in some circumstances positively influence observers and increase their purchase intentions. The “low-status user effect” and the CDSER mechanism are demonstrated across multiple product categories in four studies.
The Arabidopsis TETRATRICOPEPTIDE THIOREDOXIN-LIKE Gene Family Is Required for Osmotic Stress Tolerance and Male Sporogenesis
Authors: Lakhssassi Naoufal , Doblas Verónica G. , Rosado Abel , del Valle Alicia Esteban , Posé David , Jimenez Antonio J. , Castillo Araceli G. , Valpuesta Victoriano , Borsani Omar , Botella Miguel A.
Published: January 2012

TETRATRICOPEPTIDE THIOREDOXIN-LIKE (TTL) proteins are characterized by the presence of six tetratricopeptide repeats in conserved positions and a carboxyl-terminal region known as the thioredoxin-like domain with homology to thioredoxins. In Arabidopsis (Arabidopsis thaliana), the TTL gene family is composed by four members, and the founder member, TTL1, is required for osmotic stress tolerance. Analysis of sequenced genomes indicates that TTL genes are specific to land plants. In this study, we report the expression profiles of Arabidopsis TTL genes using data mining and promoter-reporter β-glucuronidase fusions. Our results show that TTL1, TTL3, and TTL4 display ubiquitous expression in normal growing conditions but differential expression patterns in response to osmotic and NaCl stresses. TTL2 shows a very different expression pattern, being specific to pollen grains. Consistent with the expression data, ttl1, ttl3, and ttl4 mutants show reduced root growth under osmotic stress, and the analysis of double and triple mutants indicates that TTL1, TTL3, and TTL4 have partially overlapping yet specific functions in abiotic stress tolerance while TTL2 is involved in male gametophytic transmission.
Effects of the 755‐nm Alexandrite laser on fine dark facial hair: Review of 90 cases
Authors: UYAR Belkiz , SAKLAMAZ Ali
Published: January 2012

Laser hair removal is a relatively effective method for thick hair. Despite the risk for induction of fine hair growth, application of laser for fine dark hair is sometimes inevitable. We investigate the effects of 755‐nm Alexandrite laser on fine dark facial hair and evaluate the induction rates of fine hair growth and case satisfaction. In the present study, the thickening rate of hairs (33.33%) was found to be higher than the previously published rates. However, reduction of hair density can be obtained when the laser sessions are continued.
Mechanical stretch inhibits adipogenesis and stimulates osteogenesis of adipose stem cells
Authors: Yang X. , Cai X. , Wang J. , Tang H. , Yuan Q. , Gong P. , Lin Y.
Published: January 2012

A reciprocal relationships between osteogenesis and adipogenesis has been observed in vitro and in vivo, and mechanical stretch has been believed to be a regulating factor of osteo‐adipogenic axis differentiation of mesenchymal stem cells. In this study, rat adipose stem cells (ASCs) were isolated and cultured in adipogenic or normal medium. Their exposure to cyclic mechanical stretch (2000 με, 1 Hz) in the presence of adipogenic medium decreased mRNA and protein level of PPAR‐γ, and increased Runx2 mRNA and protein levels as well as Pref‐1 mRNA level, compared to static samples. ASCs cultured in normal medium without adipogenic induction did not show any significant change in mRNA expression of PPAR‐γ, Runx2, nor Pref‐1 irrespective of mechanical loading. Stretching induced phosphorylation of extracellular signal‐regulated protein kinases 1 and 2 (ERK1/2) during the induction period. It was concluded that mechanical stretch inhibited adipogenesis and stimulated osteogenesis of these ASCs in the presence of adipogenic medium and that ERK1/2 activation may be involved in the mechanical stress‐induced trans‐differentiation.
An unusual feature associated with LEE1 P1 promoters in enteropathogenic Escherichia coli (EPEC)
Authors: Jeong Jae‐Ho , Kim Hyun‐Ju , Kim Kun‐Hee , Shin Minsang , Hong Yeongjin , Rhee Joon Haeng , Schneider Thomas D. , Choy Hyon E.
Published: January 2012

Transcription start points in bacteria are influenced by the nature of the RNA polymerase·promoter interaction. For Escherichia coli RNA polymerase holoenzyme containing σ70, it is presumed that specific sequence in one or more of the −10, extended −10 and −35 elements of the promoter guides the RNAP to select the cognate start point. Here, we investigated the promoter driving expression of the LEE1 operon in enteropathogenic E. coli and found two promoters separated by 10 bp, LEE1 P1A (+1) and LEE1 P1B (+10) using various in vitro biochemical tools. A unique feature of P1B was the presence of multiple transcription starts from five neighbouring As at the initial transcribed region. The multiple products did not arise from stuttering synthesis. Analytical software based on information theory was employed to determine promoter elements. The concentration of the NTP pool altered the preferred transcription start points, albeit the underlying mechanism is elusive. Under in vivo conditions, dominant P1B, but not P1A, was subject to regulation by IHF.
Separate structural and functional domains of Tn4430 transposase contribute to target immunity
Authors: Lambin Michaël , Nicolas Emilien , Oger Cédric A. , Nguyen Nathan , Prozzi Deborah , Hallet Bernard
Published: January 2012

Like other transposons of the Tn3 family, Tn4430 exhibits target immunity, a process that prevents multiple insertions of the transposon into the same DNA molecule. Immunity is conferred by the terminal inverted repeats of the transposon and is specific to each element of the family, indicating that the transposase TnpA is directly involved in the process. However, the molecular mechanism whereby this protein promotes efficient transposition into permissive targets while preventing transposition into immune targets remains unknown. Here, we demonstrate that both functions of TnpA can be uncoupled from each other by isolating and characterizing mutants that are proficient in transposition (T+) but impaired in immunity (I‐). The identified T+/I‐ mutations are clustered into separate structural and functional domains of TnpA, indicating that different activities of the protein contribute to immunity. Combination of separate mutations had synergistic effects on target immunity but contrasting effects on transposition. One class of mutations was found to stimulate transposition, whereas other mutations appeared to reduce TnpA activity. The data are discussed with respect to alternative models in which TnpA acts as a specific determinant to both establish and respond to immunity.
DivIVA affects secretion of virulence‐related autolysins in Listeria monocytogenes
Authors: Halbedel Sven , Hahn Birgit , Daniel Richard A. , Flieger Antje
Published: January 2012

DivIVA is a well‐conserved coiled‐coil protein present in most Gram‐positive bacteria and has been implicated in division site selection, peptidoglycan biosynthesis and sporulation. DivIVA proteins bind lipid membranes and characteristically accumulate at curved membrane areas, i.e. the cell poles and the division site, to which they recruit various interaction partners. We have studied the role of this morphogen in the human pathogen Listeria monocytogenes and our results suggest a novel mechanism by which DivIVA contributes to cell division. Contrary to expectation a ΔdivIVA mutant exhibited a pronounced chaining phenotype rather than a defect in cell division which we attributed to reduced extracellular levels of the autolytic enzymes p60 and MurA. We demonstrate that this is due to a malfunction in secretion of these autolysins and phenotypic comparison of the ΔdivIVA strain with a ΔsecA2 mutant suggests that DivIVA influences the activity of the SecA2 secretion route in L. monocytogenes. Also from the phenotypic analysis it was clear that divIVA affected swarming motility, biofilm formation, invasiveness and cell‐to‐cell spread in cell culture infection models. Thus, our experiments show that DivIVA is an important factor for various listerial traits that are essential for the pathogenicity of this organism.
Characterization of the Group A Streptococcus Mga virulence regulator reveals a role for the C‐terminal region in oligomerization and transcriptional activation
Authors: Hondorp Elise R. , Hou Sherry C. , Hempstead Andrew D. , Hause Lara L. , Beckett Dorothy M. , McIver Kevin S.
Published: January 2012

The Group A Streptococcus (GAS) is a strict human pathogen that causes a broad spectrum of illnesses. One of the key regulators of virulence in GAS is the transcriptional activator Mga, which co‐ordinates the early stages of infection. Although the targets of Mga have been well characterized, basic biochemical analyses have been limited due to difficulties in obtaining purified protein. In this study, high‐level purification of soluble Mga was achieved, enabling the first detailed characterization of the protein. Fluorescence titrations coupled with filter‐binding assays indicate that Mga binds cognate DNA with nanomolar affinity. Gel filtration analyses, analytical ultracentrifugation and co‐immunoprecipitation experiments demonstrate that Mga forms oligomers in solution. Moreover, the ability of the protein to oligomerize in solution was found to correlate with transcriptional activation; DNA binding appears to be necessary but insufficient for full activity. Truncation analyses reveal that the uncharacterized C‐terminal region of Mga, possessing similarity to phosphotransferase system EIIB proteins, plays a critical role in oligomerization and in vivo activity. Mga from a divergent serotype was found to behave similarly, suggesting that this study describes a general mechanism for Mga regulation of target virulence genes within GAS and provides insight into related regulators in other Gram‐positive pathogens.
Influence of temperature on infection and establishment of ‘Candidatus Liberibacter americanus’ and ‘Candidatus Liberibacter asiaticus’ in citrus plants
Authors: Gasparoto M. C. G. , Coletta‐Filho H. D. , Bassanezi R. B. , Lopes S. A. , Lourenço S. A. , Amorim L.
Published: January 2012

The objectives of this work were (i) to determine the influence of temperature on infection of citrus by ‘Candidatus Liberibacter asiaticus’ and ‘Candidatus Liberibacter americanus’, the two bacterial species associated with citrus huanglongbing (HLB) in Brazil, and (ii) to determine the influence of temperature on citrus colonization by ‘Ca. L. asiaticus’, which has taken over from ‘Ca. L. americanus’ as the predominant species in Brazil since 2008. Two experiments were carried out with graft‐inoculated Valencia oranges on Rangpur lime rootstocks. Immediately after inoculation the plants were maintained for 423 days in growth chambers under the following night/day temperature conditions: 17/22, 22/27 or 27/32°C, with a dark/light photoperiod of 8/16 h. Infection and colonization of plants were determined using quantitative PCR (qPCR). ‘Candidatus Liberibacter americanus’ did not infect the plants maintained at 27/32°C; however, infection by ‘Ca. L. asiaticus’ occurred at all studied temperatures. Two months after inoculation, ‘Ca. L. asiaticus’ was distributed throughout the inoculated plants, with mean Ct values in the range of 30–31 for leaves and 25–28 for roots. Over time, ‘Ca. L. asiaticus’ reached the highest titres in mature leaves (mean Ct value = 26·7) of citrus plants maintained at 22/27°C. ‘Candidatus Liberibacter asiaticus’ colonization of citrus plants was negatively affected by the daily temperature regime of 27/32°C (mean Ct value in mature leaves = 33·6).
Complement Activation and Interleukin Response in Major Abdominal Surgery
Authors: Kvarnström A. L. , Sarbinowski R. T. , Bengtson J.‐P. , Jacobsson L. M. , Bengtsson A. L.
Published: January 2012

The objective of this study was to evaluate whether major abdominal surgery leads to complement activation and interleukin response and whether the kind of anaesthesia influence complement activation and the release of inflammatory interleukins. The study design was prospective and randomised. Fifty patients undergoing open major colorectal surgery due to cancer disease or inflammatory bowel disease were studied. Twenty‐five patients were given total intravenous anaesthesia (TIVA) with propofol and remifentanil, and 25 patients were given inhalational anaesthesia with sevoflurane and fentanyl. To determine complement activation (C3a and SC5b‐9) and the release of pro‐ and anti‐inflammatory interleukins (tumour necrosis factor‐a (TNF‐a)), interleukin‐1b (IL‐1b), IL‐6, IL‐8, IL‐4 and IL‐10), blood samples were drawn preoperatively, 60 minutes after start of surgery, 30 minutes after end of surgery and 24 hours postoperatively. Complement was activated and pro‐inflammatory interleukins (IL‐6 and IL‐8) and anti‐inflammatory interleukins (IL‐10) were released during major colorectal surgery. There was no significant difference between TIVA and inhalational anaesthesia regarding complement activation and cytokine release. Major colorectal surgery leads to activation of the complement cascade and the release of both pro‐inflammatory and anti‐inflammatory cytokines. There are no significant differences between total intravenous anaesthesia (TIVA) with propofol and remifentanil and inhalational anaesthesia with sevoflurane and fentanyl regarding complement activation and the release of pro‐ and anti‐inflammatory interleukins.
A Novel Mutation W388X Underlying Properdin Deficiency in a Finnish Family
Authors: Helminen M. , Seitsonen S. , Jarva H. , Meri S. , Järvelä I. E.
Published: January 2012

Properdin deficiency is a rare immunological disorder inherited as an X‐chromosomal recessive trait. Properdin deficiency poses a significant risk for severe meningococcal infections. About 20 mutations have been reported to underlie properdin deficiency. Here we report a large Finnish family with a novel mutation in the properdin gene (CFP). Based on the total absence of properdin activity in a 14‐year‐old male patient with an infection resembling meningococcal bacteraemia, the coding region and splice sites of the gene were sequenced. The mutation is located in exon 9 and changes guanine to adenine at nucleotide 1164 (c.1164G>A) that causes tryptophan to change to a premature stop codon (W388X). The mother of the patient was shown to be a carrier of the mutation. In total, the mutation was identified in six females and three young males in the family. The mutation must be inherited from the grandfather who had died of an unknown infectious disease. This is the first mutation of the properdin gene identified in Finland.
Risk and Prognosis of Campylobacteriosis in Relation to Polymorphisms of Host Inflammatory Cytokine Genes
Authors: Nielsen H. , Steffensen R. , Ejlertsen T.
Published: January 2012

The risk of infection with Campylobacter jejuni/coli as well as complications may be related to host genetics. We assessed six single‐nucleotide polymorphisms in inflammatory cytokine genes in 105 patients with Campylobacter jejuni/coli gastroenteritis. The population distribution of the genes was determined in healthy subjects. The patients responded to mailed questionnaires with regard to reactive arthritis (RA) and irritable bowel syndrome (IBS) in 6‐month follow‐up. The genotype INFG(+ 874A/A) was less frequent in patients than in controls (20% versus 33%; P = 0.015), whereas the distribution of the other five SNPs did not differ from controls. After 6 months, RA had developed in 15 subjects and IBS in 20 subjects. RA was significant more frequent in patients with IL‐18(‐137G/G) (22%) than IL‐18(‐137C/C) (0%), P = 0.03, with INFG(+874 T/T (32%) than INFG(+874A/A) (0%), P = 0.007, and with INFG(+2197 A/A) (22%) than INFG(+2197G/G) (0%), P = 0.02. The development of IBS was not linked to gene polymorphisms. In conclusion, the risk of acquiring clinical gastroenteritis with Campylobacter jejuni/coli is related to the INFG (+ 874A>T) of intron 1. Polymorphisms in IL‐18 and INFG are linked to the risk of post‐infectious reactive arthritis, but not to irritable bowel syndrome.
Cycles of humid‐dry climate conditions around the P/E boundary: new stable isotope data from terrestrial organic matter in Vasterival section (NW France)
Authors: Storme Jean‐Yves , Dupuis Christian , Schnyder Johann , Quesnel Florence , Garel Sylvain , Iakovleva Alina I. , Iacumin Paola , Di Matteo Antonietta , Sebilo Mathieu , Yans Johan
Published: January 2012

Terra Nova, 24, 114–122, 2012

The Palaeocene/Eocene boundary (P/EB) and the Palaeocene–Eocene Thermal Maximum (55.8 Ma) are defined stratigraphically based on carbon isotope ratios of various materials. Here, the position of the P/EB is refined in the terrestrial–lacustrine and swampy Vasterival section (Upper Normandy coast, France) by using carbon isotopes measured on dispersed organic matter (δ13Corg). Moreover, nitrogen isotopes on dispersed organic matter (δ15Norg) are, for the first time in the Palaeogene record, associated with carbon isotope and lithological data to constrain palaeoclimatic and environmental changes around the P/EB in a terrestrial environment. Humid‐dry fluctuations before and during this key interval in Earth history are suggested.
Stable integration of an engineered megabase repeat array into the maize genome
Authors: Zhang Han , Phan Bao H. , Wang Kai , Artelt Barbara J. , Jiang Jiming , Parrott Wayne A. , Dawe R. Kelly
Published: January 2012

Plant genome engineering as a practical matter will require stable introduction of long and complex segments of DNA sequence into plant genomes. Here we show that it is possible to synthetically engineer and introduce centromere‐sized satellite repeat arrays into maize. We designed a synthetic repeat monomer of 156 bp that contains five DNA‐binding motifs (LacO, TetO, Gal4, LexA, and CENPB), and extended it into tandem arrays using an overlapping PCR method similar to that commonly used in gene synthesis. The PCR products were then directly transformed into maize using biolistic transformation. We identified three resulting insertion sites (arrayed binding sites), the longest of which is at least 1100 kb. The LacI DNA‐binding module is sufficient to efficiently tether YFP to the arrayed binding sites. We conclude that synthetic repeats can be delivered into plant cells by omitting passage through Escherichia coli, that they generally insert into one locus, and that great lengths may be achieved. It is anticipated that these experimental approaches will be useful for future applications in artificial chromosome design.