bluuebunny/crossref_metadata_2025 huggingface dataset:
Electric-field control of domain wall nucleation and pinning in a metallic ferromagnet
Authors: Bernand-Mantel A. , Herrera-Diez L. , Ranno L. , Pizzini S. , Vogel J. , Givord D. , Auffret S. , Boulle O. , Miron I. M. , Gaudin G.
Published: March 2013

The electric (E)-field control of magnetic properties opens the prospects of an alternative to magnetic field or electric current activation to control magnetization. Multilayers with perpendicular magnetic anisotropy have proven to be particularly sensitive to the influence of an E-field due to the interfacial origin of their anisotropy. In these systems, E-field effects have been recently applied to assist magnetization switching and control domain wall (DW) velocity. Here we report on two new applications of the E-field in a similar material: controlling domain wall nucleation and stopping DW propagation at the edge of the electrode.
Ultra high open circuit voltage (>1 V) of poly-3-hexylthiophene based organic solar cells with concentrated light
Authors: Tromholt Thomas , Madsen Morten V. , Krebs Frederik C.
Published: March 2013

One approach to increasing polymer solar cell efficiency is to blend poly-(3-hexyl-thiophene) with poorly electron accepting fullerene derivatives to obtain higher open circuit voltage (Voc). In this letter concentrated light is used to study the electrical properties of cell operation at up to 2000 solar intensities of these photoactive blends. Comparison of solar cells based on five different fullerene derivatives shows that at both short circuit and open circuit conditions, recombination remains unchanged up to 50 suns. Determination of Voc at 2000 suns demonstrated that the same logarithmic Voc evolution is observed from 0.4 to 2000 suns, where a maximum Voc of 1019 mV was obtained.
Plasmon-assisted high reflectivity and strong magneto-optical Kerr effect in permalloy gratings
Authors: Kostylev Nikita , Maksymov Ivan S. , Adeyeye Adekunle O. , Samarin Sergey , Kostylev Mikhail , Williams Jim F.
Published: March 2013

We demonstrate experimentally a strong plasmon-assisted enhancement of the transverse magneto-optical Kerr effect in permalloy gratings. The enhanced transverse magneto-optical Kerr effect is accompanied by an increased grating reflectivity with the maximum of enhancement being correlated with plasmonic Fano resonances. This correlation was confirmed by an intuitive Fano model and also through full-vectorial optical simulations. Simultaneously high reflectivity and transverse magneto-optical Kerr effect as well as narrowest ferromagnetic resonance linewidth and vanishing anisotropy make permalloy nanostructures attractive for applications in spintronics and nano-optics such as, for example, all-optical excitation of propagating spin waves and spectral tuning of optical nanoantennas.
The location and doping effect of boron in Si nanocrystals embedded silicon oxide film
Authors: Xie Min , Li Dongsheng , Chen Le , Wang Feng , Zhu Xiaodong , Yang Deren
Published: March 2013

Electrically activated doping of boron (B) atoms into the Si-nanocrystals (Si-NCs) embedded silicon oxide film is achieved by co-sputtering technique following with the annealing treatment. The evolution of the size, the shape, and the density of Si-NCs with the doping of B atoms is investigated. The observation of x-ray photoelectron spectroscopy of Si 2p and B 1s and the decrease in lattice spacing of Si (111) plane suggest that B atoms are doped into Si-NCs. The activated doping is confirmed by the Fano effect of the micro-Raman spectra for Si-NCs and the drastic decrease of the sheet resistance.
High optical gain of I–VII semiconductor quantum wells for efficient light-emitting devices
Authors: Ahn Doyeol , Lien Chuang Shun
Published: March 2013

In this work, we propose I–VII semiconductor hetero-structure quantum wells as active layers, which have a large exciton binding energy suitable for strong optical transitions in light-emitting devices. They are also closely lattice-matched to Si substrates, therefore free from defects. A multiband effective mass approach and non-Markovian model including the excitonic effects are used to study the optical gain. It is found that the optical gain of our design would be much higher than that of III–V nitride layers due to the inherent strong excitonic effects and negligible electrostatic fields within the active layers leading to highly efficient optical devices.
Vector magneto-optical generalized ellipsometry for sculptured thin films
Authors: Schmidt Daniel , Briley Chad , Schubert Eva , Schubert Mathias
Published: March 2013

Vector magneto-optical generalized ellipsometry is employed for the determination of the three-dimensional magnetization properties of magnetized thin solid as well as slanted columnar thin film samples. The permalloy thin films were probed by means of Mueller matrix ellipsometry at room-temperature while an external magnetic field was rotated step-wise within each plane of a three-dimensional Cartesian coordinate system (spatial hysteresis loops). Model analysis of the magneto-optical coupling parameter (proportional to the magnetization) confirms the expected uniaxial magnetization shape of the thin solid film and reveals the three-dimensional magneto-optic anisotropy of the nanostructured thin film.
Preferences for Facial and Vocal Masculinity in Homosexual Men: The Role of Relationship Status, Sexual Restrictiveness, and Self-Perceived Masculinity
Authors: Valentová Jaroslava , Roberts S Craig , Havlíček Jan
Published: March 2013

Studies on mate preferences usually examine heterosexual attraction; comparatively little is known about preferences of individuals whose sexuality is aimed at the same sex. We examined preferences of two groups of androphilic individuals—homosexual men and heterosexual women—for male facial and vocal level of masculinity. Facial images of 58 men and vocal recordings of 30 men were rated by 51 heterosexual women and 33 homosexual men for their attractiveness and masculinity-femininity. In both groups of raters, ratings of vocal attractiveness and masculinity were positively correlated, but there was no overall preference for facial masculinity. After splitting raters according to their relationship status, sexual restrictiveness, and self-rated masculinity, we found significant preferences for masculine voices only in single homosexual men and coupled heterosexual women, while a preference for feminine male faces was found in coupled homosexual men. Furthermore, homosexual men describing themselves as relatively masculine significantly preferred masculine voices but also more feminine male faces. Our results demonstrate that conditional mate preferences are not restricted to heterosexual interactions, and homosexual men prefer a mixture of masculine and feminine traits in their potential male partners.
Viewpoint and Pose in Body-Form Adaptation
Authors: Sekunova Alla , Black Michael , Parkinson Laura , Barton Jason J S
Published: March 2013

Faces and bodies are complex structures, perception of which can play important roles in person identification and inference of emotional state. Face representations have been explored using behavioural adaptation: in particular, studies have shown that face aftereffects show relatively broad tuning for viewpoint, consistent with origin in a high-level structural descriptor far removed from the retinal image. Our goals were to determine first, if body aftereffects also showed a degree of viewpoint invariance, and second if they also showed pose invariance, given that changes in pose create even more dramatic changes in the 2-D retinal image. We used a 3-D model of the human body to generate headless body images, whose parameters could be varied to generate different body forms, viewpoints, and poses. In the first experiment, subjects adapted to varying viewpoints of either slim or heavy bodies in a neutral stance, followed by test stimuli that were all front-facing. In the second experiment, we used the same front-facing bodies in neutral stance as test stimuli, but compared adaptation from bodies in the same neutral stance to adaptation with the same bodies in different poses. We found that body aftereffects were obtained over substantial viewpoint changes, with no significant decline in aftereffect magnitude with increasing viewpoint difference between adapting and test images. Aftereffects also showed transfer across one change in pose but not across another. We conclude that body representations may have more viewpoint invariance than faces, and demonstrate at least some transfer across pose, consistent with a high-level structural description.
Response Bias Cannot Explain Action-Specific Effects: Evidence from Compliant and Non-Compliant Participants
Authors: Witt Jessica K , Sugovic Mila
Published: March 2013

According to the action-specific account of perception, the perceiver's ability to act influences perception of the target. For example, targets that are easier to acquire are reported to look closer, bigger, and slower. However, an alternative explanation for these effects is that they are due to response bias, rather than to changes in perception. To test the role of response bias, we employed two separate manipulations. We manipulated people's abilities to block a ball and measured the corresponding effects on estimated ball speed. We also created an explicit task demand by giving participants instructions that emphasized responding either slow or fast. Participants were grouped, based on whether they were compliant or non-compliant with the instructions. Regardless of their compliance, we found an action-specific effect of blocking ability on estimated speed. Given that non-compliant participants still showed the effect, the results provide strong evidence against a response-bias explanation of this action-specific effect. Paired with earlier research, we conclude that blocking ability influences perceived speed. Perception expresses the relationship between the environment and the perceiver, and this view is consistent with emerging neural and behavioral evidence for an interconnected perceptual–motor system.
On Depth Processing in the Production of the Ponzo Illusion: Two Problems and a Solution
Authors: Parks Theodore E
Published: March 2013

Certain phenomenological difficulties for the depth-processing/size-scaling theory of the Ponzo illusion can be resolved if those theoretical activities are carried out in Milner and Goodale's proposed vision-for-action cortical pathway.
Eyespots in a Reversible Setting
Authors: Deręgowski Jan B , Gray Colin D
Published: March 2013

When eyespots were presented on a reversible figure, the total duration for which elements bearing the eyespots were seen as closer to the observer was found to be greater than the total for counterpart elements. It is speculated that the tendency to see eyespots as nearer than they really are is related to the manner in which they are responded to in nature.
Fox baiting in agricultural landscapes: preliminary findings on the importance of bait-site selection
Authors: Carter Andrew , Luck Gary W.
Published: March 2013

Context Little is known about the importance of bait-site selection during lethal fox-baiting programmes. Improved bait placement may increase the efficacy of baiting and help reduce fox impacts on wildlife and livestock. Aims To determine whether bait uptake by the red fox (Vulpes vulpes) differed among five landscape elements (roadsides, fence lines, open paddocks, creek lines and remnant vegetation) and at sites with high or low habitat (ground cover) complexity. Methods We measured bait uptake at 300 bait stations distributed evenly among the landscape elements in agricultural landscapes in northern Victoria, Australia. Bait uptake was also compared between sites with low and high habitat complexity in districts subject to no fox control and annual fox control. Key results Among landscape elements, bait uptake was significantly higher in roadside vegetation and along vegetated creek lines than it was along fence lines and in open paddocks (P < 0.05 in each case). Within roadside vegetation, bait uptake was significantly (P = 0.001) lower at sites with a high habitat complexity than at sites with low complexity, particularly in areas subject to annual fox control. Conclusions Bait placement influences bait-uptake rates considerably and greater consideration should be placed on bait-site selection during fox-baiting programmes. Habitat complexity limited bait uptake, which may indicate a reduced capacity of foxes to find baits in complex habitats. Implications Our results should help improve bait-site selection in agricultural landscapes and may increase the efficacy of fox baiting to the benefit of native fauna and livestock.
Fly cryptochrome and the visual system
Authors: Mazzotta Gabriella , Rossi Alessandro , Leonardi Emanuela , Mason Moyra , Bertolucci Cristiano , Caccin Laura , Spolaore Barbara , Martin Alberto J. M. , Schlichting Matthias , Grebler Rudi , Helfrich-Förster Charlotte , Mammi Stefano , Costa Rodolfo , Tosatto Silvio C. E.
Published: March 2013

Cryptochromes are flavoproteins, structurally and evolutionarily related to photolyases, that are involved in the development, magnetoreception, and temporal organization of a variety of organisms.
Drosophila
CRYPTOCHROME (dCRY) is involved in light synchronization of the master circadian clock, and its C terminus plays an important role in modulating light sensitivity and activity of the protein. The activation of dCRY by light requires a conformational change, but it has been suggested that activation could be mediated also by specific “regulators” that bind the C terminus of the protein. This C-terminal region harbors several protein–protein interaction motifs, likely relevant for signal transduction regulation. Here, we show that some functional linear motifs are evolutionarily conserved in the C terminus of cryptochromes and that class III PDZ-binding sites are selectively maintained in animals. A coimmunoprecipitation assay followed by mass spectrometry analysis revealed that dCRY interacts with Retinal Degeneration A (RDGA) and with Neither Inactivation Nor Afterpotential C (NINAC) proteins. Both proteins belong to a multiprotein complex (the Signalplex) that includes visual-signaling molecules. Using bioinformatic and molecular approaches, dCRY was found to interact with Neither Inactivation Nor Afterpotential C through Inactivation No Afterpotential D (INAD) in a light-dependent manner and that the CRY–Inactivation No Afterpotential D interaction is mediated by specific domains of the two proteins and involves the CRY C terminus. Moreover, an impairment of the visual behavior was observed in fly mutants for dCRY, indicative of a role, direct or indirect, for this photoreceptor in fly vision.
A phase transition in the first passage of a Brownian process through a fluctuating boundary with implications for neural coding
Authors: Taillefumier Thibaud , Magnasco Marcelo O.
Published: March 2013

Finding the first time a fluctuating quantity reaches a given boundary is a deceptively simple-looking problem of vast practical importance in physics, biology, chemistry, neuroscience, economics, and industrial engineering. Problems in which the bound to be traversed is itself a fluctuating function of time include widely studied problems in neural coding, such as neuronal integrators with irregular inputs and internal noise. We show that the probability
p
(
t
) that a Gauss–Markov process will first exceed the boundary at time
t
suffers a phase transition as a function of the roughness of the boundary, as measured by its Hölder exponent
H
. The critical value occurs when the roughness of the boundary equals the roughness of the process, so for diffusive processes the critical value is
H

c

= 1/2. For smoother boundaries,
H
> 1/2, the probability density is a continuous function of time. For rougher boundaries,
H
< 1/2, the probability is concentrated on a Cantor-like set of zero measure: the probability density becomes divergent, almost everywhere either zero or infinity. The critical point
H

c

= 1/2 corresponds to a widely studied case in the theory of neural coding, in which the external input integrated by a model neuron is a white-noise process, as in the case of uncorrelated but precisely balanced excitatory and inhibitory inputs. We argue that this transition corresponds to a sharp boundary between rate codes, in which the neural firing probability varies smoothly, and temporal codes, in which the neuron fires at sharply defined times regardless of the intensity of internal noise.
Development and validation of a 32-gene prognostic index for prostate cancer progression
Authors: Wu Chin-Lee , Schroeder Brock E. , Ma Xiao-Jun , Cutie Christopher J. , Wu Shulin , Salunga Ranelle , Zhang Yi , Kattan Michael W. , Schnabel Catherine A. , Erlander Mark G. , McDougal W. Scott
Published: March 2013

The accurate determination of the risk of cancer recurrence is an important unmet need in the management of prostate cancer. Patients and physicians must weigh the benefits of currently available therapies against the potential morbidity of these treatments. Herein we describe the development of a gene expression-based continuous risk index and a validation of this test in an independent, blinded cohort of post-radical prostatectomy (RP) patients. A gene expression signature, prognostic for prostate-specific antigen (PSA) recurrence, was identified through a bioinformatic analysis of the expression of 1,536 genes in malignant prostate tissue from a training cohort of consecutive patients treated with RP. The assay was transferred to a real-time RT-PCR platform, and a continuous risk index model was constructed based on the expression of 32 genes. This 32-gene risk index model was validated in an independent, blinded cohort of 270 RP patients. In multivariate analyses, the risk index was prognostic for risk of PSA recurrence and had added value over standard prognostic markers such as Gleason score, pathologic tumor stage, surgical margin status, and presurgery PSA (hazard ratio, 4.05; 95% confidence interval, 1.50–10.94;P= 0.0057). Furthermore, RP patients could be stratified based on the risk of PSA recurrence and the development of metastatic disease. The 32-gene signature identified here is a robust prognostic marker for disease recurrence. This assay may aid in postoperative treatment selection and has the potential to impact decision making at the biopsy stage.
Paradoxical activation and RAF inhibitor resistance of BRAF protein kinase fusions characterizing pediatric astrocytomas
Authors: Sievert Angela J. , Lang Shih-Shan , Boucher Katie L. , Madsen Peter J. , Slaunwhite Erin , Choudhari Namrata , Kellet Meghan , Storm Phillip B. , Resnick Adam C.
Published: March 2013

Astrocytomas are the most common type of brain tumors in children. Activated BRAF protein kinase mutations are characteristic of pediatric astrocytomas with KIAA1549-BRAF fusion genes typifying low-grade astrocytomas and
V600E
BRAF alterations characterizing distinct or higher-grade tumors. Recently, BRAF-targeted therapies, such as vemurafenib, have shown great promise in treating V600E-dependent melanomas. Like
V600E
BRAF, BRAF fusion kinases activate MAPK signaling and are sufficient for malignant transformation; however, here we characterized the distinct mechanisms of action of KIAA1549-BRAF and its differential responsiveness to PLX4720, a first-generation BRAF inhibitor and research analog of vemurafenib. We found that in cells expressing KIAA1549-BRAF, the fusion kinase functions as a homodimer that is resistant to PLX4720 and accordingly is associated with CRAF-independent paradoxical activation of MAPK signaling. Mutagenesis studies demonstrated that KIAA1549-BRAF fusion-mediated signaling is diminished with disruption of the BRAF kinase dimer interface. In addition, the KIAA1549-BRAF fusion displays increased binding affinity to kinase suppressor of RAS (KSR), an RAF relative recently demonstrated to facilitate MEK phosphorylation by BRAF. Despite its resistance to PLX4720, the KIAA1549-BRAF fusion is responsive to a second-generation selective BRAF inhibitor that, unlike vemurafenib, does not induce activation of wild-type BRAF. Our data support the development of targeted treatment paradigms for BRAF-altered pediatric astrocytomas and also demonstrate that therapies must be tailored to the specific mutational context and distinct mechanisms of action of the mutant kinase.
Eosinophil adoptive transfer system to directly evaluate pulmonary eosinophil trafficking in vivo
Authors: Wen Ting , Besse John A. , Mingler Melissa K. , Fulkerson Patricia C. , Rothenberg Marc E.
Published: March 2013

Most in vivo studies of granulocytes draw conclusions about their trafficking based on examination of their steady-state tissue/blood levels, which result from a combination of tissue homing, survival, and egress, rather than direct examination of cellular trafficking. Herein, we developed a unique cell transfer system involving the adoptive transfer of a genetically labeled, bone-marrow–derived unique granulocyte population (eosinophils) into an elicited inflammatory site, the allergic lung. A dual polychromatic FACS-based biomarker-labeling system based on the IL4-eGFP transgene (4get) or
Cd45.1
allele was used to track i.v. transferred eosinophils into the airway following allergen or T
H
2-associated stimuli in the lung in multiple mouse strains. The system was amenable to reverse tagging of recipients, thus allowing transfer of nonlabeled eosinophils and competitive tracking of multiple populations of eosinophils in vivo. The half-life of eosinophils in the blood was 3 h, and migration to the lung was dependent upon the dosage of transferred eosinophils, sensitive to pertussis toxin pretreatment, peaked at ∼24 h after adoptive transfer, and revealed a greater than 8-d eosinophil half-life in the lung. Eosinophil migration to the lung was dependent upon recipient IL-5 and IL-13 receptor α1 and donor eosinophil C-C chemokine receptor type 3 (CCR3) and interleukin 1 receptor-like 1 (ST2) in vivo. Taken together, this unique eosinophil transfer system provides an unprecedented opportunity to examine airway eosinophil migration without the need for extensive efforts to acquire donor source and time-consuming genetic crossing and has already been used to identify a long eosinophil half-life in the allergic lung and a definite role for ST2 in regulating eosinophil trafficking.
Development and in vivo efficacy of targeted polymeric inflammation-resolving nanoparticles
Authors: Kamaly Nazila , Fredman Gabrielle , Subramanian Manikandan , Gadde Suresh , Pesic Aleksandar , Cheung Louis , Fayad Zahi Adel , Langer Robert , Tabas Ira , Cameron Farokhzad Omid
Published: March 2013

Excessive inflammation and failed resolution of the inflammatory response are underlying components of numerous conditions such as arthritis, cardiovascular disease, and cancer. Hence, therapeutics that dampen inflammation and enhance resolution are of considerable interest. In this study, we demonstrate the proresolving activity of sub–100-nm nanoparticles (NPs) containing the anti-inflammatory peptide Ac2-26, an annexin A1/lipocortin 1-mimetic peptide. These NPs were engineered using biodegradable diblock poly(lactic-
co
-glycolic acid)-
b
-polyethyleneglycol and poly(lactic-
co
-glycolic acid)-
b
-polyethyleneglycol collagen IV–targeted polymers. Using a self-limited zymosan-induced peritonitis model, we show that the Ac2-26 NPs (100 ng per mouse) were significantly more potent than Ac2-26 native peptide at limiting recruitment of polymononuclear neutrophils (56% vs. 30%) and at decreasing the resolution interval up to 4 h. Moreover, systemic administration of collagen IV targeted Ac2-26 NPs (in as low as 1 µg peptide per mouse) was shown to significantly block tissue damage in hind-limb ischemia-reperfusion injury by up to 30% in comparison with controls. Together, these findings demonstrate that Ac2-26 NPs are proresolving in vivo and raise the prospect of their use in chronic inflammatory diseases such as atherosclerosis.
Seasonal and Among‐Stream Variation in Predator Encounter Rates for Fish Prey
Authors: Harvey Bret C. , Nakamoto Rodney J.
Published: March 2013

Recognition that predators have indirect effects on prey populations that may exceed their direct consumptive effects highlights the need for a better understanding of spatiotemporal variation in predator–prey interactions. We used photographic monitoring of tethered Rainbow Trout Oncorhynchus mykiss and Cutthroat Trout O. clarkii to quantify predator encounter rates for fish in four streams of northwestern California during winter–spring and summer. To estimate maximum encounter rates, provide the clearest contrast among streams and seasons, and provide an empirical estimate of a key parameter in an individual‐based model of stream salmonids, we consistently placed fish in shallow microhabitats that lacked cover. Over 14‐d periods, predators captured fish at 66 of the 88 locations where fish were placed. Eight species of birds (including two species of owls) and mammals were documented as capturing fish. Thirty‐six percent of the predator encounters occurred at night. Predator encounter rates varied among streams and between seasons; the best‐fitting model of survival included a stream × season interaction. Encounter rates tended to be higher in larger streams than in smaller streams and higher in winter–spring than in summer. Conversion of predator encounter rates from this study to estimates of predation risk by using published information on capture success yielded values similar to an independent estimate of predation risk obtained from calibration of an individual‐based model of the trout population in one of the study streams. The multiple mechanisms linking predation risk to population dynamics argue for additional effort to identify patterns of spatiotemporal variation in predation risk.
Trophic Niche of Invasive White Perch and Potential Interactions with Representative Reservoir Species
Authors: Feiner Zachary S. , Rice James A. , Aday D. Derek
Published: March 2013

The trophic dynamics of invasive species can yield insights into the mechanisms of invasion success and aid in the prediction of potential impacts on established species. Additionally, the predicted effects of an invader may differ depending on how it integrates into the resident food web and whether its resource use changes throughout the invasion process. We investigated the trophic dynamics of populations of invasive White Perch Morone americana in three large North Carolina reservoirs and evaluated the potential for impacts on members of the resident fish community. Specifically, we used stable isotope and diet analyses to evaluate their trophic niche relative to three representative species in each reservoir chosen for their widespread range, potential overlaps with White Perch, recreational value, and representation of ecological guilds based on habitat and prey sources. The species were a native littoral generalist invertivore (Bluegill Lepomis macrochirus), native littoral piscivore (Largemouth Bass Micropterus salmoides), and stocked pelagic piscivore (Striped Bass Morone saxatilis or Walleye Sander vitreus, depending on their availability). Small (<70 mm TL), medium (120–170 mm TL), and large (>200 mm TL) White Perch occupied different trophic positions, and these positions were generally consistent among reservoirs relative to the representative species. Small and medium White Perch had the largest niche areas and high diet overlap with Bluegill in two of three lakes, whereas large White Perch had moderate diet overlap with Striped Bass, Largemouth Bass, and Walleye. As a species, White Perch occupy a wide trophic niche, which may aid in successfully establishing invasive populations. However, White Perch use resources shared by other members of the fish community, which could lead to negative impacts on these species.
Embodied Grounding of Memory: Toward the Effects of Motor Execution on Memory consolidation
Authors: van Dam Wessel O. , Rueschemeyer Shirley-Ann , Bekkering Harold , Lindemann Oliver
Published: March 2013

Behavioural and neuroscientific research has provided evidence for a strong functional link between the neural motor system and lexical–semantic processing of action-related language. It remains unclear, however, whether the impact of motor actions is restricted to online language comprehension or whether sensorimotor codes are also important in the formation and consolidation of persisting memory representations of the word's referents. The current study now demonstrates that recognition performance for action words is modulated by motor actions performed during the retention interval. Specifically, participants were required to learn words denoting objects that were associated with either a pressing or a twisting action (e.g., piano, screwdriver) and words that were not associated to actions. During a 6–8-minute retention phase, participants performed an intervening task that required the execution of pressing or twisting responses. A subsequent recognition task revealed a better memory for words that denoted objects for which the functional use was congruent with the action performed during the retention interval (e.g., pepper mill–twisting action, doorbell–pressing action) than for words that denoted objects for which the functional use was incongruent. In further experiments, we were able to generalize this effect of selective memory enhancement of words by performing congruent motor actions to an implicit perceptual (Experiment 2) and implicit semantic memory test (Experiment 3). Our findings suggest that a reactivation of motor codes affects the process of memory consolidation and emphasizes therefore the important role of sensorimotor codes in establishing enduring semantic representations.
A short carboxyl-terminal tail is required for single-stranded DNA binding, higher-order structural organization, and stability of the mitochondrial single-stranded annealing protein Mgm101
Authors: Mbantenkhu MacMillan , Wierzbicki Sara , Wang Xiaowen , Guo Shangdong , Wilkens Stephan , Chen Xin Jie
Published: March 2013

Mgm101 is a Rad52-type single-stranded annealing protein (SSAP) required for mitochondrial DNA (mtDNA) repair and maintenance. Structurally, Mgm101 forms large oligomeric rings. Here we determine the function(s) of a 32–amino acid carboxyl-terminal tail (Mgm101238–269) conserved in the Mgm101 family of proteins. Mutagenic analysis shows that Lys-253, Trp-257, Arg-259, and Tyr-268 are essential for mtDNA maintenance. Mutations in Lys-251, Arg-252, Lys-260, and Tyr-266 affect mtDNA stability at 37°C and under oxidative stress. The Y268A mutation severely affects single-stranded DNA (ssDNA) binding without altering the ring structure. Mutations in the Lys-251–Arg-252–Lys-253 positive triad also affect ssDNA binding. Moreover, the C-tail alone is sufficient to mediate ssDNA binding. Finally, we find that the W257A and R259A mutations dramatically affect the conformation and oligomeric state of Mgm101. These structural alterations correlate with protein degradation in vivo. The data thus indicate that the C-tail of Mgm101, likely displayed on the ring surface, is required for ssDNA binding, higher-order structural organization, and protein stability. We speculate that an initial electrostatic and base-stacking interaction with ssDNA could remodel ring organization. This may facilitate the formation of nucleoprotein filaments competent for mtDNA repair. These findings could have broad implications for understanding how SSAPs promote DNA repair and genome maintenance.
Kinesin-1 and mitochondrial motility control by discrimination of structurally equivalent but distinct subdomains in Ran-GTP-binding domains of Ran-binding protein 2
Authors: Patil Hemangi , Cho Kyoung-in , Lee James , Yang Yi , Orry Andrew , Ferreira Paulo A.
Published: March 2013

The pleckstrin homology (PH) domain is a versatile fold that mediates a variety of protein–protein and protein–phosphatidylinositol lipid interactions. The Ran-binding protein 2 (RanBP2) contains four interspersed Ran GTPase-binding domains (RBD

n

= 1–4
) with close structural homology to the PH domain of Bruton's tyrosine kinase. The RBD
2
, kinesin-binding domain (KBD) and RBD
3
comprise a tripartite domain (R
2
KR
3
) of RanBP2 that causes the unfolding, microtubule binding and biphasic activation of kinesin-1, a crucial anterograde motor of mitochondrial motility. However, the interplay between Ran GTPase and R
2
KR
3
of RanBP2 in kinesin-1 activation and mitochondrial motility is elusive. We use structure–function, biochemical, kinetic and cell-based assays with time-lapse live-cell microscopy of over 260 000 mitochondrial-motility-related events to find mutually exclusive subdomains in RBD
2
and RBD
3
towards Ran GTPase binding, kinesin-1 activation and mitochondrial motility regulation. The RBD
2
and RBD
3
exhibit Ran-GTP-independent, subdomain and stereochemical-dependent discrimination on the biphasic kinetics of kinesin-1 activation or regulation of mitochondrial motility. Further, KBD alone and R
2
KR
3
stimulate and suppress, respectively, multiple biophysical parameters of mitochondrial motility. The regulation of the bidirectional transport of mitochondria by either KBD or R
2
KR
3
is highly coordinated, because their kinetic effects are accompanied always by changes in mitochondrial motile events of either transport polarity. These studies uncover novel roles in Ran GTPase-independent subdomains of RBD
2
and RBD
3
, and KBD of RanBP2, that confer antagonizing and multi-modal mechanisms of kinesin-1 activation and regulation of mitochondrial motility. These findings open new venues towards the pharmacological harnessing of cooperative and competitive mechanisms regulating kinesins, RanBP2 or mitochondrial motility in disparate human disorders.
Activation of CCR2+ human proinflammatory monocytes by human herpesvirus-6B chemokine N-terminal peptide
Authors: Clark D. J. , Catusse J. , Stacey A. , Borrow P. , Gompels U. A.
Published: March 2013

Human monocytes expressing CCR2 with CD14 and CD16 can mediate antigen presentation, and promote inflammation, brain infiltration and immunosenescence. Recently identified roles are in human immunodeficiency virus infection, tuberculosis and parasitic disease. Human herpesvirus 6B (HHV-6B) encodes a chemokine, U83B, which is monospecific for CCR2, and is distinct from the related HHV-6A U83A, which activates CCR1, CCR4, CCR5, CCR6 and CCR8 on immune effector cells and dendritic cells. These differences could alter leukocyte-subset recruitment for latent/lytic replication and associated neuroinflammatory pathology. Therefore, cellular interactions between U83A and U83B could help dictate potential tropism differences between these viruses. U83A specificity is maintained in the 38-residue N-terminal spliced-truncated form. Here, we sought to determine the basis for the chemokine receptor specificity differences and identify possible applications. To do this we first analysed variation in a natural host population in sub-Saharan Africa where both viruses are equally prevalent and compared these to global strains. Analyses of U83 N-terminal variation in 112 HHV-6A and HHV-6B infections identified 6/38 U83A or U83B-specific residues. We also identified a unique single U83A-specific substitution in one U83B sequence, ‘U83BA’. Next, the variation effects were tested by deriving N-terminal (NT) 17-mer peptides and assaying activation of ex vivo human leukocytes, the natural host and cellular target. Chemotaxis of CCR2+ leukocytes was potently induced by U83B-NT, but not U83BA-NT or U83A-NT. Analyses of the U83B-NT activated population identified migrated CCR2+, but not CCR5+, leukocytes. The U83BA-NT asparagine-lysine14 substitution disrupted activity, thus defining CCR2 specificity and acting as a main determinant for HHV-6A/B differences in cellular interactions. A flow-cytometry-based shape-change assay was designed, and used to provide further evidence that U83B-NT could activate CCR2+CD14+CD16+ monocytes. This defines a potential antiviral target for HHV-6A/B disease and novel peptide immunomodulator for proinflammatory monocytes.
Rhizobial Infection Is Associated with the Development of Peripheral Vasculature in Nodules ofMedicago truncatula
Authors: Guan Dian , Stacey Nicola , Liu Chengwu , Wen Jiangqi , Mysore Kirankumar S. , Torres-Jerez Ivone , Vernié Tatiana , Tadege Million , Zhou Chuanen , Wang Zeng-yu , Udvardi Michael K. , Oldroyd Giles E.D. , Murray Jeremy D.
Published: March 2013

Nodulation in legumes involves the coordination of epidermal infection by rhizobia with cell divisions in the underlying cortex. During nodulation, rhizobia are entrapped within curled root hairs to form an infection pocket. Transcellular tubes called infection threads then develop from the pocket and become colonized by rhizobia. The infection thread grows toward the developing nodule primordia and rhizobia are taken up into the nodule cells, where they eventually fix nitrogen. The epidermal and cortical developmental programs are synchronized by a yet-to-be-identified signal that is transmitted from the outer to the inner cell layers of the root. Using a new allele of the Medicago truncatula mutant Lumpy Infections, lin-4, which forms normal infection pockets but cannot initiate infection threads, we show that infection thread initiation is required for normal nodule development. lin-4 forms nodules with centrally located vascular bundles similar to that found in lateral roots rather than the peripheral vasculature characteristic of legume nodules. The same phenomenon was observed in M. truncatula plants inoculated with the Sinorhizobium meliloti exoY mutant, and the M. truncatula vapyrin-2 mutant, all cases where infections arrest. Nodules on lin-4 have reduced expression of the nodule meristem marker MtCRE1 and do not express root-tip markers. In addition, these mutant nodules have altered patterns of gene expression for the cytokinin and auxin markers CRE1 and DR5. Our work highlights the coordinating role that bacterial infection exerts on the developing nodule and allows us to draw comparisons with primitive actinorhizal nodules and rhizobia-induced nodules on the nonlegume Parasponia andersonii.
Structure of an atypical FeoB G-domain reveals a putative domain-swapped dimer
Authors: Deshpande Chandrika N. , McGrath Aaron P. , Font Josep , Guilfoyle Amy P. , Maher Megan J. , Jormakka Mika
Published: March 2013

FeoB is a transmembrane protein involved in ferrous iron uptake in prokaryotic organisms. FeoB comprises a cytoplasmic soluble domain termed NFeoB and a C-terminal polytopic transmembrane domain. Recent structures of NFeoB have revealed two structural subdomains: a canonical GTPase domain and a five-helix helical domain. The GTPase domain hydrolyses GTP to GDP through a well characterized mechanism, a process which is required for Fe2+transport. In contrast, the precise role of the helical domain has not yet been fully determined. Here, the structure of the cytoplasmic domain of FeoB fromGallionella capsiferriformansis reported. Unlike recent structures of NFeoB, theG. capsiferriformansNFeoB structure is highly unusual in that it does not contain a helical domain. The crystal structures of both apo and GDP-bound protein forms a domain-swapped dimer.
Rotor unsteady aerodynamics model using an efficient free‐vortex method
Authors: Li Pan , Chen Renliang
Published: March 2013

Purpose

The purpose of this paper is to present and validate an efficient time‐marching free‐vortex method for rotor wake analysis and study the rotor wake dynamics in transient and maneuvering flight conditions.

Design/methodology/approach

The rotor wake is represented by vortex filament elements. The equations governing the convection, strain and viscous diffusion of the vortex elements are derived from incompressible Navier‐Stokes equations based on the viscous splitting algorithm. The initial core size of the blade tip vortices is directly computed by a vortex sheet roll‐up model. Then, a second‐order time‐marching algorithm is developed for solving the governing equations. The algorithm is formulated in explicit form to improve computing efficiency. To avoid the numerical instability, a high order variable artificial dissipative term is directly introduced into the algorithm. Finally, the developed method is applied to examine rotor wake geometries in steady‐state and maneuvering flight conditions. Comparisons between predictions and experimental results are made for rotor wake geometries, induced inflow distributions and rotor transient responses, to help validate the new method.

Findings

The algorithm is found to be numerically stable and efficient. The predicted rotor responses have good agreement with experimental data. The transient behavior of the wake dominates the rotor responses following rapid control inputs in hover. The wake curvature effect induced by rotor pitching or rolling rate significantly changes the rotor off‐axis response.

Research limitations/implications

This method should be further validated using experimental measurements of full‐scale helicopter rotors.

Originality/value

The paper presents a new time‐marching free‐vortex wake method, which is suitable for application in helicopter flight simulation.
Attitude cooperative control of spacecraft formation via output‐feedback
Authors: Lv Yueyong , Hu Qinglei , Ma Guangfu , Zhang Jian
Published: March 2013

Purpose

The purpose of this paper is to propose a decentralized output feedback controller for cooperative attitude regulation of spacecraft formation in absence of angular velocity feedback.

Design/methodology/approach

The nonlinear relative attitude dynamic and kinematic equations represented by relative quaternion and relative angular velocity, respectively, are considered in this paper. The lead filter is employed to synthesize virtual angular velocity signal so that the design of output feedback controller is achieved. Lyapunov method is adopted to prove the stability of closed‐loop system. Considering the external disturbance, the theory of L2‐gain disturbance attenuation is employed to improve the designed controller. Numerical simulations are carried out to verify the controllers proposed.

Findings

It is found that the closed‐loop system can be guaranteed asymptotically stable in absence of external disturbance. When disturbance is considered, as long as the sufficient condition proposed is satisfied, the improved controller can render system uniformly ultimately bounded stable.

Practical implications

The proposed output feedback control scheme can be considered as a fall‐back alternative for the case that the angular velocity sensors fail, or seen as another option for the system without angular velocity sensors at all.

Originality/value

Unlike most classical works in the field of output feedback which focus on centralized scheme and neglect the disturbance, the controller proposed in this paper is able to handle the output feedback control problem of multi‐agent formation in a decentralized fashion, so as to avoid the single failure point of a centralized scheme. Meanwhile, the capability of L2‐gain disturbance attenuation is also achieved simultaneously.
Cluster flight orbit design method for fractionated spacecraft
Authors: Wang Jihe , Nakasuka Shinichi
Published: March 2013

Purpose

The purpose of this paper is to propose an intuitive and effective cluster flight orbit design method for fractionated spacecraft.

Design/methodology/approach

Based on the concept of fractionated spacecraft, orbit design requirements for cluster flight in the case of fractionated spacecraft are proposed, and categorized into three requirements: stabilization requirement, passive safety requirement, and the maximum inter‐satellite distance requirement. These design requirements are then reformulated in terms of relative eccentricity and inclination vectors (E/I vectors) using a relative motion model based on relative orbital elements (ROEs). By using ROEs theory, the cluster flight orbit design issue is modelled as the distribution of relative E/I vectors for each member satellite in the cluster, and solved by combining three different heuristic search methods and one nonlinear programming (NLP) method.

Findings

The simulation results show that the NLP method is valid and efficient in solving the cluster flight orbit design problem and that for some cluster flight scenarios, the heuristic search methods can be adopted to give feasible solutions without the NLP method.

Research limitations/implications

The cluster flight scenario in this paper is limited because the cluster should be in the near‐circular low earth orbit (LEO), and the relative distance between the member satellites should be small enough to satisfy the relative motion linearization assumption.

Practical implications

The cluster flight orbit design method proposed in this paper can be applied by fractionated spacecraft mission designers to propose potential cluster flight orbit solutions.

Originality/value

In this paper, the relative E/I vectors method is adopted to propose an intuitive and effective cluster flight orbit design method for fractionated spacecraft.
Aerodynamic performance of Parastoo UAV
Authors: Eslami Esmaeel , Tadjfar Mehran , Najafi Saman
Published: March 2013

Purpose

The purpose of this paper is to investigate the flow around Parastoo UAV's wing, with the aim of improving its aerodynamic performance. A major source of concern is the use of relatively large flaps in the original design. This unmanned aerial vehicle (UAV) operates at low Reynolds numbers of below 500,000 and was designed for short‐range reconnaissance.

Design/methodology/approach

A finite volume solver is utilized to investigate the flow over different wing designs to find a replacement for the current one. To check the accuracy of this numerical modeling, the authors first duplicate the conditions of available relevant experiments. The numerical results are in good agreement with the wind tunnel experiments. Here, the aerodynamic performances of Parastoo's wing at different flight conditions with and without the proposed modification are studied and compared.

Findings

As the original design of Parastoo uses relatively large flaps, it is found that the aerodynamic performance of Parastoo is significantly hampered due to their existence. The use of a new wing cross‐section can improve the aerodynamics efficiency of Parastoo. It is recommended that FX‐63137 airfoil is a more suitable cross section instead of Parastoo's original NACA‐63215 airfoil. It is shown that this change improves the aerodynamic performance of the UAV and with the use of smaller flaps (changing the flaperons to only ailerons), the existing payload weight can be increased by 90 per cent.

Originality/value

The issues discussed for this UAV may be of use for other small unmanned plane designers. The numerical data generated for this study are useful for other design teams, both as in direct uses of the data in their own designs and/or for the validation of their numerical methods before investigating other wing designs.