7,315 research outputs found

    Contrastive grammar : a theory and practice handbook

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    En consonancia con los lineamientos del programa vigente de Gramática Contrastiva, materia incluida en el programa de estudios del Traductorado de Inglés de la Facultad de Lenguas, Universidad Nacional de Córdoba, el objetivo principal de Contrastive Grammar: A Theory and Practice Handbook es brindar a los estudiantes un manual que combine las gramáticas descriptivas del inglés y del español. No pretende ser una revisión completa de todas las diferencias lingüísticas existentes entre ambas lenguas: por el contrario, el objetivo del presente manual es combinar información teórica clave con prácticas variadas respecto de estructuras dispares que representan la fuente más frecuente de interferencia entre los dos sistemas.Fil: Gómez Calvillo, M. Natalia. Universidad Nacional de Córdoba. Facultad de Lenguas; Argentina.Fil: Meehan, Patricia. Universidad Nacional de Córdoba. Facultad de Lenguas; Argentina.Fil: Díaz, M. Josefina. Universidad Nacional de Córdoba. Facultad de Lenguas; Argentina.Fil: Rolfi, Laura. Universidad Nacional de Córdoba. Facultad de Lenguas; Argentina

    Small heat-shock proteins: important players in regulating cellular proteostasis

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    Small heat-shock proteins (sHsps) are a diverse family of intra-cellular molecular chaperone proteins that play a critical role in mitigating and preventing protein aggregation under stress conditions such as elevated temperature, oxidation and infection. In doing so, they assist in the maintenance of protein homeostasis (proteostasis) thereby avoiding the deleterious effects that result from loss of protein function and/or protein aggregation. The chaperone properties of sHsps are therefore employed extensively in many tissues to prevent the development of diseases associated with protein aggregation. Significant progress has been made of late in understanding the structure and chaperone mechanism of sHsps. In this review, we discuss some of these advances, with a focus on mammalian sHsp hetero-oligomerisation, the mechanism by which sHsps act as molecular chaperones to prevent both amorphous and fibrillar protein aggregation, and the role of post-translational modifications in sHsp chaperone function, particularly in the context of disease.SM was supported by a Royal Society Dorothy Hodgkin Fellowship, HE is supported by an Australian Research Council Future Fellowship (FT110100586) and JC is supported by a National Health and Medical Research Council Project Grant (#1068087)

    Visual clues act as a substitute for haptic feedback in robotic surgery

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    Objective: The lack of haptic feedback (HF) in robotic surgery is one of the major concerns of novice surgeons to that field. The superior visual appearances acquired during robotic surgery may give clues that make HF less important. Methods: We surveyed 52 individuals on their perception of HF during robotic surgery. The first group of 34 surgically inexperienced people used the da Vinci robot for their first time (drylab). The second group included 8 laparoscopic surgeons with experience up to a fifth robotic operation. The third group included 10 surgical experts with substantial experience (150-650 robotic cases). Visual analog assessment was made of perception of HF, how much HF was missed, how much the absence of HF impaired the operators' level of comfort. Robotic experts were asked if complications have occurred as a result of a lack of HF. Results: Of the first group, 50% reported the perception of HF, as did 55% of the second group and 100% of the third group (difference between group 1 and group 3: p<0.05). The first group missed HF for 6.5; the second group for 4.3, and the third group for 4 (difference between groups 1 and 3: p<0.05). The surgical experts claimed to have missed HF for 7.2 s when they first started robotic surgery (Difference to now: p<0.05). The lack of HF caused discomfort for the first group of 4; for the second group of 4,4, and for the third group of 2,6. One complication was reported by the robotic experts as resulting from the lack of HF. Conclusions: The data support the conclusion that even beginners quickly experience the perception of HF when performing robotic surgery. With more experience, perception of HF and the level of comfort with robotic surgery increases significantly. This perception of HF makes "real” HF less important and demonstrates that its importance is overestimated by novices in robotic surger

    Deliberative democracy and the politics of redistribution: the case of the Indian Panchayats

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    By examining evidence from India, where quotas for women in local government were introduced in 1993, this article argues that institutional reform can disturb hegemonic discourses sufficiently to open a window of opportunity where deliberative democratic norms take root and where, in addition to the politics of recognition, the politics of redistribution also operates

    The visual, the auditory and the haptic – A user study on combining modalities in virtual worlds

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    Fröhlich J, Wachsmuth I. The visual, the auditory and the haptic – A user study on combining modalities in virtual worlds. In: Shumaker R, ed. Virtual Augmented and Mixed Reality. Designing and Developing Augmented and Virtual Environments. Lecture Notes in Computer Science. Vol 8021. Berlin, Heidelberg: Springer Berlin Heidelberg; 2013: 159-168.In order to make a step further towards understanding the impact of multi-modal stimuli in Virtual Reality we conducted a user study with 80 participants performing tasks in a virtual pit environment. Participants were divided into four groups, each presented a different combination of multi-sensory stimuli. Those included real-time 3D graphics, audio stimuli (ambient, static and event sounds), and haptics consisting of wind and tactile feedback when touching objects. A presence questionnaire was used to evaluate subjectively reported presence on the one hand, and on the other physiological sensors were used to measure heart rate and skin conductance as an objective measure. Results strongly indicate that an increase of modalities does not automatically result in an increase of presence

    Expressional alterations in functional ultra-conserved non-coding rnas in response to all-trans retinoic acid - induced differentiation in neuroblastoma cells.

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    BACKGROUND: Ultra-conserved regions (UCRs) are segments of the genome (≥ 200 bp) that exhibit 100% DNA sequence conservation between human, mouse and rat. Transcribed UCRs (T-UCRs) have been shown to be differentially expressed in cancers versus normal tissue, indicating a possible role in carcinogenesis. All-trans-retinoic acid (ATRA) causes some neuroblastoma (NB) cell lines to undergo differentiation and leads to a significant decrease in the oncogenic transcription factor MYCN. Here, we examine the impact of ATRA treatment on T-UCR expression and investigate the biological significance of these changes. METHODS: We designed a custom tiling microarray to profile the expression of 481 T-UCRs in sense and anti-sense orientation (962 potential transcripts) in untreated and ATRA-treated neuroblastoma cell lines (SH-SY5Y, SK-N-BE, LAN-5). Following identification of significantly differentially expressed T-UCRs, we carried out siRNA knockdown and gene expression microarray analysis to investigate putative functional roles for selected T-UCRs. RESULTS: Following ATRA-induced differentiation, 32 T-UCRs were differentially expressed (16 up-regulated, 16 down-regulated) across all three cell lines. Further insight into the possible role of T-UC.300A, an independent transcript whose expression is down-regulated following ATRA was achieved by siRNA knockdown, resulting in the decreased viability and invasiveness of ATRA-responsive cell lines. Gene expression microarray analysis following knockdown of T-UC.300A revealed a number of genes whose expression was altered by changing T-UC.300A levels and that might play a role in the increased proliferation and invasion of NB cells prior to ATRA-treatment. CONCLUSIONS: Our results indicate that significant numbers of T-UCRs have altered expression levels in response to ATRA. While the precise roles that T-UCRs might play in cancer or in normal development are largely unknown and an important area for future study, our findings strongly indicate that the function of non-coding RNA T-UC.300A is connected with proliferation, invasion and the inhibition of differentiation of neuroblastoma cell lines prior to ATRA treatment

    The Ionization Fraction in Dense Molecular Gas II: Massive Cores

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    We present an observational and theoretical study of the ionization fraction in several massive cores located in regions that are currently forming stellar clusters. Maps of the emission from the J = 1-> O transitions of C18O, DCO+, N2H+, and H13CO+, as well as the J = 2 -> 1 and J = 3 -> 2 transitions of CS, were obtained for each core. Core densities are determined via a large velocity gradient analysis with values typically 10^5 cm^-3. With the use of observations to constrain variables in the chemical calculations we derive electron fractions for our overall sample of 5 cores directly associated with star formation and 2 apparently starless cores. The electron abundances are found to lie within a small range, -6.9 < log10(x_e) < -7.3, and are consistent with previous work. We find no difference in the amount of ionization fraction between cores with and without associated star formation activity, nor is any difference found in electron abundances between the edge and center of the emission region. Thus our models are in agreement with the standard picture of cosmic rays as the primary source of ionization for molecular ions. With the addition of previously determined electron abundances for low mass cores, and even more massive cores associated with O and B clusters, we systematically examine the ionization fraction as a function of star formation activity. This analysis demonstrates that the most massive sources stand out as having the lowest electron abundances (x_e < 10^-8).Comment: 35 pages (8 figures), using aaspp4.sty, to be published in Astrophysical Journa

    The extremely collimated bipolar H_2O jet from the NGC 1333-IRAS 4B protostar

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    We have performed observations of water maser emission towards a sample of low-mass protostars, in order to investigate the properties of jets associated with the earliest stages of star formation and their interaction with the surrounding medium. The main aim is to measure the absolute positions and proper motions of the H_2O spots in order to investigate the kinematics of the region from where the jet is launched. We imaged the protostars in the nearby region NGC 1333-IRAS 4 in the water maser line at 22.2 GHz by using the VLBA in phase-reference mode at the milliarcsecond scale over four epochs, spaced by one month to measure proper motions. Two protostars (A2 and B) were detected in a highly variable H_2O maser emission, with an active phase shorter than four weeks. The H_2O maps allow us to trace the fast jet driven by the B protostar: we observed both the red- and blue-shifted lobes very close to the protostar, =< 35 AU, moving away with projected velocities of ~10-50 km/s. The comparison with the molecular outflow observed at larger scale suggests a jet precession with a 18'/yr rate. By measuring the positional spread of the H_2O spots we estimate a jet width of ~2 AU at a distance of ~12 AU from the driving protostar.Comment: 9 pages, 8 figures, A&A accepte
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