2,913 research outputs found
Struggling to Learn, Learning to Struggle: Strategy and Structure in the 2010-11 University of Puerto Rico Student Strike
From April 2010 to March 2011, the University of Puerto Rico (UPR) underwent a two-phase strike sequence against neoliberal austerity measures. Altogether, that process resulted in the eventual concession of all of the students’ main demands, an unprecedented feat at the UPR, and a rare one in Puerto Rican history in general. In this dissertation I seek to cast light on this improbable event by examining, first, how neoliberalization patterned and contoured the choices facing the century-old UPR student movement. Second, I explore how interactions within the movement, including the framing contest among leadership teams and their interaction with the movement grassroots, affected the way in which those decisions were made. Focusing on a political cadre organization, the Union of Socialist Youths (UJS), which has been involved in the UPR since the mid-1970s, I conducted targeted, semi-structured interviews with members of the UJS, several of whom were first-generation working-class students first drawn to the movement by the on campus “movement building” activities of political cadre. Complementing my own critical participant observation with these interviews, as well as archival and documentary research, I built a reflexive, extended case study based on a reiterated problem-solving or learning process model. In summary, without arguing causation, I show that: 1) reforms implemented by administrators named by both governing parties since 1981 constitute a more or less coherent repertoire consistent with neoliberalization; 2) debates within the UPR student movement around critical switchpoints before and during the 2010-11 strike revolved around an apparent tradeoff between militant “pressure” and mass appeal, aspects of which are made salient by neoliberalizing repertoires (a recurring combination of strategic dilemmas that I call the “neoliberal dilemma”); 3) the UJS and other cadre organizations intervened in these debates in ways that strengthened the strategic capacity of the movement as a whole; and 4) the 2010-11 UPR strike is in turn part of a longer problem-solving sequence extending back to at least 1981, which in turn is part of the longer trajectory of the nested UPR student movement field, and the broader trajectory of resistance to colonial capitalism in Puerto Rico
NADPH Oxidase-Dependent Superoxide Production in Plant Reproductive Tissues
In the life cycle of a flowering plant, the male gametophyte (pollen grain) produced in the anther reaches the stigmatic surface and initiates the pollen–pistil interaction, an important step in plant reproduction, which ultimately leads to the delivery of two sperm cells to the female gametophyte (embryo sac) inside the ovule. The pollen tube undergoes a strictly apical expansion characterized by a high growth rate, whose targeting should be tightly regulated. A continuous exchange of signals therefore takes place between the haploid pollen and diploid tissue of the pistil until fertilization. In compatible interactions, theses processes result in double fertilization to form a zygote (2n) and the triploid endosperm. Among the large number of signaling mechanisms involved, the redox network appears to be particularly important. Respiratory burst oxidase homologs (Rbohs) are superoxide-producing enzymes involved in a broad range of processes in plant physiology. In this study, we review the latest findings on understanding Rboh activity in sexual plant reproduction, with a particular focus on the male gametophyte from the anther development stages to the crowning point of fertilization. Rboh isoforms have been identified in both the male and female gametophyte and have proven to be tightly regulated. Their role at crucial points such as proper growth of pollen tube, self-incompatibility response and eventual fertilization is discussed. [EN]European Regional Development Fund (ERDF) co-financed grants: BFU2008-006292, BFU2011-22779, CSIC-201540E065, and RECUPERA2020-3.1.4.Peer reviewe
A Dynamic Kinetic Asymmetric Heck Reaction for the Simultaneous Generation of Central and Axial Chirality
A highly diastereo- and enantioselective, scalable Pd-catalyzed dynamic kinetic asymmetric Heck reaction of heterobiaryl sulfonates with electron-rich olefins is described. The coupling of 2,3-dihydrofuran or N-boc protected 2,3-dihydropyrrole with a variety of quinoline, quinazoline, phthalazine, and picoline derivatives takes place with simultaneous installation of central and axial chirality, reaching excellent diastereo- and enantiomeric excesses when in situ formed [Pd0/DM-BINAP] was used as the catalyst, with loadings reduced down to 2 mol % in large scale reactions. The coupling of acyclic, electron-rich alkenes can also be performed using a [Pd0/Josiphos ligand] to obtain axially chiral heterobiaryl α-substituted alkenes in high yields and enantioselectivities. Products from Boc-protected 2,3-dihydropyrrole can be easily transformed into N,N ligands or appealing axially chiral, bifunctional proline-type organocatalysts. Computational studies suggest that a β-hydride elimination is the stereocontrolling step, in agreement with the observed stereochemical outcome of the reaction.Ministerio de Ciencia e Innovación (Grants CTQ2016-76908-C2-1-P; CTQ2016-76908-C2-2-P; CTQ2016-78083-P; RYC-2013-12585)European Commission (FEDER Programme)Junta de Andalucía (Grant 2012/FQM 10787)Universidad de Sevilla (Grant No. 1800511201)European Union - Marie Skłodowska-Curie (COFUND—Grant Agreement nº 291780
Sedimentary Characteristics of the Holocene Tsunamigenic Deposits in the Coastal Systems of the Cadiz Gulf (Spain)
DESIGN AND INTEGRATION OF A HUMAN-ROBOT PHYSICAL INTERACTION PLATFORM WITH PURPOSES OF MEDICAL DIAGNOSIS AND REHABILITATION OF UPPER LIMB
In this paper a human-robot physical interaction system with purposes of diagnosis and rehabilitation of upper limb is proposed.Anunderactuatedhaptic device with six degrees of freedom is used, with low inertia and low joint friction.Adaptive control technique is used for passive haptic guidance and active exploration, in order to compensate the dynamic uncertainty of the human operator in the loop.To validate the experimental platform, a procedure is established with three steps: i) knowledge of the haptic interface (interaction with the kinematic virtual environment), ii) navigation in a virtual pipe with changes in the geometric characteristics (verification of position, velocity, collisions and runtime), and iii) haptic guidance in a structured path based on a clinical protocol (study of convergence and energy).Environmental conditions such as temperature, humidity, lighting and noise are characterizedwith purposes to define experimental conditions.In this work, we assess based on the NASA-TLX protocol,the workload perception of simple temporal-spatial tasks
DESIGN AND INTEGRATION OF A HUMAN-ROBOT PHYSICAL INTERACTION PLATFORM WITH PURPOSES OF MEDICAL DIAGNOSIS AND REHABILITATION OF UPPER LIMB
In this paper a human-robot physical interaction system with purposes of diagnosis and rehabilitation of upper limb is proposed.Anunderactuatedhaptic device with six degrees of freedom is used, with low inertia and low joint friction.Adaptive control technique is used for passive haptic guidance and active exploration, in order to compensate the dynamic uncertainty of the human operator in the loop.To validate the experimental platform, a procedure is established with three steps: i) knowledge of the haptic interface (interaction with the kinematic virtual environment), ii) navigation in a virtual pipe with changes in the geometric characteristics (verification of position, velocity, collisions and runtime), and iii) haptic guidance in a structured path based on a clinical protocol (study of convergence and energy).Environmental conditions such as temperature, humidity, lighting and noise are characterizedwith purposes to define experimental conditions.In this work, we assess based on the NASA-TLX protocol,the workload perception of simple temporal-spatial tasks
Production of Transglutaminase by Streptoverticillium ladakanum NRRL-3191 Using Glycerol as Carbon Source
The enzyme transglutaminase (TG) catalyses the formation of covalent bonds between adjacent proteins, thereby improving the gel structure of proteins and has important applications for the food industry. The aims of this work were: (i) to elucidate the effect of agitation speed during the biotechnological production of TG by Streptoverticillium ladakanum NRRL-3191 using glycerol as carbon source; and (ii) to improve TG production by optimising the composition of media based on glycerol, xylose and casein. An agitation speed of 250 rpm and a fermentation time of 72 h resulted in the optimal enzymatic activity (0.628 U/mL) with a productivity of 0.087 U/(mL·h). The composition of media with glycerol, xylose and casein were optimised using an experimental design to improve TG production. The model predicts that the maximum TG activity (0.725 U/mL) can be obtained using glycerol 50.5 g/L and casein 20 g/L without the addition of xylose
Identification of the HSP70-II gene in Leishmania braziliensis HSP70 locus: genomic organization and UTRs characterization
<p>Abstract</p> <p>Background</p> <p>The heat stress suffered by <it>Leishmania sp </it>during its digenetic life-cycle is a key trigger for its stage differentiation. In <it>Leishmania </it>subgenera two classes of <it>HSP70 </it>genes differing in their 3' UTR were described. Although the presence of <it>HSP70</it>-<it>I </it>genes was previously suggested in <it>Leishmania (Viannia) braziliensis</it>, <it>HSP70</it>-<it>II </it>genes had been reluctant to be uncovered.</p> <p>Results</p> <p>Here, we report the existence of two types of <it>HSP70 </it>genes in <it>L. braziliensis </it>and the genomic organization of the <it>HSP70 </it>locus. RT-PCR experiments were used to map the untranslated regions (UTR) of both types of genes. The 3' UTR-II has a low sequence identity (55-57%) when compared with this region in other <it>Leishmania </it>species. In contrast, the 5' UTR, common to both types of genes, and the 3' UTR-I were found to be highly conserved among all <it>Leishmania </it>species (77-81%). Southern blot assays suggested that <it>L. braziliensis </it><it>HSP70 </it>gene cluster may contain around 6 tandemly-repeated <it>HSP70</it>-<it>I </it>genes followed by one <it>HSP70</it>-<it>II </it>gene, located at chromosome 28. Northern blot analysis indicated that levels of both types of mRNAs are not affected by heat shock.</p> <p>Conclusions</p> <p>This study has led to establishing the composition and structure of the HSP70 locus of <it>L. braziliensis</it>, complementing the information available in the GeneDB genome database for this species. <it>L. braziliensis </it><it>HSP70 </it>gene regulation does not seem to operate by mRNA stabilization as occurs in other <it>Leishmania </it>species.</p
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