158 research outputs found

    El propósito de la educación superior para el desarrollo humano y social en el contexto de la globalización

    Get PDF
    La globalización presenta un contexto especialmente estimulante para reexaminar el propósito educativo de la educación superior (ES) para el desarrollo humano, comunitario y social. En primer lugar, el desarrollo en sí mismo raramente recibe la atención directa de la mayor parte de las instituciones de educación superior (IES). Dado que el objetivo primordial de la ES es el desarrollo intelectual y moral, no es únicamente algo muy extraño, sino también algo que se vuelve cada vez más problemático e incluso éticamente indefendible. A la vista de las complejidades de este final de la era moderna, en la que tanto las «ventajas» como los «inconvenientes» circulan por el mundo cada vez con mayor frecuencia y tienen impactos cada vez más destructores tanto en la naturaleza como en las sociedades, se hace cada vez más evidente que son precisas con urgencia nuevas formas de «ver» el mundo y de «resolver» los problemas si queremos conseguir para las sociedades de todo el mundo un futuro sostenible. Si, como mantiene el argumento principal de este artículo, los humanos nos hemos convertido en víctimas de nuestras inadecuaciones paradigmáticas de tal modo que ahora está en peligro la misma sostenibilidad de la vida en la Tierra, entonces la educación superior tiene la obligación de hacer todo lo posible para transformar las ideas epistemológicas preestablecidas dominantes y liberar el desarrollo humano y social en la búsqueda más profunda de una vida reflexiva y responsable.Peer Reviewe

    The impact of variations in subject geometry, respiration and coil repositioning on the specific absorption rate in parallel transmit abdominal imaging at 7 T

    Get PDF
    Parallel transmit MRI at 7 T has increasingly been adopted in research projects and provides increased signal‐to‐noise ratios and novel contrasts. However, the interactions of fields in the body need to be carefully considered to ensure safe scanning. Recent advances in physically flexible body coils have allowed for high‐field abdominal imaging, but the effects of increased variability on energy deposition need further exploration. The aim of this study was to assess the impact of subject geometry, respiration phase and coil positioning on the specific absorption rate (SAR). Ten healthy subjects (body mass index [BMI] = 25 ± 5 kg m−2) were scanned (at 3 T) during exhale breath‐hold and images used to generate body models. Seven of these subjects were also scanned during inhale. Simplifications of the coil and body models were first explored, and then finite‐difference time‐domain simulations were run with a typical eight‐channel parallel transmit coil positioned over the abdomen. Simulations were used to generate 10 g averaged SAR (SAR10g) maps across 100,000 phase settings, and the worst‐case scenario 10 g averaged SAR (wocSAR10g) was identified using trigonometric maximisation. The average maximum SAR10g across the 10 subjects with 1 W input power per channel was 1.77 W kg−1. Hotspots were always close to the body surface near the muscle wall boundary. The wocSAR10g across the 10 subjects ranged from 2.3 to 3.2 W kg−1 and was inversely correlated to fat volume percentage (R = 8) and BMI (R = 0.6). The coefficient of variation values in SAR10g due to variations in subject geometry, respiration phase and realistic coil repositioning were 12%, 4% and 12%, respectively. This study found that the variability due to realistic coil repositioning was similar to the variability due to differing healthy subject geometries for abdominal imaging. This is important as it suggests that population‐based modelling is likely to be more useful than individual modelling in setting safe thresholds for abdominal imaging

    Isotropic-nematic phase equilibria in the Onsager theory of hard rods with length polydispersity

    Full text link
    We analyse the effect of a continuous spread of particle lengths on the phase behavior of rodlike particles, using the Onsager theory of hard rods. Our aim is to establish whether ``unusual'' effects such as isotropic-nematic-nematic (I-N-N) phase separation can occur even for length distributions with a single peak. We focus on the onset of I-N coexistence. For a log-normal distribution we find that a finite upper cutoff on rod lengths is required to make this problem well-posed. The cloud curve, which tracks the density at the onset of I-N coexistence as a function of the width of the length distribution, exhibits a kink; this demonstrates that the phase diagram must contain a three-phase I-N-N region. Theoretical analysis shows that in the limit of large cutoff the cloud point density actually converges to zero, so that phase separation results at any nonzero density; this conclusion applies to all length distributions with fatter-than-exponentail tails. Finally we consider the case of a Schulz distribution, with its exponential tail. Surprisingly, even here the long rods (and hence the cutoff) can dominate the phase behaviour, and a kink in the cloud curve and I-N-N coexistence again result. Theory establishes that there is a nonzero threshold for the width of the length distribution above which these long rod effects occur, and shows that the cloud and shadow curves approach nonzero limits for large cutoff, both in good agreement with the numerical results.Comment: 20 pages, 13 figure

    Calibration-free regional RF shims for MRS

    Get PDF
    Purpose: Achieving a desired RF transmit field (B1+) in small regions-of-interest (ROIs) is critical for single-voxel MR spectroscopy at ultra-high field. RF shimming, using parallel transmission, requires B1+ mapping and optimisation, which limits its ease-of-use. This work aimed to generate calibration-free RF shims for pre-defined target ROIs, which can be applied to any participant, to produce a desired absolute magnitude B1+ (|B1+|).Methods: RF shims were found offline by joint-optimisation on a database, comprising B1+ maps from 11 subjects, considering ROIs in occipital cortex (OCC), hippocampus (Hippo.) and posterior-cingulate (PCC), as well as whole brain. The |B1+| achieved was compared to a tailored shimming approach, and MR spectra were acquired using tailored and calibration-free shims in 4 participants. Global and local 10g specific absorption rate (SAR) deposition were estimated using Duke and Ella dielectric models.Results: There was no difference in the mean |B1+| produced using calibration-free vs. tailored RF shimming in OCC (p=0.15), Hippo. (p=0.5) or PCC (p=0.98) although differences were observed in the root-mean-square error (RMSE) |B1+|. Spectra acquired using calibration-free shims had similar SNR and low residual water signal. Under identical power settings, SAR deposition was lower compared to operating in quadrature mode. For example, total head SAR was around 35% less for OCC.Conclusion: This work demonstrates that static RF shims, optimised offline for small regions, avoid the need for B1+ mapping and optimisation for each ROI and participant. Furthermore, power settings may be increased when using calibration-free shims to better take advantage of RF shimming

    Prime Focus Spectrograph - Subaru's future -

    Full text link
    The Prime Focus Spectrograph (PFS) of the Subaru Measurement of Images and Redshifts (SuMIRe) project has been endorsed by Japanese community as one of the main future instruments of the Subaru 8.2-meter telescope at Mauna Kea, Hawaii. This optical/near-infrared multi-fiber spectrograph targets cosmology with galaxy surveys, Galactic archaeology, and studies of galaxy/AGN evolution. Taking advantage of Subaru's wide field of view, which is further extended with the recently completed Wide Field Corrector, PFS will enable us to carry out multi-fiber spectroscopy of 2400 targets within 1.3 degree diameter. A microlens is attached at each fiber entrance for F-ratio transformation into a larger one so that difficulties of spectrograph design are eased. Fibers are accurately placed onto target positions by positioners, each of which consists of two stages of piezo-electric rotary motors, through iterations by using back-illuminated fiber position measurements with a wide-field metrology camera. Fibers then carry light to a set of four identical fast-Schmidt spectrographs with three color arms each: the wavelength ranges from 0.38 {\mu}m to 1.3 {\mu}m will be simultaneously observed with an average resolving power of 3000. Before and during the era of extremely large telescopes, PFS will provide the unique capability of obtaining spectra of 2400 cosmological/astrophysical targets simultaneously with an 8-10 meter class telescope. The PFS collaboration, led by IPMU, consists of USP/LNA in Brazil, Caltech/JPL, Princeton, & JHU in USA, LAM in France, ASIAA in Taiwan, and NAOJ/Subaru.Comment: 13 pages, 11 figures, submitted to "Ground-based and Airborne Instrumentation for Astronomy IV, Ian S. McLean, Suzanne K. Ramsay, Hideki Takami, Editors, Proc. SPIE 8446 (2012)

    The Top 100 questions for the sustainable intensification of agriculture in India’s rainfed drylands

    Get PDF
    India has the largest area of rainfed dryland agriculture globally, with a variety of distinct types of farming systems producing most of its coarse cereals, food legumes, minor millets, and large amounts of livestock. All these are vital for national and regional food and nutritional security. Yet, the rainfed drylands have been relatively neglected in mainstream agricultural and rural development policy. As a result, significant social-ecological challenges overlap in these landscapes: endemic poverty, malnutrition and land degradation. Sustainable intensification of dryland agriculture is essential for helping to address these challenges, particularly in the context of accelerating climate change. In this paper, we present 100 questions that point to the most important knowledge gaps and research priorities. If addressed, these would facilitate and inform sustainable intensification in Indian rainfed drylands, leading to improved agricultural production and enhanced ecosystem services. The horizon scanning method used to produce these questions brought together experts and practitioners involved in a broad range of disciplines and sectors. This exercise resulted in a consolidated set of questions covering the agricultural drylands, organized into 13 themes. Together, these represent a collective programme for new cross- and multi-disciplinary research on sustainable intensification in the Indian rainfed drylands

    Systems thinking : an approach for understanding 'eco-agri-food systems'

    Get PDF
    The TEEBAgriFood ‘Scientific and Economic Foundations’ report addresses the core theoretical issues and controversies underpinning the evaluation of the nexus between the agri-food sector, biodiversity and ecosystem services and externalities including human health impacts from agriculture on a global scale. It argues the need for a ‘systems thinking‘ approach, draws out issues related to health, nutrition, equity and livelihoods, presents a Framework for evaluation and describes how it can be applied, and identifies theories and pathways for transformational change

    Beyond feedback: introducing the 'engagement gap' in organizational energy management

    Get PDF
    This paper discusses socio-technical relationships between people, organizations and energy in workplaces. Inspired by Sherry Arnstein’s ladder of citizen participation, it explores widening energy management beyond energy managers to other employees, introducing the idea of an ‘engagement gap’ to support a move beyond unidirectional forms of engagement (e.g. feedback and nudging) to more socially interactive processes. Results are drawn from two projects researching energy practices in public authorities and retail organizations. The first project, ‘GoodDeeds’, collaboratively created an information and communication technology tool and explored participatory processes within a municipality. The second project, Working with Infrastructure, Creation of Knowledge, and Energy strategy Development (WICKED), explored energy management in retail companies. The paper uses a ‘4Cs’ framework to articulate the influences of concerns, capacities and technical conditions within organizational communities. The results concur with previous research that energy management sits against a backdrop of competing organizational, institutional and political concerns. New data reveal discrepancies across organizations with regard to energy management capacities and technical metering conditions. The authors suggest employee engagement can be broadened by treating energy as a communal subject for discussion, negotiation and partnership. This objective moves beyond the ‘information-deficit’ approach intrinsic in the existing focus on analytics, dashboards and feedback
    corecore