233 research outputs found

    Effects of Orientations, Aspect Ratios, Pavement Materials and Vegetation Elements on Thermal Stress inside Typical Urban Canyons

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    The analysis of local climate conditions to test artificial urban boundaries and related climate hazards through modelling tools should become a common practice to inform public authorities about the benefits of planning alternatives. Different finishing materials and sheltering objects within urban canyons (UCs) can be tested, predicted and compared through quantitative and qualitative understanding of the relationships between the microclimatic environment and subjective thermal assessment. This process can work as support planning instrument in the early design phases as has been done in this study that aims to analyze the thermal stress within typical UCs of Bilbao (Spain) in summertime through the evaluation of Physiologically Equivalent Temperature using ENVI-met. The UCs are characterized by different orientations, height-to-width aspect ratios, pavement materials, trees’ dimensions and planting pattern. Firstly, the current situation was analyzed; secondly, the effects of asphalt and red brick stones as streets’ pavement materials were compared; thirdly, the benefits of vegetation elements were tested. The analysis demonstrated that orientation and aspect ratio strongly affect the magnitude and duration of the thermal peaks at pedestrian level; while the vegetation elements improve the thermal comfort up to two thermophysiological assessment classes. The outcomes of this study, were transferred and visualized into green planning recommendations for new and consolidated urban areas in Bilbao.The work leading to these results has received funding from COST Action TU0902, the European Community’s Seventh Framework Programme under Grant Agreement No. 308497, Project RAMSES—Reconciling Adaptation, Mitigation and Sustainable Development for Cities (2012–2017) and Diputación Foral de Bizkaia Exp. 6-12-TK-2010-0027, Project SICURB-ITS- Desarrollo de Sistemas para el análisis de la Contaminación atmosférica en zonas URBanas integrados en ITS (2010–2011)

    Presence of 3d Quadrupole Moment in LaTiO3 Studied by 47,49Ti NMR

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    Ti NMR spectra of LaTiO3 are reexamined and the orbital state of this compound is discussed. The NMR spectra of LaTiO3 taken at 1.5 K under zero external field indicate a large nuclear quadrupole splitting. This splitting is ascribed to the presence of the rather large quadrupole moment of 3d electrons at Ti sites, suggesting that the orbital liquid model proposed for LaTiO3 is inappropriate. The NMR spectra are well explained by the orbital ordering model expressed approximately as 1/3(dxy+dyz+dzx)1/\sqrt{3}(d_{xy}+d_{yz}+d_{zx}) originating from a crystal field effect. It is also shown that most of the orbital moment is quenched.Comment: 4 pages, 3 fugures; to appear in Phys. Rev. Let

    Comprehensive airborne characterization of aerosol from a major bovine source

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    We report an extensive airborne characterization of aerosol downwind of a massive bovine source in the San Joaquin Valley (California) on two flights during July 2007. The Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter probed chemical composition, particle size distribution, mixing state, sub- and supersaturated water uptake behavior, light scattering properties, and the interrelationship between these parameters and meteorology. Total PM_(1.0) levels and concentrations of organics. nitrate. and ammonium were enhanced in the plume from the source as compared to the background aerosol. Organics dominated the plume aerosol mass (~56-64%), followed either by sulfate or nitrate. and then ammonium. Particulate amines were detected in the plume aerosol by a particle-into-liquid sampler (PILS) and via mass spectral inarkers in the Aerodvne C-ToF-AMS. Amines were found to be a significant atmospheric base even in the presence of arnmonia; particulate amine concentrations are estimated as at least 14-23% of that of ammonium in the plume. Enhanced sub- and supersaturated water uptake and reduced refractive indices were coincident with lower organic mass fractions, higher nitrate mass fractions, and the detection of amines. The likelihood of suppressed droplet growth owing to kinetic limitations from hydrophobic organic material is explored. After removing effects associated with size distribution and mixing state, the normalized activated fraction of cloud condensation nuclei (CCN) increased as a function of the subsaturated hygroscopic growth factor, with the highest activated fractions being consistent with relatively lower organic mass fractions and higher nitrate mass fractions. Subsaturated hygroscopic growth factors for the organic fraction of the aerosol are estimated based on employing the Zdanovskii-Stokes Robinson (ZSR) mixing rule. Representative values for a parameterization treating particle water uptake in both the sub- and supersaturated regimes are reported for incorporation into atmospheric models

    Law Libraries and Laboratories: The Legacies of Langdell and His Metaphor

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    Law Librarians and others have often referred to Harvard Law School Dean C.C. Langdell’s statements that the law library is the lawyer’s laboratory. Professor Danner examines the context of what Langdell through his other writings, the educational environment at Harvard in the late nineteenth century, and the changing perceptions of university libraries generally. He then considers how the “laboratory metaphor” has been applied by librarians and legal scholars during the twentieth century and into the twenty-first. The article closes with thoughts on Langdell’s legacy for law librarians and the usefulness of the laboratory metaphor

    The Present State of the Use of Waste Wood Ash as an Eco-Efficient Construction Material: A Review

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    [EN] A main global challenge is finding an alternative material for cement, which is a major source of pollution to the environment because it emits greenhouse gases. Investigators play a significant role in global waste disposal by developing appropriate methods for its effective utilization. Geopolymers are one of the best options for reusing all industrial wastes containing aluminosilicate and the best alternative materials for concrete applications. Waste wood ash (WWA) is used with other waste materials in geopolymer production and is found in pulp and paper, wood-burning industrial facilities, and wood-fired plants. On the other hand, the WWA manufacturing industry necessitates the acquisition of large tracts of land in rural areas, while some industries use incinerators to burn wood waste, which contributes to air pollution, a significant environmental problem. This review paper offers a comprehensive review of the current utilization of WWA with the partial replacement with other mineral materials, such as fly ash, as a base for geopolymer concrete and mortar production. A review of the usage of waste wood ash in the construction sector is offered, and development tendencies are assessed about mechanical, durability, and microstructural characteristics. The impacts of waste wood ash as a pozzolanic base for eco-concreting usages are summarized. According to the findings, incorporating WWA into concrete is useful to sustainable progress and waste reduction as the WWA mostly behaves as a filler in filling action and moderate amounts of WWA offer a fairly higher compressive strength to concrete. A detail study on the source of WWA on concrete mineralogy and properties must be performed to fill the potential research gap.S

    Sutureless Valve in Repeated Aortic Valve Replacement: Results from an International Prospective Registry

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    Objective: To report early and midterm results registry of patients undergoing repeated aortic valve replacement (RAVR) with sutureless prostheses from an international prospective registry (SURE-AVR). Methods: Between March 2011 and June 2019, 69 patients underwent RAVR with self-expandable sutureless aortic bioprostheses at 22 international cardiac centers.Results: Overall mortality was 2.9% with a predicted logistic EuroSCORE 11 of 10.7%. Indications for RAVR were structural valve dysfunction (84.1%) and infective prosthetic endocarditis (15.9%) and were performed in patients with previously implanted bioprostheses (79.7%), mechanical valves (15.9%), and transcatheter valves (4.3%). Minimally invasive approach was performed in 15.9% of patients. Rate of stroke was 1.4% and rate of early valve-related reintervention was 1.4%. Overall survival rate at 1 and 5 years was 97% and 91%, respectively. No major paravalvular leak occurred. Rate of pacemaker implantation was 5.8% and 0.9% per patient-year early and at follow-up, respectively. The mean transvalvular gradient at 1-year and 5-year follow-up was 10.5 mmHg and 11.5 mmHg with a median effective orifice area of 1.8 cm 2 and 1.8 cm 2 , respectively. Conclusions: RAVR with sutureless valves is a safe and effective approach and provides excellent clinical and hemodynamic results up to 5 years

    Clinical outcomes after implantation of a sutureless aortic bioprosthesis with concomitant mitral valve surgery: the SURE-AVR registry

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    Background: Early treatment of aortic valve stenosis is recommended in eligible symptomatic patients with severe aortic valve stenosis who would otherwise have a poor prognosis. The sutureless aortic valve bioprosthesis offers an alternative to standard aortic valve replacement with a sutured valve, but limited data are available in patients who have undergone multiple valve procedures involving the new, sutureless technology. We sought to investigate outcomes in high operative risk patients with previous or concomitant valve surgery who were implanted with a sutureless valve. Methods: SURE-AVR is an ongoing, prospective, multinational registry of patients undergoing aortic valve replacement. In-hospital and post-discharge outcomes up to 5 years were collected. Results: The study population comprised 78 patients (mean \ub1 SD: age 73.6 \ub1 7.6 years, logistic EuroSCORE 18.0 \ub1 17.5) enrolled at 13 sites who presented for concomitant or previous mitral valve repair (n\ua0= 45) or replacement (n\ua0= 33), with or without additional concomitant procedures, and were implanted with a sutureless valve. Mean \ub1 SD overall aortic cross-clamp time was 109 \ub1 41 min and cardiopulmonary bypass time was 152 \ub1 49 min. Mean \ub1 SD aortic pressure gradients decreased from 37.6 \ub1 17.7 mmHg preoperatively to 13.0 \ub1 5.7 mmHg at hospital discharge, and peak aortic pressure gradient from 61.5 \ub1 28.7 to 23.4 \ub1 10.6 mmHg. Early events included 1 death, 1 transient ischaemic attack, and 1 bleed (all 1.3%); a permanent pacemaker implantation was required in 6 patients (7.7%), and 2 reoperations (not valve related) (2.6%) took place. Over a median follow-up of 55.5 months (Q1 13.4, Q3 68.6), 12 patients died (6 cardiovascular and 6 non-cardiovascular, both 2.1% per patient-year). Five-year survival was 81.3%. Late paravalvular leak occurred in 2 patients (0.7% per patient-year) and permanent pacemaker implantation was required in 3 patients (0.1% per patient-year). There was no apparent rise in mean or peak aortic pressure gradient over the study. Conclusions: These results suggest that the sutureless implant is a technically feasible procedure during mitral surgery and is associated with good clinical outcomes

    The dynamic crossover in water does not require bulk water

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    Many of the anomalous properties of water may be explained by invoking a second critical point that terminates the coexistence line between the low- and high-density amorphous states in the liquid. Direct experimental evidence of this point, and the associated polyamorphic liquid–liquid transition, is elusive as it is necessary for liquid water to be cooled below its homogeneous-nucleation temperature. To avoid crystallization, water in the eutectic LiCl solution has been studied but then it is generally considered that “bulk” water cannot be present. However, recent computational and experimental studies observe cooperative hydration in which case it is possible that sufficient hydrogen-bonded water is present for the essential characteristics of water to be preserved. For femtosecond optical Kerr-effect and nuclear magnetic resonance measurements, we observe in each case a fractional Stokes–Einstein relation with evidence of the dynamic crossover appearing near 220 K and 250 K respectively. Spectra obtained in the glass state also confirm the complex nature of the hydrogen-bonding modes reported for neat room-temperature water and support predictions of anomalous diffusion due to “worm-hole” structure
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