1,142 research outputs found

    Signature of antiferromagnetic long-range order in the optical spectrum of strongly correlated electron systems

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    We show how the onset of a non-Slater antiferromagnetic ordering in a correlated material can be detected by optical spectroscopy. Using dynamical mean-field theory we identify two distinctive features: The antiferromagnetic ordering is associated with an enhanced spectral weight above the optical gap, and well separated spin-polaron peaks emerge in the optical spectrum. Both features are indeed observed in LaSrMnO_4 [G\"ossling et al., Phys. Rev. B 77, 035109 (2008)]Comment: 11 pages, 9 figure

    From infinite to two dimensions through the functional renormalization group

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    We present a novel scheme for an unbiased and non-perturbative treatment of strongly correlated fermions. The proposed approach combines two of the most successful many-body methods, i.e., the dynamical mean field theory (DMFT) and the functional renormalization group (fRG). Physically, this allows for a systematic inclusion of non-local correlations via the flow equations of the fRG, after the local correlations are taken into account non-perturbatively by the DMFT. To demonstrate the feasibility of the approach, we present numerical results for the two-dimensional Hubbard model at half-filling.Comment: 5 pages, 4 figure

    The case for hybrid ventilated primary schools in Ho Chi Minh City in Vietnam

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    This study investigates indoor environmental quality and users’ perception in 14 classrooms of a mixed-mode ventilated primary school in Ho Chi Minh City, Vietnam, during the rainy season by qualitative and quantitative research methods. Spot and long-term measurements were recorded, covering a range of environmental parameters such as air temperature, relative humidity, CO2 concentration level, illuminance and sound level. A questionnaire was conducted and answered by 451 children (eight to eleven year olds) to investigate their perception of the thermal and visual comfort, indoor air quality, noise and overall comfort in the classrooms. In addition, 14 teachers were asked to inform the study about their experiences and behaviours in the classrooms. The results were analysed by cross relating the measured environmental conditions and the comfort vote on a seven-point scale

    A review of the potential of smart homes to support independent living

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    Between 2015 and 2050, the proportion of the world's population over 60 years of age is expected to nearly double, from 12% to 22%. Whilst hospitals offer care to people with health problems, support at home is generally limited to carers, a costly labour intensive method that impacts on the ability of many elderly patients to live independently. This pushes the demand for housing that caters for elderly people allowing them to remain in their homes but with some level of healthcare support. In the UK, the domestic sector currently accounts for around 30% of total energy consumption and contributes in the region of 27% of total carbon dioxide and greenhouse gas emissions. With an ageing population, offering healthy environments with a cushion against rising energy prices will be essential for people spending most of their time at home and often living on limited budgets. In this context, the drive to reduce energy consumption and associated greenhouse gas emissions from housing has acted as a catalyst in the increasing installation of meters and sensors for monitoring energy use and indoor environmental conditions in buildings. These monitoring technologies can track and record a range of parameters such as temperature, air quality, occupant behaviour etc. Many of these could be optimised to help create environments that assist people such as the elderly to live at home. This paper aims to review relevant studies and technologies in the areas of smart, energy-efficient and lifetime homes, identifying some of the health needs of elderly people who could live at home if provided with adequate support, the range and type of technologies that could be employed to this objective, and suitable metrics to be used to measure the effectiveness of these technologies. The paper concludes that there is a limited evidence base on the health effects of energy-efficient homes, highlighting the need for more research and post occupancy evaluation using indoor environmental quality monitoring technology and wearable devices to analyse not only the energy performance of ‘green’ housing but also the possible effects of indoor environmental conditions on the subjective and objective wellbeing of occupants

    The case for internalising externalities in a sustainable rail asset base

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    Although the concept of sustainability and Sustainable development has tended to be mostly associated with the management of natural resources and the consequent environmental impact, the most accepted definition draws together its social, economic and environmental dimensions. The rail industry, as provider of a low carbon transport system, is well placed to have a significant role to play in promoting an environmental, economic and social balance that can be sustained and afforded for the foreseeable future. The paper suggests that a more comprehensive perspective on the scope of a sustainable intervention in rail infrastructure assets is needed, arguing that the necessary whole life evaluation process should include an additional positive externality: the uplift in knowledge, skill and expertise that comes about as a result of participation in projects and programmes. The inclusion of this benefit would provide a more accurate representation of value to support investment decision making and strengthen the case for a broader funding base. And that the demonstration of the correlation between participation in projects and programmes and the consequent uplift in skill, knowledge and expertise could be used to shift the emphasis in rail project planning

    The case for localised energy management to support resilient cities

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    Localised energy generation, ownership and management provide a mechanism to address issues of affordability, energy security, infrastructure resilience and the need to reduce greenhouse gases emissions. There is potential for the growth of community energy schemes in the UK. However, small to medium-sized schemes find it hard to compete with large energy providers. Energy Service Companies (ESCOs) are created to manage the local production and distribution of energy. In Nottingham, the Meadows Ozone Energy Services (MOZES) is a community owned organisation that aims to reduce their carbon footprint, support experimentation and learning in relation to sustainable energy, support energy self sufficiency, help to provide access to affordable energy, and contribute to socio-economic development. In this paper, the authors described some of the benefits that an ESCO can bring to a community drawing on examples from MOZES. The benefits and challenges associated with the implementation of community energy schemes were examined and the results of a questionnaire administered to residents of the Meadows community are presented for the first time. Conclusions are drawn and recommendations are made on how the model developed by MOZES in Nottingham can benefit other communities and contribute to resilient cities for the wider development of distributed energy storage in the UK

    The last Charrua Indian; (Uruguay): analysis of the remains of Chief Vaimaca Perú.

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    Uruguay is the only Latin American country that at present lacks Native populations and little is known about its prehistoric populations. In the construction of National identity, the unique reference to Natives is about Charra Indians, one of the most important ethnic groups that lived in the territory and exterminated in the 1830s. In 1833, four survivors were taken to be exhibited and studied in France, becoming martyrs and a symbol of their nation. The skeletal remains of Chief Perú were preserved and studied mainly by Rivet1; these are the only remains certainly identified as belonging to a Charrúa. In 2002, the French government returned the remains to Uruguay, where they were buried with honours at the National Pantheon. Before the burial, we performed morphological studies as well as extracted samples for DNA analysis. Peru's morphology is coherent with the one of a nomadic warrior: robust body with strong muscular insertions, wounds, and healthy diet based mainly on meat. Here we show that metric and morphological data as well as maternal inherited mitochondrial DNA (mtDNA) hypervariable region I (HVRI) and restriction fragment length polymorphisms (RFLPs), indicate a close relationship with Pampa-Patagonian Indians, and specially, with prehistoric Natives buried in mounds from eastern Uruguay. This last finding is particularly important to understand Uruguayan prehistory and history, raising the debate about who the mound builders were, and showing continuity between them, historic Charrúa Indians, and present populations

    An analysis of thermal comfort in primary schools in Vietnam

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    There is a trend of installing air conditioning systems in public primary schools that are currently naturally ventilated in Vietnam. A previous study conducted by the authors provided evidence that there is limited need for air conditioning in Vietnamese mid-season and the hottest season. In this study, the authors investigated thermal comfort and users’ perceptions in three primary schools in Ho Chi Minh City during the hottest season (April 2016) and the coldest season (December 2016 – January 2017). In-situ spot and long-term measurements were recorded. Questionnaires were completed by 3,960 children (age range from 8 to 11 years) and the teachers to inform the study about their experiences and the extent of their interaction with the building in 97 free-running classrooms. The results were analysed by correlating the conditions measured and the comfort mean votes. The neutral temperatures were respectively 31.7oC and 31.1oC for the hottest and coldest seasons. Children were observed to tolerate higher thermal comfort condition than the recommended values in the standards. Compared with the results of the hottest season, the thermal sensation mean vote reduced from (0.29) to (0.12) when the decrease of the mean temperature was from 33.3oC to 31.8oC in the coldest season. The temperature of 33oC was proposed for the overheating benchmark. The results indicated that Vietnamese children adapted to hot climate and had higher thermal comfort tolerance than adults. Preliminary findings suggest that it is unnecessary to use air conditioning system all year round. These findings could help and encourage architects and engineers to deliver schools reaching acceptable comfort levels without the need of air conditioning system

    Oncological safety of stromal vascular fraction enriched fat grafting in two-stage breast reconstruction after nipple sparing mastectomy: long-term results of a prospective study

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    OBJECTIVE: Autologous fat transfer (AFT) is commonly used to treat implant palpability and prevent fibrosis and thinning in mastectomy skin flaps. A major limit to this procedure is volume retention over time, leading to the introduction of fat enrichment with stromal vascular fraction (SVF+AFT). Oncological concerns have been raised over the injection of an increased concentration of progenitors cells (ASCs) in the SVF. The aim of the study is to evaluate the long-term cancer recurrence risk of SVF+AFT cases compared to AFT, in patients undergoing Nipple Sparing Mastectomy (NSM). PATIENTS AND METHODS: A prospective study was designed to compare three groups of patients undergoing NSM followed by SVF+AFT, AFT or none (control group), after a two-stage breast reconstruction. Patients were strictly followed-up for at least 5-years from the second stage reconstructive procedure. Loco-regional and systemic recurrence rate were evaluated over time as the primary outcome. Logistic regression was used to investigate which factors were associated with recurrence events and independent variables of interest were: surgical technique, age above 50 years old, lympho-vascular invasion, oncological stage, adjuvant or neoadjuvant chemotherapy, adjuvant radiotherapy and adjuvant hormone therapy. RESULTS: 41 women were included in G1 (SVF+AFT), 64 in G2 (AFT), and 64 in G3 (control group). Loco-regional recurrence rate was 2.4% for G1, 4.7% for G2, and 1.6% for G3. Systemic recurrence was 7.3%, 3.1%, and 3.1%, respectively. Among the variables included, there were no significant risk factors influencing a recurrence event, either loco-regional or systemic. In particular, SVF+AFT (G1) did not increase the oncological recurrence. CONCLUSIONS: Our data suggest that both centrifuged and SVF-enhanced fat transfer have a similar safety level in comparison to patients who did not undergo fat grafting in breast reconstruction after NSM
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