473 research outputs found

    Biohiilipohjaiset suodatinratkaisut

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    Tiivistelmä. Biohiilen käyttöä epäpuhtauksien poistossa voidaan pitää erittäin potentiaalisena vaihtoehtona muita suodatinratkaisuja hyödyntäville kohteille. Se soveltuu erinomaisesti myös valuma-alueille estämään tulvia suuren absorptiokyvyn takia. Jäte- ja sivuvirroista valmistettava biohiili on kustannustehokasta, uusiutuvaa ja sille on useita erilaisia käyttömahdollisuuksia. Biomassapohjaisia jäte- ja sivuvirtoja on saatavilla runsaasti maa- ja metsätaloudesta sekä jätehuollosta. Niiden hyödyntämisellä edistetään kiertotaloutta ja vähennetään ympäristön kuormitusta. Pitkäkestoisten suodatuskokeiden puutteen takia biohiilen säilyvyydestä suodatinmateriaalina ei ole saatavilla varmaa tietoa. Biohiilisuodattimet tarvitsevat vielä paljon kehitystä ja tietoa siitä, miten ehkäistään oikovirtaus, tukkeutuminen ja tiheä suodatinmassan vaihto. Toteutettuja hankkeita on haastavaa verrata toisiinsa vaihtelevien olosuhteitten takia. Hankkeiden suodatinratkaisut poikkeavat toisistaan koon, rakenteen, puhdistettavan veden ja suodatinmassan osalta. Seuranta ei myöskään ole aina säännöllistä, jolloin ongelmien ennustaminen ja havaitseminen vaikeutuu. Tutkielmassa tarkastelluissa hankkeissa todettiin biohiilen poistavan tehokkaasti mikromuoveja, kokonaisfosforia ja typpeä. Metalleista hyviä tuloksia saatiin alumiinille, raudalle ja fosforille. Mikromuovien pidättyminen oli 425–500 µm:n muovipartikkeleille eri menetelmien keskiarvona 99,6 prosenttia. Myös pienempien muovipartikkeleiden pidättyminen oli lähes täydellistä. Purkupuuhiilellä saavutettiin 50 prosentin kokonaisfosforin reduktio. Kokonaistypen reduktio oli biohiilimateriaalista riippuen 35–50 prosenttia. Parhaimpiin tuloksiin päästiin liete-, koivu- ja kuusihiilillä. Orgaanisen aineksen ja COD reduktiota havaittiin myös. Ne jäivät kuitenkin verrattain alhaisiksi (< 30 prosenttia). Tutkimusta parhaiten soveltuvista materiaaleista ja toimivista pitkäaikaisista suodatinrakenteista tarvitaan edelleen paljon. Suodatinmateriaalina käytetylle biohiilelle on kuitenkin löydetty hyviä jatkokäyttömahdollisuuksia. Epäpuhtauksia sitonut biohiili on ravinnerikasta ja siten erinomainen materiaali käytettäväksi maanparannuksessa kasvualustana. Poistetuista epäpuhtauksista riippuen, biohiili voidaan käyttää myös energiatuotannossa

    Emittance growth in linear induction accelerators

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    The Dual-Axis Radiographic Hydrotest (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. On the DARHT Axis-II LIA we measure an emittance higher than predicted by theoretical simulations, and even though this axis produces sub-millimeter source spots, we are exploring ways to improve the emittance. Some of the possible causes for the discrepancy have been investigated using particle-in-cell (PIC) codes, although most of these are discounted based on beam measurements. The most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo.Comment: 20th Int. Conf. on High-Power Particle Beams, Washington, DC, May, 201

    Millennial-Scale Climate Variability during the Last Glacial Period in the Tropical Andes

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    Millennial-scale climate variation during the Last Glacial period is evident in many locations worldwide, but it is unclear if such variation occurred in the interior of tropical South America, and, if so, how the low-latitude variation was related to its high-latitude counterpart. A high-resolution record, derived from the deep drilling of sediments on the floor of Lake Titicaca in the southern tropical Andes, is presented that shows clear evidence of millennial-scale climate variation between ~60 and 20 ka BP. This variation is manifested by alternations of two interbedded sedimentary units. The two units have distinctive sedimentary, geochemical, and paleobiotic properties that are controlled by the relative abundance of terrigenous or nearshore components versus pelagic components. The sediments of more terrigenous or nearshore nature likely were deposited during regionally wetter climates when river transport of water and sediment was higher, whereas the sediments of more pelagic character were deposited during somewhat drier climates regionally. The majority of the wet periods inferred from the Lake Titicaca sediment record are correlated with the cold events in the Greenland ice cores and North Atlantic sediment cores, indicating that increased intensity of the South American summer monsoon was part of near-global scale climate excursions

    Mortality following Campylobacter infection: a registry-based linkage study

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    BACKGROUND: Campylobacteriosis is one of the most commonly identified causes of bacterial diarrheal disease and a common cause of gastroenteritis in travellers from developed nations. Despite the widespread occurrence, there is little information on Campylobacter mortality. METHODS: Mortality among a cohort of Campylobacter cases were compared with the general population 0–1, 1–3, 3–12 and more than 12 month after the onset of the illness. The cases were sub-grouped according to if they had been infected domestically or abroad. RESULTS: The standardized mortality ratio for cases infected domestically was 2.9 (95% CI: 1.9–4.0) within the first month following the illness. The risk then gradually diminished and approached 1.0 after one year or more have passed since the illness. This initial excess risk was not attributable to any particular age group (such as the oldest). In contrast, for those infected abroad, a lower standardized mortality ratio 0.3 (95% CI: 0.04–0.8) was shown for the first month after diagnosis compared to what would be expected in the general population. CONCLUSION: Infection with Campylobacter is associated with an increased short-term risk of death among those who were infected domestically. On the contrary, for those infected abroad a lower than expected risk of death was evident. We suggest that the explanation behind this is a "healthy traveler effect" among imported cases, and effects of a more frail than average population among domestic cases

    Hearing the voices of older adult patients: processes and findings to inform health services research

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    Background Clinical academic research and service improvement is planned using Patient and Public Involvement and Engagement (PPIE) but older PPIE participants are consulted less often due to the perception that they are vulnerable or hard to engage. Objectives To consult frail older adults about a recently adopted service, discharge to assess (D2A), and to prioritise services improvements and research topics associated with the design and delivery of discharge from hospital. To use successive PPIE processes to enable a permanent PPIE panel to be established. Participants Following guidance from an established hospital PPI panel 27 older adult participants were recruited. Participants from Black, Asian and Minority Ethnic (BAME) communities, affluent and non-affluent areas and varied social circumstances were included. Methods Focus groups and individual interviews were conducted in participants own homes or nearby social venues. Results Priorities for discharge included remaining independent despite often feeling lonely at home; to remain in hospital if needed; and for services to ensure effective communication with families. The main research priority identified was facilitating independence, whilst establishing a permanent PPIE panel involving older adults was viewed favourably. Conclusions Taking a structured approach to PPIE enabled varied older peoples’ voices to express their priorities and concerns into early discharge from hospital, as well as enabling the development of health services research into hospital discharge planning and management. Older people as participants identified research priorities after reflecting on their experiences. Listening and reflection enabled researchers to develop a new “Community PPIE Elders Panel” to create an enduring PPIE infrastructure for frail older housebound people to engage in research design, development and dissemination

    Implementing a public web based GIS service for feedback of surveillance data on communicable diseases in Sweden

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    BACKGROUND: Surveillance data allow for analysis, providing public health officials and policy-makers with a basis for long-term priorities and timely information on possible outbreaks for rapid response (data for action). In this article we describe the considerations and technology behind a newly introduced public web tool in Sweden for easy retrieval of county and national surveillance data on communicable diseases. METHODS: The web service was designed to automatically present updated surveillance statistics of some 50 statutory notifiable diseases notified to the Swedish Institute for Infectious Disease Control (SMI). The surveillance data is based on clinical notifications from the physician having treated the patient and laboratory notifications, merged into cases using a unique personal identification number issued to all Swedish residents. The web service use notification data from 1997 onwards, stored in a relational database at the SMI. RESULTS: The web service presents surveillance data to the user in various ways; tabulated data containing yearly and monthly disease data per county, age and sex distribution, interactive maps illustrating the total number of cases and the incidence per county and time period, graphs showing the total number of cases per week and graphs illustrating trends in the disease data. The system design encompasses the database (storing the data), the web server (holding the web service) and an in-the-middle computer (to ensure good security standards). CONCLUSIONS: The web service has provided the health community, the media, and the public with easy access to both timely and detailed surveillance data presented in various forms. Since it was introduced in May 2003, the system has been accessed more than 1,000,000 times, by more than 10,000 different viewers (over 12.600 unique IP-numbers)

    Seasonality and the effects of weather on Campylobacter infections

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    Background Campylobacteriosis is a major public health concern. The weather factors that influence spatial and seasonal distributions are not fully understood. Methods To investigate the impacts of temperature and rainfall on Campylobacter infections in England and Wales, cases of Campylobacter were linked to local temperature and rainfall at laboratory postcodes in the 30 days before the specimen date. Methods for investigation included a comparative conditional incidence, wavelet, clustering, and time series analyses. Results The increase of Campylobacter infections in the late spring was significantly linked to temperature two weeks before, with an increase in conditional incidence of 0.175 cases per 100,000 per week for weeks 17 to 24; the relationship to temperature was not linear. Generalized structural time series model revealed that changes in temperature accounted for 33.3% of the expected cases of Campylobacteriosis, with an indication of the direction and relevant temperature range. Wavelet analysis showed a strong annual cycle with additional harmonics at four and six months. Cluster analysis showed three clusters of seasonality with geographic similarities representing metropolitan, rural, and other areas. Conclusions The association of Campylobacteriosis with temperature is likely to be indirect. High-resolution spatial temporal linkage of weather parameters and cases is important in improving weather associations with infectious diseases. The primary driver of Campylobacter incidence remains to be determined; other avenues, such as insect contamination of chicken flocks through poor biosecurity should be explored
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