Initial Study on Controllable Roofing System to Tailor Building Solar Loads for Increased HVAC Efficiency

Space heating and cooling account for a significant percentage of a building's overall energy usage profile. The construction of a building's envelope is an essential component that impacts the overall heating and cooling load. For many years, flat roofs were covered with low albedo materials such as asphalt or modified bitumen, which can reach temperatures of 60 C-80 C during summer months. More recently, alternative technologies, such as "white roofs," have been put forth to mitigate the problem of unwanted thermal gain. However, these traditional roofing materials and recent innovations are passive structures and only promote seasonal benefits. This paper proposes and demonstrates the concept of a controllable reflectance roofing system that can tailor solar loads to desired heating or cooling, significantly reducing overall space heating and cooling energy requirements and costs

Excitonic recombination dynamics in shallow quantum wells

We report a comprehensive study of carrier-recombination dynamics in shallow AlxGa1-xAs/GaAs quantum wells. At low crystal temperature (2 K), the excitonic radiative recombination time is shown to be strongly enhanced in shallow quantum wells with x>0.01, consistently with a model that takes into account the thermal equilibrium between the three-dimensional exciton gas of the barrier and the two-dimensional exciton gas, which are closer in energy as x decreases. Furthermore, we demonstrate the existence of a thermally activated escape mechanism due to the low effective barrier height in these structures. The nonradiative recombination is shown to dominate the carrier dynamics for temperatures as low as 10 K for x≈0.01. Our experimental observations are analyzed using three different variational exciton calculations. In particular, we study the crossover from the two-dimensional to the three-dimensional behavior of the exciton, which occurs for x as low as 0.01 and affects mainly the oscillator strength, whereas the transition energies in shallow quantum wells can be calculated, to a large extent, using the same approximations as for conventional quantum wells. The peculiar behavior of the oscillator strength at the crossover to the weak confinement regime is obtained by expansion in a large basis

Terugblik op het ILG : kwalitatieve evaluatie van het investeringsbudget Landelijk Gebied

Deze kwalitatieve evaluatie gaat over de resultaten van vijf jaar Investeringsbudget Landelijk Gebied (ILG). Het onderzoek toont dat het ILG heeft bijgedragen aan een versterking van de provinciale regie in het landelijk gebied. Het Rijk trok zich terug, maar hield via gedetailleerde bestuursovereenkomsten met provincies en jaarlijkse voortgangsbewaking wel bemoeienis. De resultaatgerichtheid in het beleid voor het landelijk gebied is toegenomen door de afspraken over te leveren prestaties in de ILG-bestuursovereenkomsten en de vaste termijn van zeven jaar. De bundeling van rijksgelden in het ILG droeg bij aan een bundeling van geldstromen op provinciaal niveau. Dit maakte het gemakkelijker voor provincies om doelen en geldstromen te koppelen in integrale gebiedsgerichte projecten. Maatschappelijke organisaties zijn actiever betrokken geraakt bij het beleid voor het landelijk gebied. Voor burgers geldt dit nauwelijks. Het ILG beoogde ook versnelling van de uitvoering. De grondverwerving voor de Ecologische Hoofdstructuur (EHS) verliep in ongeveer hetzelfde tempo als vóór het ILG. Over het tempo van de inrichting EHS zijn geen eenduidige conclusies te trekken. De toename van het areaal particulier natuurbeheer in het ILG was vergelijkbaar met de periode daarvoor. Bij agrarisch natuurbeheer is sinds kort een voorzichtige toename te zien na een jarenlange daling. Het is niet duidelijk of de realisatie van Recreatie om de Stad in de ILG-periode sneller is gegaan. Van verbetering van de milieucondities door vernatting was nog geen sprake in de ILG-periode, omdat de verdrogingsbestrijding nog nauwelijks van de grond kwam. Het ILG is echter eerder gestopt dan de bedoeling was. Dit noopt tot voorzichtigheid bij het verbinden van conclusies aan de beschikbare cijfers

The Extent and Coverage of Current Knowledge of Connected Health: Systematic Mapping Study

Background: This paper examines the development of the Connected Health research landscape with a view on providing a historical perspective on existing Connected Health research. Connected Health has become a rapidly growing research field as our healthcare system is facing pressured to become more proactive and patient centred. Objective: We aimed to identify the extent and coverage of the current body of knowledge in Connected Health. With this, we want to identify which topics have drawn the attention of Connected health researchers, and if there are gaps or interdisciplinary opportunities for further research. Methods: We used a systematic mapping study that combines scientific contributions from research on medicine, business, computer science and engineering. We analyse the papers with seven classification criteria, publication source, publication year, research types, empirical types, contribution types research topic and the condition studied in the paper. Results: Altogether, our search resulted in 208 papers which were analysed by a multidisciplinary group of researchers. Our results indicate a slow start for Connected Health research but a more recent steady upswing since 2013. The majority of papers proposed healthcare solutions (37%) or evaluated Connected Health approaches (23%). Case studies (28%) and experiments (26%) were the most popular forms of scientific validation employed. Diabetes, cancer, multiple sclerosis, and heart conditions are among the most prevalent conditions studied. Conclusions: We conclude that Connected Health research seems to be an established field of research, which has been growing strongly during the last five years. There seems to be more focus on technology driven research with a strong contribution from medicine, but business aspects of Connected health are not as much studied

Field-induced delocalization and Zener breakdown in semiconductor superlattices

We investigate the energy spectrum and the electron dynamics of a band in a semiconductor superlattice as a function of the electric field. Linear optical spectroscopy shows that, for high fields, the well-known localization of the Bloch states is followed by a field-induced delocalization, associated with Zener breakdown. Using time-resolved measurements, we observe Bloch oscillations in a regime where they are damped by Zener breakdown

Catalytic Transformations of Alkynes via Ruthenium Vinylidene and Allenylidene Intermediates

NOTICE: This is the peer reviewed version of the following book chapter: Varela J. A., González-Rodríguez C., Saá C. (2014). Catalytic Transformations of Alkynes via Ruthenium Vinylidene and Allenylidene Intermediates. In: Dixneuf P., Bruneau C. (eds) Ruthenium in Catalysis. Topics in Organometallic Chemistry, vol 48, pp. 237-287. Springer, Cham. [doi: 10.1007/3418_2014_81]. This article may be used for non-commercial purposes in accordance with Springer Verlag Terms and Conditions for self-archiving.Vinylidenes are high-energy tautomers of terminal alkynes and they can be stabilized by coordination with transition metals. The resulting metal-vinylidene species have interesting chemical properties that make their reactivity different to that of the free and metal π-coordinated alkynes: the carbon α to the metal is electrophilic whereas the β carbon is nucleophilic. Ruthenium is one of the most commonly used transition metals to stabilize vinylidenes and the resulting species can undergo a range of useful transformations. The most remarkable transformations are the regioselective anti-Markovnikov addition of different nucleophiles to catalytic ruthenium vinylidenes and the participation of the π system of catalytic ruthenium vinylidenes in pericyclic reactions. Ruthenium vinylidenes have also been employed as precatalysts in ring closing metathesis (RCM) or ring opening metathesis polymerization (ROMP). Allenylidenes could be considered as divalent radicals derived from allenes. In a similar way to vinylidenes, allenylidenes can be stabilized by coordination with transition metals and again ruthenium is one of the most widely used metals. Metalallenylidene complexes can be easily obtained from terminal propargylic alcohols by dehydration of the initially formed metal-hydroxyvinylidenes, in which the reactivity of these metal complexes is based on the electrophilic nature of Cα and Cγ, while Cβ is nucleophilic. Catalytic processes based on nucleophilic additions and pericyclic reactions involving the π system of ruthenium allenylidenes afford interesting new structures with high selectivity and atom economy

Klimaatadaptatie in het landelijk gebied. Verkenning naar wegen voor een klimaatbestendig Nederland

Klimaatverandering werkt via hogere temperaturen, veranderingen in neerslagpatronen, veranderingen in frequentie en intensiteit van weersextremen en zeespiegelstijging door op het functioneren van het landgebruik en het watersysteem in het landelijk gebied. De doorwerking van de hierboven genoemde klimaateffecten is complex en verschilt tussen gebieden en verschillende vormen van landgebruik. Klimaatverandering bedreigt sommige functies maar biedt ook nieuwe kansen. Om deze kansen te benutten en de bedreigingen het hoofd te bieden is klimaatadaptatie nodig. Adaptatiemaatregelen in het landelijk gebied kunnen genomen worden binnen de verschillende sectoren en binnen het water-, natuur-, landbouw- en ruimtelijke ordeningsbeleid. Er is een samenhangend pakket van maatregelen nodig. Dit noemen we een integrale adaptatierichting. Deze studie onderzoekt mogelijke adaptatierichtingen voor verschillende landschapstypen; zeekleigebied, veenweide en de hoge zandgronden

Effects of extreme natural events on the provision of ecosystem services in a mountain environment : The importance of trail design in delivering system resilience and ecosystem service co-benefits

A continued supply of ecosystem services (ES) from a system depends on the resilience of that system to withstand shocks and perturbations. In many parts of the world, climate change is leading to an increased frequency of extreme weather events, potentially influencing ES provision. Our study of the effects of an intense rainfall event in Gorce National Park, Poland, shows: (1) the intense rainfall event impacted heavily on the supply of ES by limiting potential recreation opportunities and reducing erosion prevention; (2) these negative impacts were not only restricted to the period of the extreme event but persisted for up to several years, depending on the pre-event trail conditions and post-event management activities; (3) to restore the pre-event supply of ES, economic investments were required in the form of active repairs to trails, which, in Gorce National Park, were an order of magnitude higher than the costs of normal trail maintenance; and (4) when recreational trails were left to natural restoration, loss of biodiversity was observed, and recovery rates of ES (recreation opportunities and soil erosion prevention) were reduced in comparison to their pre-event state. We conclude that proper trail design and construction provides a good solution to avoid some of the negative impacts of extreme events on recreation, as well as offering co-benefits in terms of protecting biodiversity and enhancing the supply of regulating services such as erosion prevention

Influenza vaccination for immunocompromised patients: systematic review and meta-analysis from a public health policy perspective.

Immunocompromised patients are vulnerable to severe or complicated influenza infection. Vaccination is widely recommended for this group. This systematic review and meta-analysis assesses influenza vaccination for immunocompromised patients in terms of preventing influenza-like illness and laboratory confirmed influenza, serological response and adverse events