245 research outputs found

    Dielectric coupler for general purpose Q-band EPR cavity

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    Here, we report on a robust and efficient mechanism for tuning the microwave coupling of a Q-band (34 GHz), general purpose, cylindrical EPR cavity operating in the TE011 mode. This novel mechanism allows for both the adjustment of the cavity’s coupling over a wide frequency range, as well as its bandwidth from that of a high-Q cavity (about 10 MHz), to a broadband cavity (above 1 GHz). The coupling element consists of a dielectric plate fixed onto a movable waveguide short that allows for two modes of operation. In the first mode, the dielectric plate does not influence the resonance properties of the coupling iris and allows for precise, critical coupling of the high-Q cavity. In the second mode, the dielectric plate is positioned in front of the coupling iris, varying the iris’ resonance properties and allowing very strong overcoupling to be achieved. This mechanism can be generalized for other types of EPR cavities, in particular at high microwave frequencies

    The Role of Occupant Behavior in Achieving Net Zero Energy: A Demonstration Project at Fort Carson

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    This study, sponsored by the U.S. General Services Administration’s Office of Federal High-Performance Green Buildings, aimed to understand the potential for institutional and behavioral change to enhance the performance of buildings, through a demonstration project with the Department of Defense in five green buildings on the Fort Carson, Colorado, Army base. To approach this study, the research team identified specific occupant behaviors that had the potential to save energy in each building, defined strategies that might effectively support behavior change, and implemented a coordinated set of actions during a three-month intervention

    Results from EDGES High-Band: II. Constraints on Parameters of Early Galaxies

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    We use the sky-average spectrum measured by EDGES High-Band (9019090-190 MHz) to constrain parameters of early galaxies independent of the absorption feature at 7878~MHz reported by Bowman et al. (2018). These parameters represent traditional models of cosmic dawn and the epoch of reionization produced with the 21cmFAST simulation code (Mesinger & Furlanetto 2007, Mesinger et al. 2011). The parameters considered are: (1) the UV ionizing efficiency (ζ\zeta), (2) minimum halo virial temperature hosting efficient star-forming galaxies (TvirminT^{\rm min}_{\rm vir}), (3) integrated soft-band X-ray luminosity (LX<2keV/SFRL_{\rm X\,<\,2\,keV}/{\rm SFR}), and (4) minimum X-ray energy escaping the first galaxies (E0E_{0}), corresponding to a typical HI{\rm \scriptstyle I} column density for attenuation through the interstellar medium. The High-Band spectrum disfavors high values of TvirminT^{\rm min}_{\rm vir} and ζ\zeta, which correspond to signals with late absorption troughs and sharp reionization transitions. It also disfavors intermediate values of LX<2keV/SFRL_{\rm X\,<\,2\,keV}/{\rm SFR}, which produce relatively deep and narrow troughs within the band. Specifically, we rule out 39.4<log10(LX<2keV/SFR)<39.839.4<\log_{10}\left(L_{\rm X\,<\,2\,keV}/{\rm SFR}\right)<39.8 (95%95\% C.L.). We then combine the EDGES High-Band data with constraints on the electron scattering optical depth from Planck and the hydrogen neutral fraction from high-zz quasars. This produces a lower degeneracy between ζ\zeta and TvirminT^{\rm min}_{\rm vir} than that reported in Greig & Mesinger (2017a) using the Planck and quasar constraints alone. Our main result in this combined analysis is the estimate 4.54.5~log10(Tvirmin/K)\leq \log_{10}\left(T^{\rm min}_{\rm vir}/\rm K\right)\leq~5.75.7 (95%95\% C.L.). We leave for future work the evaluation of 2121~cm models using simultaneously data from EDGES Low- and High-Band.Comment: Accepted in Ap

    Machine Learning-Based Signal Degradation Models for Attenuated Underwater Optical Communication OAM Beams

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    Signal attenuation in underwater communications is a problem that degrades classification performance. Several novel CNN-based (SMART) models are developed to capture the physics of the attenuation process. One model is built and trained using automatic differentiation and another uses the radon cumulative distribution transform. These models are inserted in the classifier training pipeline. It is shown that including these attenuation models in classifier training significantly improves classification performance when the trained model is tested with environmentally attenuated images. The improved classification accuracy will be important in future OAM underwater optical communication applications

    Barriers and facilitators to physical activity: a comparative analysis of transplant athletes competing in high intensity sporting events with other transplant recipients

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    Background: There is widespread recognition that many transplant recipients struggle to become and remain physically active. However, some transplant recipients do undertake strenuous training and significant physical activity (PA) and participate in intensive sports.Aim: This study sought to understand facilitators and barriers to be physically active for Transplant Athletes (TXA) compared to a group of Dutch transplantees. This explorative mixed methods study analysed race performance and interview data from TxA who participated in cycling and/or the sprint triathlon at the World Transplant Games 2023, and compared their lived experiences in terms of barriers and facilitators of PA with those of 16 transplantees in a study from the Netherlands previously published in this journal.Methods: Using Patient and Public Involvement and engagement (PPI), race data from World Transplant Games 2023 and subsequent in-depth interviews were used from 27 TxA. A visual artefact of barriers and facilitators from the previous Dutch study was used to prompt identification and discussion of barriers and facilitators of PA. Interview data were coded by three coders.Results: Many of the barriers to PA previously reported by Dutch transplant recipients were not shared by the majority of TxA in this study. The TxA in this study reported significantly lower physical limitations, lower fear to undertake exercise, and no comorbidity issues for TxA. Furthermore, TxA perceived they received substantial social support, had the strength to do PA, and were in control of their weight.Conclusion: Several TxA reported a lack of understanding from medical and other professionals about the appropriate intensity of PA. An evidence-based framework of PA for transplant recipients and transplant athletes is needed for safe and appropriate PA

    Identification of the Chromophores in Prussian blue

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    Prussian blue was the world's first synthetic dye. Its structural, optical and magnetic properties have led to many applications in technology and medicine, and provide paradigms for understanding coordination polymers, framework materials and mixed-valence compounds. The intense red absorption of Prussian blue that characterises chemical and physical properties critical to many of these applications is now shown to arise from localised intervalence charge transfer transitions within two chromophoric variants (ligand isomers) of an idealised "dimer" fragment {(NC)5FeII}(mu-CN){FeIII(NC)3(H2O)2}. This fragment is only available in modern interpretations of the material's crystal structure, with the traditional motif {(NC)5FeII}(mu-CN){FeIII(NC)5} shown not to facilitate visible absorption. Essential to the analysis is the demonstration, obtained independently using absorption and magnetic circular dichroism spectroscopies, that spectra of Prussian blues are strongly influenced by particle size and (subsequent) light scattering. These interpretations are guided and supported by density functional theory calculations (CAM-B3LYP), supplemented by coupled cluster and Bethe-Salpeter spectral simulations, as well as electron paramagnetic resonance spectroscopy of Prussian blue and a model molecular dimeric ion [Fe2(CN)11]6-

    The primary donor of far-red photosystem II: ChlD1 or PD2?

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    Far-red light (FRL) Photosystem II (PSII) isolated from Chroococcidiopsis thermalis is studied using parallel analyses of low-temperature absorption, circular dichroism (CD) and magnetic circular dichroism (MCD) spectroscopies in conjunction with fluorescence measurements. This extends earlier studies (Nurnberg et al 2018 Science 360 (2018) 1210-1213). We confirm that the chlorophyll absorbing at 726 nm is the primary electron donor. At 1.8 K efficient photochemistry occurs when exciting at 726 nm and shorter wavelengths; but not at wavelengths longer than 726 nm. The 726 nm absorption peak exhibits a 21 ± 4 cm-1 electrochromic shift due to formation of the semiquinone anion, QA-. Modelling indicates that no other FRL pigment is located among the 6 central reaction center chlorins: PD1, PD2 ChlD1, ChlD2, PheoD1 and PheoD2. Two of these chlorins, ChlD1 and PD2, are located at a distance and orientation relative to QA- so as to account for the observed electrochromic shift. Previously, ChlD1 was taken as the most likely candidate for the primary donor based on spectroscopy, sequence analysis and mechanistic arguments. Here, a more detailed comparison of the spectroscopic data with exciton modelling of the electrochromic pattern indicates that PD2 is at least as likely as ChlD1 to be responsible for the 726 nm absorption. The correspondence in sign and magnitude of the CD observed at 726 nm with that predicted from modelling favors PD2 as the primary donor. The pros and cons of PD2 vs ChlD1 as the location of the FRL-primary donor are discussed.We recognize the support of the Australian Research Councilthrough grants DP110104565 and DP150103137 (EK), FT140100834(NC). This work was supported by BBSRC grants BB/L011506/1 andBB/R001383/1 (AWR, AF and DN

    Conservative management versus open reduction and internal fixation for mid-shaft clavicle fractures in adults - The Clavicle Trial: Study protocol for a multicentre randomized controlled trial

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    Background: Clavicle fractures account for around 4% of all fractures and up to 44% of fractures of the shoulder girdle. Fractures of the middle third (or mid-shaft) account for approximately 80% of all clavicle fractures. Management of this group of fractures is often challenging and the outcome can be unsatisfactory. In particular it is not clear whether surgery produces better outcomes than non-surgical management. Currently there is much variation in the use of surgery and a lack of good quality evidence to inform our decision.Methods/Design: We aim to undertake a multicentre randomised controlled trial evaluating the effectiveness and safety of conservative management versus open reduction and internal fixation for displaced mid-shaft clavicle fractures in adults. Surgical treatment will be performed using the Acumed clavicle fixation system. Conservative management will consist of immobilisation in a sling at the side in internal rotation for 6 weeks or until clinical or radiological union. We aim to recruit 300 patients. These patients will be followed-up for at least 9 months. The primary endpoint will be the rate of non-union at 3 months following treatment. Secondary endpoints will be limb function measured using the Constant-Murley Score and the Disabilities of the Arm, Shoulder and Hand (DASH) Score at 3 and 9 months post-operatively.Discussion: This article presents the protocol for a multicentre randomised controlled trial. It gives extensive details of, and the basis for, the chosen methods, and describes the key measures taken to avoid bias and to ensure validity.Trial Registration: United Kingdom Clinical Research Network ID: 8665. The date of registration of the trial is 07/09/2006. The date the first patient was recruited is 18/12/2007. © 2011 Longo et al; licensee BioMed Central Ltd
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