Do people perceive benefits in the use of social prescribing to address loneliness and/or social isolation? A qualitative meta-synthesis of the literature.

Social prescribing is a means by which clinical services can link individuals who have psychological, social and/or practical needs with non-clinical services within their local community. There is a lack of empirical evidence investigating whether social prescribing helps such individuals and which interventions are the most effective and accepted by them to address their loneliness. This meta-synthesis aimed to synthesise findings from qualitative studies exploring experiences of people (of any age) who participated in any social prescribing intervention aimed at loneliness and/or social isolation to ascertain whether they felt it helped address loneliness/isolation and the potential mechanisms by which this might occur. We conducted a systematic search of 5 electronic databases and 4 other databases that would yield grey literature in April 2021 to identify qualitative articles on this topic written in English or French. We assessed the quality of the included studies using recognised tools, and synthesised findings using the approach of thematic analysis. We identified 19 records analysed (e.g. journal articles) from 18 studies meeting inclusion criteria. Our analysis identified three themes: (1) increased sense of wellbeing (with six subthemes), (2) factors that engendered an ongoing desire to connect with others, and (3) perceived drawbacks of social prescribing. These themes illustrate the benefits and difficulties people perceive in social prescribing programmes addressing loneliness and social isolation, with an overall balance of more benefits than drawbacks in social prescribing participation. However, given the unhelpful aspects of social prescribing identified by some participants, greater thought should be given to potential harms. Moreover, further qualitative and quantitative research is needed to better understand mechanisms and effectiveness, and how different components of social prescribing might be best matched to individual participants.

Spectral anomalies and Gouy rotation around the singularity of ultrashort vortex pulses.

Spectral anomalies of femtosecond pulses with orbital angular momentum were studied in the vicinity of singularities. Bessel-Gauss (BG) beams were generated with mode-locked Ti:sapphire oscillators and dispersion-compensated diffractive axicons acting as spiral phase plates (SPPs). High-resolution two-dimensional spectral mapping was performed with a scanning fiber probe. Progressive rotation of the most pronounced features, known as "spectral eyes", in the maps of spectral moments was found at increasing propagation distance. The phenomenon is explained by a wavelength-dependent Gouy phase shift of interfering spectral components in the twisted wavefront. Spatial "spectral switching" was detected for few-cycle pulses. Possible improvements of selectivity are proposed.

Probing the Nodal Structure of Landau Level Wave Functions in Real Space.

The inversion layer of p-InSb(110) obtained by Cs adsorption of 1.8% of a monolayer is used to probe the Landau level wave functions within smooth potential valleys by scanning tunneling spectroscopy at 14 T. The nodal structure becomes apparent as a double peak structure of each spin polarized first Landau level, while the zeroth Landau level exhibits a single peak per spin level only. The real space data show single rings of the valley-confined drift states for the zeroth Landau level and double rings for the first Landau level. The result is reproduced by a recursive Green function algorithm using the potential landscape obtained experimentally. We show that the result is generic by comparing the local density of states from the Green function algorithm with results from a well-controlled analytic model based on the guiding center approach.

Patient radiation protection covers for head CT scans - a clinical evaluation of their effectiveness.

PURPOSE: Although the use of thyroid shields for patients for head CT examinations is reasonable and even required by German regulations, so far available shields are often not used due to difficult applicability. New shields that are easier to use and therefore may gain wider acceptance and more frequent use are now available. In this work two new patient shields are investigated regarding their dose reduction effectiveness and applicability and compared to a thyroid/sternum shield typically used as a part of personal protective equipment. MATERIALS AND METHODS: The reduction of organ doses for thyroid, sternum and mamma were measured with thermoluminescence detectors in an anthropomorphic female phantom. Additionally, the influence of the length or position of the overview scan at the beginning of the CT examination was taken into account. RESULTS: Depending on the patient shield, a reduction of the organ doses for thyroid of 5 - 24 %, for sternum of 25 - 48 % and for mamma of 25 - 70 % could be found. A shift of 25 mm in the cranial direction for the overview scan resulted in a reduction of these organ doses of 12 - 15 %. CONCLUSION: Patient shields for cranial CT examinations provide a considerable dose reduction. New models are easily applied and no decrease in image quality through reconstruction artifacts could be found. Therefore, it is advised to use shields which are applied upon the patient without the need to be wrapped around the neck and the overview scan should be positioned as close as possible to the examined region. KEY POINTS: • New shields provide a compromise between usability and radiation protection.• Patient shields reduce organ doses even when not directly exposed.• The overview scan contributes considerably to out of field organ doses.• Shielding factors are greatly influenced by the positioning of the examination field.

Accelerating cardiac bidomain simulations using graphics processing units.

Anatomically realistic and biophysically detailed multiscale computer models of the heart are playing an increasingly important role in advancing our understanding of integrated cardiac function in health and disease. Such detailed simulations, however, are computationally vastly demanding, which is a limiting factor for a wider adoption of in-silico modeling. While current trends in high-performance computing (HPC) hardware promise to alleviate this problem, exploiting the potential of such architectures remains challenging since strongly scalable algorithms are necessitated to reduce execution times. Alternatively, acceleration technologies such as graphics processing units (GPUs) are being considered. While the potential of GPUs has been demonstrated in various applications, benefits in the context of bidomain simulations where large sparse linear systems have to be solved in parallel with advanced numerical techniques are less clear. In this study, the feasibility of multi-GPU bidomain simulations is demonstrated by running strong scalability benchmarks using a state-of-the-art model of rabbit ventricles. The model is spatially discretized using the finite element methods (FEM) on fully unstructured grids. The GPU code is directly derived from a large pre-existing code, the Cardiac Arrhythmia Research Package (CARP), with very minor perturbation of the code base. Overall, bidomain simulations were sped up by a factor of 11.8 to 16.3 in benchmarks running on 6-20 GPUs compared to the same number of CPU cores. To match the fastest GPU simulation which engaged 20 GPUs, 476 CPU cores were required on a national supercomputing facility.

Wave-function mapping of graphene quantum dots with soft confinement.

Using low-temperature scanning tunneling spectroscopy, we map the local density of states of graphene quantum dots supported on Ir(111). Because of a band gap in the projected Ir band structure around the graphene K point, the electronic properties of the QDs are dominantly graphenelike. Indeed, we compare the results favorably with tight binding calculations on the honeycomb lattice based on parameters derived from density functional theory. We find that the interaction with the substrate near the edge of the island gradually opens a gap in the Dirac cone, which implies soft-wall confinement. Interestingly, this confinement results in highly symmetric wave functions. Further influences of the substrate are given by the known moiré potential and a 10% penetration of an Ir surface resonance into the graphene layer.

Effect of sugammadex or neostigmine neuromuscular block reversal on bispectral index monitoring of propofol/remifentanil anaesthesia.

BACKGROUND: Sugammadex is a modified γ-cyclodextrin with a novel mechanism of action for reversing the steroidal neuromuscular blocking agent rocuronium. Bispectral index (BIS) is an EEG-derived measure which can be sensitive to frontal electromyographic (EMG) artifacts. We compared BIS values before and after sugammadex or neostigmine neuromuscular block (NMB) reversal in patients with or without high EMG activity. METHODS: During stable propofol/remifentanil anaesthesia and rocuronium-induced block, 48 patients were randomly allocated to receive sugammadex 4 mg kg(-1) or neostigmine 50 µg kg(-1)/glycopyrrolate 10 µg kg(-1), 10 min after the end of surgery. RESULTS: Five minutes after sugammadex administration, mean BIS 50.1 (10.3) increased (P=0.018) to 61.7 (7.9) in 11 patients with high EMG activity. In contrast, BIS 49.3 (4.9) remained at 51.9 (5.4) in 13 patients who had no EMG activity. Fifteen minutes after neostigmine administration, mean BIS 51.9 (8.1) increased (P=0.007) to 63.9 (8.1) in 13 patients who had reappearance of muscle activity. However, in 11 patients who had no EMG activity, BIS 52.3 (7.4) remained at 53.3 (6.8). There was no significant difference between the sugammadex and neostigmine groups over time. CONCLUSIONS: We have shown that reversal of NMB with sugammadex or neostigmine increased BIS values dependent on the presence of EMG activity. Thus, the effect of muscle activity reappearance during rocuronium NMB reversal spuriously increasing the BIS value should be taken into consideration when relying on BIS monitoring for evaluating propofol/remifentanil recovery.

SU-E-I-42: Measurement of X-Ray Beam Width and Geometric Efficiency in MDCT Using Radiochromic Films.

PURPOSE: The purpose of this work was to measure the x-ray beam width and geometric efficiency (GE) of a multi detector computed tomography scanner (MDCT) for different beam collimations using radiochromic films. In MDCT, the primary beam width extends the nominal beam collimation to irradiate the active detector elements uniformly (called 'over-beaming') which contributes to increased radiation dose to the patient compared to single detector CT. Therefore, the precise determination of the primary beam width and GE is of value for any CT dose calculation using Monte Carlo or analytical methods. METHODS: Single axial dose profiles free in air were measured for 6 different beam collimations nT for a Siemens SOMATOM Sensation 64 Scanner with Gafchromic XR-QA2 films. The films were calibrated relative to the measured charge of a PTW semiflex ionization chamber (type: 31010) for a single rotation in the CT scanner at the largest available beam collimation of 28.8 mm. The beam energy for all measurements in this work was set to 120 kVp. For every measured dose profile and beam collimation the GEin-air and the full-width-at-half- maximum value (FWHM) as a value for the x-ray beam width was determined. Over-beaming factors FWHM / nT were calculated accordingly. RESULTS: For MDCT beam collimations from 7.2 (12×0.6 mm) to 28.8 (24×1.2 mm) the geometric efficiency was between 58 and 85 %. The over- beaming factor ranged from 1.43 to 1.11. For beam collimations of 1×5 mm and 1×10 mm the GE was 77 % and 84 % respectively. The over-beaming factors were close to 1, as expected. CONCLUSIONS: This work has shown that radiochromic films can be used for accurate x-ray beam width and geometric efficiency measurements due to their high spatial resolution. The measured free-in-air geometric efficiency and the over-beaming factor depend strongly on beam collimation.

SU-E-I-106: Description of Energy Dose Deposition Kernel for the Diagnostic Beam.

PURPOSE: Over the recent years, the employment of kV x-rays as a diagnostic tool into clinical routine has resulted in a significant increase in the patient's exposure to ionizing radiation. The accurate determination of the absorbed dose to patients during diagnosis is therefore necessary to avoid unnecessary exposure to the patient. This study presents an analytical model of the energy deposition kernel for the monoenergetic and polyenergetic kV beams for the fast calculation of dose in radiography. METHODS: The analytical model is based on the pencil beam kernels derived from Monte Carlo simulations. DOSXYZnrc code from the EGSnrc family was employed to simulate the pencil beam of 0.1 cm width for 80, 100 and 120 keV mono-energetic and polyenergetic beams. The lateral dose profiles were calculated at different depths within a homogenous water phantom of size 50×50×50 cm3 . The evaluated dose profiles showed a high amplitude primary component at the central axis and a long range low amplitude scatter component spanning a considerable distance from the central axis. The profiles were fitted analytically with a triple exponential decay function with an offset. All coefficients of the exponential function were further fitted with appropriate analytical functions to represent their behavior relative to depth and photon energy. The accuracy of the obtained kernel was checked by the convolution of a rectangular fluence profile and comparing the calculated dose distribution with the Monte Carlo simulated dose profiles for 2×2 cm2 field size. RESULTS AND CONCLUSION: In a homogeneous phantom, the comparisons of the convolution method and Monte Carlo simulations showed sufficient agreement except for largest depths (deviation approx. 15%). Future developments will focus on an implementation of the method for dose calculation in the patient.

SU-E-I-107: Suitability of Various Radiation Detectors Used in Radiation Therapy for X-Ray Dosimetry in Computed Tomography.

PURPOSE: Assessment of suitability for X-ray dosimetry in computed tomography of various ionization chambers, diodes and two-dimensional detector arrays primarily used in radiation therapy. METHODS: An Oldelft X-ray simulation unit was used to irradiate PTW 60008, 60012 dosimetry diodes, PTW 23332, 31013, 31010, 31006 axial symmetrical ionization chambers, PTW 23343, 34001 plane parallel ionization chambers and PTW Starcheck and 2D-Array seven29 as well as a prototype Farmer chamber with a copper wall. Peak potential was varied from 50 kV up to 125 kV and beam qualities were quantified through half-value-layer measurements. Energy response was investigated free in air as well as in 2 cm depth in a solid water phantom and refers to a manufacturer calibrated PTW 60004 diode for kV-dosimetry. RESULTS: The thimble ionization chambers PTW 31010, 31013, the uncapsuled diode PTW 60012 and the PTW 2D-Array seven29 exhibit an energy response deviation in the investigated energy region of approximately 10% or lower thus proving good usability in X-ray dosimetry if higher spatial resolution is needed or rotational irradiations occur. CONCLUSIONS: It could be shown that in radiation therapy routinely used detectors are usable in a much lower energy region. The rotational symmetry is of advantage in computed tomography dosimetry and enables dose profile as well as point dose measurements in a suitable phantom for estimation of organ doses. Additional the PTW 2D-Array seven29 can give a quick overview of radiation fields in non-rotating tasks.

Probing electron-electron interaction in quantum Hall systems with scanning tunneling spectroscopy.

Using low-temperature scanning tunneling spectroscopy applied to the Cs-induced two-dimensional electron system (2DES) on p-type InSb(110), we probe electron-electron interaction effects in the quantum Hall regime. The 2DES is decoupled from bulk states and exhibits spreading resistance within the insulating quantum Hall phases. In quantitative agreement with calculations we find an exchange enhancement of the spin splitting. Moreover, we observe that both the spatially averaged as well as the local density of states feature a characteristic Coulomb gap at the Fermi level. These results show that electron-electron interaction can be probed down to a resolution below all relevant length scales.

Bistability and oscillatory motion of natural nanomembranes appearing within monolayer graphene on silicon dioxide.

The truly two-dimensional material graphene is an ideal candidate for nanoelectromechanics due to its large strength and mobility. Here we show that graphene flakes provide natural nanomembranes of diameter down to 3 nm within its intrinsic rippling. The membranes can be lifted either reversibly or hysteretically by the tip of a scanning tunneling microscope. The clamped-membrane model including van-der-Waals and dielectric forces explains the results quantitatively. AC-fields oscillate the membranes, which might lead to a completely novel approach to controlled quantized oscillations or single atom mass detection.

Intrinsic and extrinsic corrugation of monolayer graphene deposited on SiO2.

Using scanning tunneling microscopy in an ultrahigh vacuum and atomic force microscopy, we investigate the corrugation of graphene flakes deposited by exfoliation on a Si/SiO2 (300 nm) surface. While the corrugation on SiO2 is long range with a correlation length of about 25 nm, some of the graphene monolayers exhibit an additional corrugation with a preferential wavelength of about 15 nm. A detailed analysis shows that the long-range corrugation of the substrate is also visible on graphene, but with a reduced amplitude, leading to the conclusion that the graphene is partly freely suspended between hills of the substrate. Thus, the intrinsic rippling observed previously on artificially suspended graphene can exist as well, if graphene is deposited on SiO2.

The influence of smoking on the serum level of duloxetine.

Duloxetine is a dual acting antidepressant (selective serotonin and norepinephrine reuptake inhibitor). Existing data suggest that the advisable therapeutic serum level of duloxetine ranges between 20 and 80 ng/mL. In a naturalistic setting we determined duloxetine serum levels within a steady state in a sample of depressive inpatients by high performance liquid chromatography (HPLC). The mean serum levels in 28 patients at the time of the first TDM analysis were 52.0+/-67 ng/mL. Eight of the patients were smokers and showed a considerably lower serum level of 24.3+/-18.8 ng/mL. In the further course of treatment the difference was compensated by application of higher doses in smokers. These findings suggest that smoking is associated with lower duloxetine serum levels due to an induction of CYP1A2 by polycylic hydrocarbons which are contained in tobacco smoke. Therefore in smokers higher doses of duloxetine (about 15%) seem to be necessary to reach adequate serum levels.

Thoughts of agoraphobic people during scary tasks.

The authors examined the occurrence of theoretically derived patterns of thinking in 74 agoraphobic participants as they drove alone or tolerated an enclosed place. During the increasingly scary tasks in a behavioral test hierarchy, participants responded to a periodic beep by stating aloud what they were thinking at that moment, yielding more than 1,800 tape-recorded statements. Content analyses revealed that participants were mainly preoccupied with their current anxiety (expressed in 29% of the statements) and with their self-efficacy (15%). Despite participants' mounting feelings of anxiety, fewer than 1% of their statements expressed a thought of danger or an anticipation of future anxiety or panic. The rarity of danger thoughts poses an explanatory challenge for all cognitive theories of phobia and especially for the perceived danger theory of A. T. Beck (1976) and A. T. Beck, G. Emery, and R. L. Greenberg (1985).