From movement to motivation: a proposed framework to understand the antidepressant effect of exercise.

Depression is the leading cause of disability worldwide, exerting a profound negative impact on quality of life in those who experience it. Depression is associated with disruptions to several closely related neural and cognitive processes, including dopamine transmission, fronto-striatal brain activity and connectivity, reward processing and motivation. Physical activity, especially aerobic exercise, reduces depressive symptoms, but the mechanisms driving its antidepressant effects are poorly understood. Here we propose a novel hypothesis for understanding the antidepressant effects of exercise, centred on motivation, across different levels of explanation. There is robust evidence that aerobic exercise decreases systemic inflammation. Inflammation is known to reduce dopamine transmission, which in turn is strongly implicated in effort-based decision making for reward. Drawing on a broad range of research in humans and animals, we propose that by reducing inflammation and boosting dopamine transmission, with consequent effects on effort-based decision making for reward, exercise initially specifically improves 'interest-activity' symptoms of depression-namely anhedonia, fatigue and subjective cognitive impairment - by increasing propensity to exert effort. Extending this framework to the topic of cognitive control, we explain how cognitive impairment in depression may also be conceptualised through an effort-based decision-making framework, which may help to explain the impact of exercise on cognitive impairment. Understanding the mechanisms underlying the antidepressant effects of exercise could inform the development of novel intervention strategies, in particular personalised interventions and boost social prescribing.

Terahertz near-field microscopy of metallic circular split ring resonators with graphene in the gap.

Optical resonators are fundamental building blocks of photonic systems, enabling meta-surfaces, sensors, and transmission filters to be developed for a range of applications. Sub-wavelength size (< λ/10) resonators, including planar split-ring resonators, are at the forefront of research owing to their potential for light manipulation, sensing applications and for exploring fundamental light-matter coupling phenomena. Near-field microscopy has emerged as a valuable tool for mode imaging in sub-wavelength size terahertz (THz) frequency resonators, essential for emerging THz devices (e.g. negative index materials, magnetic mirrors, filters) and enhanced light-matter interaction phenomena. Here, we probe coherently the localized field supported by circular split ring resonators with single layer graphene (SLG) embedded in the resonator gap, by means of scattering-type scanning near-field optical microscopy (s-SNOM), using either a single-mode or a frequency comb THz quantum cascade laser (QCL), in a detectorless configuration, via self-mixing interferometry. We demonstrate deep sub-wavelength mapping of the field distribution associated with in-plane resonator modes resolving both amplitude and phase of the supported modes, and unveiling resonant electric field enhancement in SLG, key for high harmonic generation.

2D Time-Domain Spectroscopy for Determination of Energy and Momentum Relaxation Rates of Hydrogen-Like Donor States in Germanium.

We present measurements of the coherence times of excited states of hydrogen-like arsenic impurities in germanium (Ge:As) using a table-top two-dimensional time-domain spectroscopy (2D-TDS) system. We show that this laboratory system is capable of resolving the coherence lifetimes of atomic-like excited levels of impurity centers in semiconductors, such as those used in solid-state quantum information technologies, on a subpicosecond time scale. By fitting the coherent nonlinear response of the system with the known intracenter transition frequencies, we are able to monitor coherent population transfer and decay of the transitions from the 2p0 and 2p± states for different low excitation pulse fields. Furthermore, by examining the off-diagonal resonances in the 2D frequency-domain map, we are able to identify coherences between excited electronic states that are not visible via conventional single-frequency pump-probe or Hahn-echo measurements.

Contemporary outcomes of left thoraco-abdominal esophagectomy due to cancer in the esophagus or gastroesophageal junction, a multicenter cohort study.

Surgery for cancer of the esophagus or gastro-esophageal junction can be performed with a variety of minimally invasive and open approaches. The left thoracoabdominal esophagectomy (LTE) is an open technique that gives an opportunity to operate in the chest and abdomen with excellent exposure of the gastro-esophageal junction through a single incision, and there is currently no equivalent minimally invasive technique available. The aim of this multi-institutional review was to study a large contemporary international study cohort of patients treated with LTE. An international multicenter cohort study was performed including all patients treated with LTE at six high-volume centers for gastro-esophageal cancer surgery between 2012 and 2022. Patient data were prospectively collected in each participating centers' institutional database. Information about patient, tumor, and treatment details were collected. The study cohort included a total of 793 patients treated with LTE during the study period. The most frequently observed complications were pneumonia in 185/727 (25.5%) patients and atrial fibrillation in 91/727 (12.5%). Anastomotic leak occurred in 35/727 (4.8%) patients; no patient suffered from conduit necrosis. Thirty-day mortality occurred in 15/785 (1.9%) patients and 90-day mortality in 39/785 (5.0%) patients. Factors with statistically significant association with survival were American Society for Anesthesiologists-score, tumor location, tumor stage, and tumor free resection margins. Neoadjuvant therapy was not associated with increased survival compared to surgery alone but neoadjuvant chemoradiotherapy compared to neoadjuvant chemotherapy showed statistically significant improved survival with hazard ratio 0.60 (95% confidence intervals:0.44-0.80, P = 0.001) in a multivariable adjusted model. This study demonstrates that LTE can be applied in selected patients with results that are comparable to other large studies of open and minimally invasive surgery for esophageal or gastro-esophageal cancer at high-volume centers.

Terahertz in vivo imaging of human skin: Toward detection of abnormal skin pathologies.

Terahertz (THz) imaging has long held promise for skin cancer detection but has been hampered by the lack of practical technological implementation. In this article, we introduce a technique for discriminating several skin pathologies using a coherent THz confocal system based on a THz quantum cascade laser. High resolution in vivo THz images (with diffraction limited to the order of 100 µm) of several different lesion types were acquired and compared against one another using the amplitude and phase values. Our system successfully separated pathologies using a combination of phase and amplitude information and their respective surface textures. The large scan field (50 × 40 mm) of the system allows macroscopic visualization of several skin lesions in a single frame. Utilizing THz imaging for dermatological assessment of skin lesions offers substantial additional diagnostic value for clinicians. THz images contain information complementary to the information contained in the conventional digital images.

Near-field detection of gate-tunable anisotropic plasmon polaritons in black phosphorus at terahertz frequencies.

Polaritons in two-dimensional layered crystals offer an effective solution to confine, enhance and manipulate terahertz (THz) frequency electromagnetic waves at the nanoscale. Recently, strong THz field confinement has been achieved in a graphene-insulator-metal structure, exploiting THz plasmon polaritons (PPs) with strongly reduced wavelength (λp ≈ λ0/66) compared to the photon wavelength λ0. However, graphene PPs propagate isotropically, complicating the directional control of the THz field, which, on the contrary, can be achieved exploiting anisotropic layered crystals, such as orthorhombic black-phosphorus. Here, we detect PPs, at THz frequencies, in hBN-encapsulated black phosphorus field effect transistors through THz near-field photocurrent nanoscopy. The real-space mapping of the thermoelectrical near-field photocurrents reveals deeply sub-wavelength THz PPs (λp ≈ λ0/76), with dispersion tunable by electrostatic control of the carrier density. The in-plane anisotropy of the dielectric response results into anisotropic polariton propagation along the armchair and zigzag crystallographic axes of black-phosphorus. The achieved directional subwavelength light confinement makes this material system a versatile platform for sensing and quantum technology based on nonlinear optics.

Compact terahertz harmonic generation in the Reststrahlenband using a graphene-embedded metallic split ring resonator array.

Harmonic generation is a result of a strong non-linear interaction between light and matter. It is a key technology for optics, as it allows the conversion of optical signals to higher frequencies. Owing to its intrinsically large and electrically tunable non-linear optical response, graphene has been used for high harmonic generation but, until now, only at frequencies < 2 THz, and with high-power ultrafast table-top lasers or accelerator-based structures. Here, we demonstrate third harmonic generation at 9.63 THz by optically pumping single-layer graphene, coupled to a circular split ring resonator (CSRR) array, with a 3.21 THz frequency quantum cascade laser (QCL). Combined with the high graphene nonlinearity, the mode confinement provided by the optically-pumped CSRR enhances the pump power density as well as that at the third harmonic, permitting harmonic generation. This approach enables potential access to a frequency range (6-12 THz) where compact sources remain difficult to obtain, owing to the Reststrahlenband of typical III-V semiconductors.

Terahertz microscopy using laser feedback interferometry based on a generalised phase-stepping algorithm.

In this paper we report an improved method of coherent sensing through the use of a generalized phase-stepping algorithm to extract magnitude and phase information from interferometric fringes acquired by laser feedback interferometry (LFI). Our approach allows for significantly reduced optical sampling and acquisition times whilst also avoiding the need for fitting to complex models of lasers under optical feedback in post-processing. We investigate theoretically the applicability of this method under different levels of optical feedback, different laser parameters, and for different sampling conditions. We furthermore validate its use experimentally for LFI-based sensing using a terahertz (THz)-frequency laser in both far-field and near-field sensing configurations. Finally we demonstrate our approach for two-dimensional nanoscale imaging of the out-of-plane field supported by individual micro-resonators at THz frequencies. Our results show that fully coherent sensing can be achieved reliably with as little as 4 sampling points per imaging pixel, opening up opportunities for fast coherent sensing not only at THz frequencies but across the visible and infra-red spectrum.

Evaluating pharmacological THRomboprophylaxis in Individuals undergoing superficial endoVEnous treatment across NHS and private clinics in the UK: a multi-centre, assessor-blind, randomised controlled trial-THRIVE trial.

INTRODUCTION: Endovenous therapy is the first choice management for symptomatic varicose veins in NICE guidelines, with 56-70 000 procedures performed annually in the UK. Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), is a known complication of endovenous therapy, occurring at a rate of up to 3.4%. Despite 73% of UK practitioners administering pharmacological thromboprophylaxis to reduce VTE, no high-quality evidence supporting this practice exists. Pharmacological thromboprophylaxis may have clinical and cost benefit in preventing VTE; however, further evidence is needed. This study aims to establish whether when endovenous therapy is undertaken: a single dose or course of pharmacological thromboprophylaxis alters the risk of VTE; pharmacological thromboprophylaxis is associated with an increased rate of bleeding events; pharmacological prophylaxis is cost effective. METHODS AND ANALYSIS: A multi-centre, assessor-blind, randomised controlled trial (RCT) will recruit 6660 participants from 40 NHS and private sites across the UK. Participants will be randomised to intervention (single dose or extended course of pharmacological thromboprophylaxis plus compression) or control (compression alone). Participants will undergo a lower limb venous duplex ultrasound scan at 21-28 days post-procedure to identify asymptomatic DVT. The duplex scan will be conducted locally by blinded assessors. Participants will be contacted remotely for follow-up at 7 days and 90 days post-procedure. The primary outcome is imaging-confirmed lower limb DVT with or without symptoms or PE with symptoms within 90 days of treatment. The main analysis will be according to the intention-to-treat principle and will compare the rates of VTE at 90 days, using a repeated measures analysis of variance, adjusting for any pre-specified strongly prognostic baseline covariates using a mixed effects logistic regression. ETHICS AND DISSEMINATION: Ethical approval was granted by Brent Research Ethics Committee (22/LO/0261). Results will be disseminated in a peer-reviewed journal and presented at national and international conferences. TRIAL REGISTRATION NUMBER: ISRCTN18501431.

Bone metastases from chondroblastoma: a rare pattern of metastatic disease in an adult.

Chondroblastoma is a rare benign tumor, typically presenting in the first two decades. Systemic metastases in chondroblastoma are extremely rare and it is the rarity of these metastases which lead the World Health Organisation to re-classify this lesion from "intermediate" to "benign" in its updated classification of bone tumors in 2020. We present an unusual case of a 55 year-old male patient who presented with multiple FDG-avid bone lesions on a background of conventional chondroblastoma of the rib excised at another institution 11-years previously. Two of these lesions were also histologically-proven as conventional chondroblastoma at biopsy. This case highlights that, although rare, metastases can be seen in patients with chondroblastoma. To our knowledge, this is the only case with an unusual pattern of metastases limited to bone.

The use of the flow-void sign on MRI: highly sensitive sign in detecting bone metastases from renal cell carcinoma.

OBJECTIVE: To evaluate a range of pathologically proven malignant bone tumours, including primary bone sarcoma and metastatic bone lesions, referred to a tertiary referral centre for the presence of the flow-void sign on MR imaging. MATERIALS AND METHODS: A retrospective search was performed using the radiology information system and oncology database in our institution to identify patients over the age of 40 years referred with a solitary bone lesion. Patients with a range of pathologically proven malignant bone tumours, including primary bone tumours and metastatic bone lesions, were included in the study. MRI images were reviewed for the presence of the flow-void sign. The presence and type of the flow-void sign were correlated with lesion size. RESULTS: Two hundred and sixty-six cases were included in the study. Overall, the flow-void sign was identified in 40.9% of cases. The flow-void sign was most frequently seen in renal cell carcinoma metastasis (90.0%). The sign is highly sensitive (90%) for renal cell carcinoma metastases with a high negative predictive value (98.09%). When the flow-void sign is identified, the lesion is almost three times more likely to represent a renal cell carcinoma metastasis than any other malignant tumour in patients over the age of 40 years with a solitary bone lesion. CONCLUSION: The flow-void sign is highly sensitive for renal cell carcinoma bone metastases and could negate the need for biopsy in patients with a known history of renal cell carcinoma or in whom an occult renal cell carcinoma is subsequently identified.

Could ChatGPT Pass the UK Radiology Fellowship Examinations?

RATIONALE AND OBJECTIVES: Chat Generative Pre-trained Transformer (ChatGPT) is an artificial intelligence (AI) tool which utilises machine learning to generate original text resembling human language. AI models have recently demonstrated remarkable ability at analysing and solving problems, including passing professional examinations. We investigate the performance of ChatGPT on some of the UK radiology fellowship equivalent examination questions. METHODS: ChatGPT was asked to answer questions from question banks resembling the Fellowship of the Royal College of Radiologists (FRCR) examination. The entire physics part 1 question bank (203 5-part true/false questions) was answered by the GPT-4 model and answers recorded. 240 single best answer questions (SBAs) (representing the true length of the FRCR 2A examination) were answered by both GPT-3.5 and GPT-4 models. RESULTS: ChatGPT 4 answered 74.8% of part 1 true/false statements correctly. The spring 2023 passing mark of the part 1 examination was 75.5% and ChatGPT thus narrowly failed. In the 2A examination, ChatGPT 3.5 answered 50.8% SBAs correctly, while GPT-4 answered 74.2% correctly. The winter 2022 2A pass mark was 63.3% and thus GPT-4 clearly passed. CONCLUSION: AI models such as ChatGPT are able to answer the majority of questions in an FRCR style examination. It is reasonable to assume that further developments in AI will be more likely to succeed in comprehending and solving questions related to medicine, specifically clinical radiology. ADVANCES IN KNOWLEDGE: Our findings outline the unprecedented capabilities of AI, adding to the current relatively small body of literature on the subject, which in turn can play a role medical training, evaluation and practice. This can undoubtedly have implications for radiology.

Periostitis Ossificans: Largest Case Series with Review of Literature.

Background Periostitis ossificans (PO) are rare, benign ossifying surface lesions characterized by the centripetal ossification with osseous and soft-tissue edema. Their clinicoradiological appearances can easily mimic those of more sinister or infective surface lesion. Objective This study aimed to explore the various anatomical locations and muscle attachment at the site of PO, and evaluate the role of complementary image findings in patients presenting at our tertiary orthopaedic referral center. Patients and Methods A retrospective review of our oncology and radiology databases was undertaken to identify patients with PO reported on radiographs, magnetic resonance imaging (MRI) and computed tomography (CT) over the past 13 years (2007-2020). Patient demographics, sites of PO, muscle attachment at the site of PO, findings on complementary imaging, and clinical management outcome were documented. Results We identified 38 patients with PO with a mean age of 24 years (range: 4-66 years). Muscle attachment was seen at the site of PO in the majority of cases (89%). The majority of PO were in the lower limb and commonly seen around the attachment of quadriceps. Deltoid attachment was commonly involved in the upper limb. Conclusion Muscle attachment is commonly seen at the site of PO, which results in stripping of the periosteum resulting in soft-tissue and osseous edema and centripetal ossification.

Toward streaked collective Thomson scattering measurements on an extreme ultraviolet plasma light source.

We show through forward modeling calculations that streaked collective Thomson scattering measurements are feasible on laser-produced tin plasmas generated under conditions relevant for extreme ultraviolet lithography. Using a 532 nm probe laser beam, the feasibility of simultaneous measurements of electron plasma wave (EPW) and ion acoustic wave (IAW) spectra is investigated. Absolute photon counts for laser scattering off both waves are calculated. Probe laser electron heating and bremsstrahlung background radiation effects are accounted for. While a large spatiotemporal region can be successfully probed based on the IAW feature, only one measurement location can be accessed through the EPW as a result of the low signal to noise ratio. A portable/traveling tabletop system is proposed.

Anatomical shoulder replacements in young patients: A systematic review and meta-analysis.

Introduction: Increasing numbers of young patients receive shoulder replacements. Greater information on outcomes is needed to inform implant choice. The aim of this study was to investigate the survivorship and clinical effectiveness of hemiarthroplasty and anatomical total shoulder arthroplasty (TSA) in patients younger than 65 years. Method: A systematic review was performed of MEDLINE, EMBASE, CENTRAL, The Cochrane Database of Systematic Reviews and National Joint Registry reports. The primary outcomes were implant survival and change in perioperative shoulder scores. Results: Meta-analysis of implant survivorship was performed of six studies reporting on 416 patients. Implant survival was 86.1% (72.1,100) at 10 years for hemiarthroplasty and 82.3% (64.6,100) for TSA. 20 year survival was 80.0% for hemiarthroplasty (72.5,87.4) and 75.0% (56.9,93.1) for TSA. Ten studies were included in the meta-analysis of shoulder scores, multiple instruments were used. The standardised mean difference between pre-operative and post-operative shoulder scores was 2.15 (1.95, 2.35) for TSA at 4.2-4.9 years, and 2.72 (1.98,3.47) for hemiarthroplasty at 3.8-6 years. Conclusion: Over 80% of shoulder replacements last more than 10 years, and 75% last more than 20 years. Significant improvements in shoulder scores are shown at all time points.

Electrically Tunable Nonlinearity at 3.2 Terahertz in Single-Layer Graphene.

Graphene is a nonlinear material in the terahertz (THz) frequency range, with χ(3) ∼ 10-9 m2/V2 ∼ 15 orders of magnitude higher than that of other materials used in the THz range, such as GaAs or lithium niobate. This nonlinear behavior, combined with ultrafast dynamic for excited carriers, proved to be essential for third harmonic generation in the sub-THz and low (<2.5 THz) THz range, using moderate (60 kV/cm) fields and at room temperature. Here, we show that, for monochromatic high peak power (1.8 W) input THz signals, emitted by a quantum cascade laser, the nonlinearity can be controlled using an ionic liquid gate that tunes the graphene Fermi energy up to >1.2 eV. Pump and probe experiments reveal an intense absorption nonlinearity at 3.2 THz, with a dominant 3rd-order contribution at EF > 0.7 eV, hence opening intriguing perspectives per engineering novel architectures for light generation at frequencies > 9 THz.

A plastic scintillator and HPGe ß-γ coincidence detection system.

A network of specialist laboratories support the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) with re-measurements of radionuclide samples, including xenon gas. The measurement of four xenon fission product radionuclides (133Xe, 135Xe, 131mXe and 133mXe) can be used to detect an underground nuclear explosion. Laboratories use a range of techniques to measure the radionuclides, including beta-gamma (ß-γ) coincidence spectrometry. These highly-sensitive measurements are capable of detecting concentrations of down to 500 atoms of 133Xe in a few cm3 of xenon. In some detector systems, detection of the metastable isomers (131mXe and 133mXe) can be more challenging due to interferences between the signatures of different radionuclides. Recent work has shown that using high-purity Germanium (HPGe) high-resolution gamma detectors, these interferences can be reduced, lowering the dependence of the detection limits on radionuclide sample isotopic composition. One downside of these detectors is the reduction in detection efficiency, which impacts the overall detection sensitivity; so assessing different detector systems is a priority for radionuclide laboratories. This work presents a coincidence detector system comprising of a plastic scintillator gas cell and a large-crystal high-purity germanium detector. The energy resolution, coincidence detection efficiency, MDA and interference factors are determined from measurements of synthetic radioxenon gas samples.

Quantitative increases of extracellular vesicles in prolonged cold storage of platelets increases the potential to enhance fibrin clot formation.

BACKGROUND: Platelet derived extracellular vesicles (EVs) display a pro-coagulant phenotype and are generated throughout platelet concentrate (PC) storage. Cold storage (CS) of PCs is thought to provide a superior haemostatic advantage over room temperature (RT) storage and could prolong the storage time. However, the effect of storage conditions on EV generation and PC function is unknown. We investigated EV production under CS and RT conditions and assessed whether these EVs exhibited a more pro-coagulant phenotype in model experiments. MATERIALS AND METHODS: Buffy-coat-derived PCs in a platelet additive solution (PAS) to plasma ratio of approximately 65:35 were stored at RT (22 ± 2°C) or CS (4 ± 2°C) for a prolonged storage duration of 20 days. Impedance aggregometry assessed platelet function. EVs were isolated throughout storage and quantified using nanoparticle tracking analysis. EVs were applied to a coagulation assay to assess the impact on fibrin clot formation and lysis. RESULTS: CS produced significantly larger EVs from day 4 onwards. EV concentration was significantly increased in CS compared to RT from day 15. EVs, regardless of storage, significantly reduced time to clot formation and maximum optical density measured compared to the no EV control. Clot formation was proportionate to the number of EV applied but was not statistically different across storage conditions when corrected for EV number. CONCLUSION: EVs in CS and RT units showed similar clot formation capacity. However, the higher number of larger EVs generated in CS compared to RT suggests PC units derived from CS conditions may overall exhibit a haemostatically superior capacity compared to RT storage.