5,888 research outputs found

    Cortical idiosyncrasies predict the perception of object size

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    Perception is subjective. Even basic judgments, like those of visual object size, vary substantially between observers and also across the visual field within the same observer. The way in which the visual system determines the size of objects remains unclear, however. We hypothesize that object size is inferred from neuronal population activity in V1 and predict that idiosyncrasies in cortical functional architecture should therefore explain individual differences in size judgments. Here we show results from novel behavioural methods and functional magnetic resonance imaging (fMRI) demonstrating that biases in size perception are correlated with the spatial tuning of neuronal populations in healthy volunteers. To explain this relationship, we formulate a population read-out model that directly links the spatial distribution of V1 representations to our perceptual experience of visual size. Taken together, our results suggest that the individual perception of simple stimuli is warped by idiosyncrasies in visual cortical organization

    The impact of organisational external peer review on colorectal cancer treatment and survival in the Netherlands

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    Background: Organisational external peer review was introduced in 1994 in the Netherlands to improve multidisciplinary cancer care. We examined the clinical impact of this programme on colorectal cancer care. Methods: Patients with primary colorectal cancer were included from 23 participating hospitals and 7 controls. Hospitals from the intervention group were dichotomised by their implementation proportion (IP) of the recommendations from each peer review (high IP vs low IP). Outcome measures were the introduction of new multidisciplinary therapies and survival. Results: In total, 45 705 patients were included (1990-2010). Patients from intervention hospitals more frequently received adjuvant chemotherapy for stage III colon cancer. T2-3/M0 rectal cancer patients from hospitals with a high IP had a higher chance of receiving preoperative radiotherapy (OR 1.31, 95% CI 1.11-1.55) compared with the controls and low IP group (OR 0.75, 95% CI 0.63-0.88). There were no differences in the use of preoperative chemoradiation for T4/M0 rectal cancer. Survival was slightly higher in colon cancer patients from intervention hospitals but unrelated to the phase of the programme in which the hospital was at the time of diagnosis. Conclusions: Some positive effects of external peer review on cancer care were found, but the results need to be interpreted cautiously due to the ambiguity of the outcomes and possible confounding factors

    Incidental findings during the diagnostic work-up in the head and neck cancer pathway:Effects on treatment delay and survival

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    Objectives: As a result of the increasing number of diagnostic scans, incidental findings (IFs) are more frequently encountered during oncological work-up in patients with head and neck squamous cell carcinomas (HNSCC). IFs are unintentional discoveries found on diagnostic imaging. Relevant IFs implicate clinical consequences, resulting in delay in oncologic treatment initiation, which is associated with unfavorable outcomes. This study is the first to investigate the incidence and nature of IFs over the years and establish the effect of relevant IFs on delay. Material and methods: This retrospective study compared two time periods (2010 & ndash;2011 and 2016 & ndash;2017), described associations between relevant IFs and delay in carepathway interval (days between first visit and treatment initiation) and assessed the effect of relevant IFs on overall two-year survival. Results: In total, 592 patients were included. At least one IF was found in 61.5% of the patients, most frequently on chest-CT. In 128 patients (21.6%) a relevant IF was identified, resulting for the majority in radiologist recommendations (e.g. additional scanning). Presence of a relevant IF was an independent significant factor associated with delay in treatment initiation. The risk of dying was higher for patients with a relevant IF, although not significant in the multivariable model (HR: 1.46, p = 0.079). Conclusion: In diagnostic work-up for HNSCC patients, relevant IFs are frequently encountered. As the frequency of additional imaging rises over the years, the number of IFs increased simultaneously. These relevant IFs yield clinical implications and this study described that relevant IFs result in significant delay in treatment initiation

    Impact of Delay on Hospitalization in Older Patients With Head and Neck Cancer:A Multicenter Study

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    OBJECTIVE: To assess the impact of delay in treatment initiation on hospitalization, overall survival, and recurrence in older patients with head and neck cancer (HNC). STUDY DESIGN: Retrospective multicenter study. SETTING: Two tertiary referral centers. METHODS: All patients with newly diagnosed HNC (≥60 years) treated between 2015 and 2017 were retrospectively included. Time-to-treatment intervals were assessed (ie, calendar days between first visit and start of treatment). Multiple multivariable models were performed with hospital admission days (>14 days), survival, and recurrence as dependent outcome variables. RESULTS: In total, 525 patients were enrolled. The mean age was 70.7 years and 70.7% were male. Median time to treatment was 34.0 days, and 36.3% started treatment within 30 days (P = .576 between centers). Patients with radiotherapy had longer time to treatment than surgical patients (39.0 vs 29.0 days, P 14 days) in the first year after treatment in an adjusted model (odds ratio, 4.66 [95% CI, 2.59-8.37]; P < .001). Delay in treatment initiation was not associated with overall survival or tumor recurrence. CONCLUSION: This study highlights the importance and challenges of ensuring timely treatment initiation in older patients with HNC, as treatment delay was an independent predictor of hospitalization. During oncologic workup, taking time to consider patient-centered outcomes (including minimizing time spent in hospital) while ensuring timely start of treatment requires well-structured, fast-track care pathways

    To what extent has the last two decades seen significant progress in the management of older patients with head and neck cancer?

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    Introduction: Life expectancy is rising and consequently also the number of older patients with head and neck cancer. Different treatment regimens are often applied for older patients. The aim of this study is to investigate how treatment patterns and survival rates have changed over the past 20 years in older patients with head and neck squamous cell carcinoma (HNSCC). Materials: Patient and tumour characteristics, treatment and 5-year survival data from the Netherlands Cancer Registry of patients aged >60 years diagnosed with HNSCC in 1990-1995 and 2010-2015 were compared using chi-square test and relative survival analysis. Results: Data of 14,114 patients were analyzed. Oral cavity cancer treatment did not change over time, while survival improved from 54% to 58% (p 1/4 0.03). Oropharyngeal and hypopharyngeal cancer treatment shifted towards non-surgical, with survival improving from 31% to 51% (p < 0.01) and 26% to 34% (p < 0.01), respectively. Laryngeal cancer treatment changed towards surgery in stage I and non-surgical treatment in stage III and IV disease. Survival in laryngeal cancer stage I remained stable and favorable at a relative survival rate of around 90%. Survival non-significantly changed from 54% to 49% for stage III disease and from 37% to 33% for disease. Conclusion: Relative survival increased for all head and neck cancer sites in older patients, except for laryngeal cancer. For oropharyngeal, hypopharyngeal and advanced laryngeal cancer, a shift towards non-surgical treatment modalities was observed. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY licens

    The effect of delayed primary treatment initiation on adverse events and recurrence in older head and neck cancer patients

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    Background and purpose: As a result of rapid tumor growth in head and neck squamous cell carcinoma (HNSCC), delay in treatment initiation can result in tumor progression and inferior outcome. Especially older and frail patients are prone to develop adverse events. The aim of this study was to assess the effect of delay on development of adverse events and recurrence in older HNSCC patients. Materials and methods: This cohort study with prospectively collected data included all newly diagnosed, curatively treated HNSCC patients (>60 years) between 2015 and 2017. Time-to-treatment interval and geriatric domains were assessed. Adverse events were defined as postoperative complications (ClavienDindo classification) and acute radiation-induced toxicity (Common Terminology Criteria of Adverse Events). Multivariable regression models were performed, using adverse events and recurrence as outcome variables. Results: A total of 245 patients were included. Median time-to-treatment was 26 days for surgery patients and 40 days for radiotherapy patients (p < 0.001). Delayed treatment initiation was not associated with postoperative complications or acute radiation-induced toxicity. Delay was significantly associated with recurrence risk within two years after treatment initiation in a model adjusted for stage and tumor location in patients treated with initial surgery (HR:4.1, 95%CI:1.2- 14.0, p = 0.024). For patients treated with radiotherapy, delay was not significantly associated with recurrence risk. Conclusion: Delayed treatment initiation was independently associated with increased recurrence risk in patients treated with initial surgery. Delay was not associated with short-term adverse events. These findings highlight the importance of establishing fast-track care pathways to minimize delays and improve especially long-term outcome. (c) 2022 The Authors. Published by Elsevier B.V. Radiotherapy and Oncology 173 (2022) 154-162 This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

    Determinants of delay in the head and neck oncology care pathway:The next step in value-based health care

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    Objective Head and neck squamous cell carcinomas (HNSCC) are relatively fast-growing tumours, and delay of treatment is associated with tumour progression and adverse outcomes. The aim of this study is to identify determinants of delay in a head and neck oncology centre. Methods This cohort study with prospectively collected data investigated associations between patient (including geriatric assessment at first consultation), tumour and treatment characteristics and treatment delay. Two quality indicator intervals assessing value-based healthcare were studied: care pathway interval (CPI, interval between first visit in an HNOC and treatment initiation) and time-to-treatment initiation (TTI, interval between histopathological confirmation of HNSCC and treatment initiation), using regression analyses. Results Stage-IV tumours and initial radiotherapy were independent predictors of delay in CPI. Initial radiotherapy was associated with delay in TTI. Overall, 37% of the patients started treatment within 30 days after first consultation (67% in case of initial surgical treatment and 11.5% if treated with (chemo)radiation, p <0.001). Geriatric assessment outcomes were not associated with delay. Indicators for delay in initial surgery patients were stage-IV tumours (CPI). Conclusion The majority of HNSCC patients encounter delay in treatment initiation, specifically in patients with advanced-stage tumours or when radiotherapy is indicated

    Anisotropic and strong negative magneto-resistance in the three-dimensional topological insulator Bi2Se3

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    We report on high-field angle-dependent magneto-transport measurements on epitaxial thin films of Bi2Se3, a three-dimensional topological insulator. At low temperature, we observe quantum oscillations that demonstrate the simultaneous presence of bulk and surface carriers. The magneto- resistance of Bi2Se3 is found to be highly anisotropic. In the presence of a parallel electric and magnetic field, we observe a strong negative longitudinal magneto-resistance that has been consid- ered as a smoking-gun for the presence of chiral fermions in a certain class of semi-metals due to the so-called axial anomaly. Its observation in a three-dimensional topological insulator implies that the axial anomaly may be in fact a far more generic phenomenon than originally thought.Comment: 6 pages, 4 figure

    Semiclassical corrections to the interaction energy of a hard-sphere Boltzmann gas

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    Quantum effects in statistical mechanics are important when the thermal wavelength is of the order of, or greater than, the mean interatomic spacing. This is examined at depth taking the example of a hard-sphere Boltzmann gas. Using the virial expansion for the equation of state, it is shown that the interaction energy of a classical hard-sphere gas is exactly zero. When the (second) virial coefficient of such a gas is obtained quantum mechanically, however, the quantum contribution to the interaction energy is shown to be substantial. The importance of the semiclassical corrections to the interaction energy shows up dramatically in such a system.Comment: 9 pages, 3 figures, submitted to Eur. J. Phy
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