Comparison of explicit and mean-field models of cytoskeletal filaments with crosslinking motors

In cells, cytoskeletal filament networks are responsible for cell movement, growth, and division. Filaments in the cytoskeleton are driven and organized by crosslinking molecular motors. In reconstituted cytoskeletal systems, motor activity is responsible for far-from-equilibrium phenomena such as active stress, self-organized flow, and spontaneous nematic defect generation. How microscopic interactions between motors and filaments lead to larger-scale dynamics remains incompletely understood. To build from motor-filament interactions to predict bulk behavior of cytoskeletal systems, more computationally efficient techniques for modeling motor-filament interactions are needed. Here we derive a coarse-graining hierarchy of explicit and continuum models for crosslinking motors that bind to and walk on filament pairs. We compare the steady-state motor distribution and motor-induced filament motion for the different models and analyze their computational cost. All three models agree well in the limit of fast motor binding kinetics. Evolving a truncated moment expansion of motor density speeds the computation by $10^3$--$10^6$ compared to the explicit or continuous-density simulations, suggesting an approach for more efficient simulation of large networks. These tools facilitate further study of motor-filament networks on micrometer to millimeter length scales.Comment: 54 pages, 7 figures, 1 tabl

Combining Islamic Equity Portfolios and Digital Currencies: Evidence from Portfolio Diversification

Digital currencies are unregulated and potentially have a destabilizing effect coupled with increased concerns over capital gains and losses in a high volatility environment. When added to a portfolio, this currency may have certain driving factors in terms of return and risks in the case of portfolio diversification. In this study, from the Sharia angle, we follow the position of Monzer Kahf (Fatwa on Bitcoin (by Monzer Kahf). http://lightuponlight.com/blog/fatwa-on-bitcoin-by-monzer-kahf/. Accessed 03 Feb 2020, 2017) who explained that Bitcoin is considered “Like any other currency”. It should be used under the “same conditions of exchanging currencies”. Therefore, we explore the effects of adding digital currencies to an Islamic portfolio by relying on a mean-variance efficient frontier and comparing the risk-return of portfolios with and without digital currencies for different scenarios. The results show that by adding digital currencies to Shariah-compliant portfolios, its performance improves; but this depends more or less on the increase in returns than in the reduction of total risk. Specifically, digital currencies may have a big role in bringing high risks with speculative effect in portfolio diversification. Therefore, we provide some recommendations to investors and regulators to secure these currencies in Islamic capital markets

Identifying social distress: a cross-sectional survey of social outcomes 12 to 36 months after colorectal cancer diagnosis

Purpose: To establish the prevalence and determinants of poor social outcomes after a diagnosis of colorectal cancer (CRC). Patients and Methods: All 12- to 36-month survivors of CRC (International Classification of Diseases [10th revision] codes C18 to C20) diagnosed in 2010 or 2011 and treated in the English National Health Service were identified and sent a questionnaire from their treating cancer hospital. This included the Social Difficulties Inventory, a 16-item scale of social distress (SD) comprising everyday living, money matters, and self and others subscales, plus five single items. Sociodemographic and clinical data were also collected. Analyses using descriptive statistics, 2 tests, and logistic regression models were conducted. Results: Response rate was 63.3% (21,802 of 34,467). Of the 21,802 participants, 17,830 (81.8%) completed all SD items; 2,688 (15.1%) of these 17,830 respondents were classified as experiencing SD (everyday living, 19.5%; money matters, 15.6%; self and others, 18.1%). Multivariable analysis demonstrated having three long-term conditions was the strongest predictor of SD (odds ratio [OR], 6.64; 95% CI, 5.67 to 7.77 compared with no long-term conditions), followed by unemployment (OR, 5.11; 95% CI, 4.21 to 6.20 compared with being employed), having recurrent or nontreatable disease (OR, 2.75; 95% CI, 2.49 to 3.04 compared with being in remission), and having a stoma (OR, 2.10; 95% CI, 1.86 to 2.36 compared with no stoma). Additional predictors of SD were young age (< 55 years), living in a more deprived area, nonwhite ethnicity, having advanced-stage disease, having undergone radiotherapy, and being a carer. Conclusion: Although it is reassuring a majority do not experience social difficulties, a minority reported significant SD 12 to 36 months after diagnosis of CRC. The identified clinical and social risk factors are easy to establish and should be used to target support

Real-time in vivo Cherenkoscopy Imaging During External Beam Radiation Therapy

Cherenkov radiation is induced when charged particles travel through dielectric media (such as biological tissue) faster than the speed of light through that medium. Detection of this radiation or excited luminescence during megavoltage external beam radiotherapy (EBRT) can allow emergence of a new approach to superficial dose estimation, functional imaging, and quality assurance for radiation therapy dosimetry. In this letter, the first in vivo Cherenkov images of a real-time Cherenkoscopy during EBRT are presented. The imaging system consisted of a time-gated intensified charge coupled device (ICCD) coupled with a commercial lens. The ICCD was synchronized to the linear accelerator to detect Cherenkov photons only during the 3.25-μs radiation bursts. Images of a tissue phantom under irradiation show that the intensity of Cherenkov emission is directly proportional to radiation dose, and images can be acquired at 4.7  frames/s with SNR\u3c30 . Cherenkoscopy was obtained from the superficial regions of a canine oral tumor during planned, Institutional Animal Care and Use Committee approved, conventional (therapeutically appropriate) EBRT irradiation. Coregistration between photography and Cherenkoscopy validated that Cherenkov photons were detected from the planned treatment region. Real-time images correctly monitored the beam field changes corresponding to the planned dynamic wedge movement, with accurate extent of overall beam field, and expected cold and hot regions

Oxygen Tomography by Čerenkov-Excited Phosphorescence during External Beam Irradiation

The efficacy of radiation therapy depends strongly on tumor oxygenation during irradiation. However, current techniques to measure this parameter in vivo do not facilitate routine monitoring in patients. Herein, we demonstrate a noninvasive method for tomographic imaging of oxygen partial pressure (pO2 ) in deep tissue using the phosphorescence decay of an oxygen-sensitive probe excited by Čerenkov radiation induced by external beam radiotherapy. Tissue-simulating scattering phantoms (60 mm diameter with a 20 mm anomaly) containing platinum(II)-G4 (PtG4), a dendritic porphyrin-based phosphor, whose phosphorescence is quenched in the presence of oxygen, were irradiated with a clinical linear accelerator. The emitted phosphorescence was measured at various positions on the phantom boundary using a spectrograph coupled to an intensified charge-coupled device (ICCD). At each position, PtG4 phosphorescence decay curves were measured by synchronizing the ICCD to the linear accelerator pulses. Tomographic images of phosphorescence yield and lifetime were recovered for phantoms with homogenous PtG4 concentrations and heterogeneous pO2 . Since PtG4 lifetime is strongly and predictably dependent on pO 2 through the Stern-Volmer relationship, tomographic images of pO 2 were also reported, and showed excellent agreement with independent oxygenation measurements. Translating this approach to the clinic could facilitate direct sensing of pO2 during radiotherapy

Health-related quality of life after treatment for bladder cancer in England

Background Little is known about quality of life after bladder cancer treatment. This common cancer is managed using treatments that can affect urinary, sexual and bowel function. Methods To understand quality of life and inform future care, the Department of Health (England) surveyed adults surviving bladder cancer 1–5 years after diagnosis. Questions related to disease status, co-existing conditions, generic health (EQ-5D), cancer-generic (Social Difficulties Inventory) and cancer-specific outcomes (Functional Assessment of Cancer Therapy—Bladder). Results In total, 673 (54%) patients responded; including 500 (74%) men and 539 (80%) with co-existing conditions. Most respondents received endoscopic treatment (60%), while 92 (14%) and 99 (15%) received radical cystectomy or radiotherapy, respectively. Questionnaire completion rates varied (51–97%). Treatment groups reported ≥1 problem using EQ-5D generic domains (59–74%). Usual activities was the most common concern. Urinary frequency was common after endoscopy (34–37%) and radiotherapy (44–50%). Certain populations were more likely to report generic, cancer-generic and cancer-specific problems; notably those with co-existing long-term conditions and those treated with radiotherapy. Conclusion The study demonstrates the importance of assessing patient-reported outcomes in this population. There is a need for larger, more in-depth studies to fully understand the challenges patients with bladder cancer face

The Paradox of Power in CSR: A Case Study on Implementation

Purpose Although current literature assumes positive outcomes for stakeholders resulting from an increase in power associated with CSR, this research suggests that this increase can lead to conflict within organizations, resulting in almost complete inactivity on CSR. Methods A single in-depth case study, focusing on power as an embedded concept. Results Empirical evidence is used to demonstrate how some actors use CSR to improve their own positions within an organization. Resource dependence theory is used to highlight why this may be a more significant concern for CSR. Conclusions Increasing power for CSR has the potential to offer actors associated with it increased personal power, and thus can attract opportunistic actors with little interest in realizing the benefits of CSR for the company and its stakeholders. Thus power can be an impediment to furthering CSR strategy and activities at the individual and organizational level