Combining detrended cross-correlation analysis with Riemannian geometry-based classification for improved brain-computer interface performance.

Riemannian geometry-based classification (RGBC) gained popularity in the field of brain-computer interfaces (BCIs) lately, due to its ability to deal with non-stationarities arising in electroencephalography (EEG) data. Domain adaptation, however, is most often performed on sample covariance matrices (SCMs) obtained from EEG data, and thus might not fully account for components affecting covariance estimation itself, such as regional trends. Detrended cross-correlation analysis (DCCA) can be utilized to estimate the covariance structure of such signals, yet it is computationally expensive in its original form. A recently proposed online implementation of DCCA, however, allows for its fast computation and thus makes it possible to employ DCCA in real-time applications. In this study we propose to replace the SCM with the DCCA matrix as input to RGBC and assess its effect on offline and online BCI performance. First we evaluated the proposed decoding pipeline offline on previously recorded EEG data from 18 individuals performing left and right hand motor imagery (MI), and benchmarked it against vanilla RGBC and popular MI-detection approaches. Subsequently, we recruited eight participants (with previous BCI experience) who operated an MI-based BCI (MI-BCI) online using the DCCA-enhanced Riemannian decoder. Finally, we tested the proposed method on a public, multi-class MI-BCI dataset. During offline evaluations the DCCA-based decoder consistently and significantly outperformed the other approaches. Online evaluation confirmed that the DCCA matrix could be computed in real-time even for 22-channel EEG, as well as subjects could control the MI-BCI with high command delivery (normalized Cohen's κ: 0.7409 ± 0.1515) and sample-wise MI detection (normalized Cohen's κ: 0.5200 ± 0.1610). Post-hoc analysis indicated characteristic connectivity patterns under both MI conditions, with stronger connectivity in the hemisphere contralateral to the MI task. Additionally, fractal scaling exponent of neural activity was found increased in the contralateral compared to the ipsilateral motor cortices (C4 and C3 for left and right MI, respectively) in both classes. Combining DCCA with Riemannian geometry-based decoding yields a robust and effective decoder, that not only improves upon the SCM-based approach but can also provide relevant information on the neurophysiological processes behind MI.

Transfer learning promotes acquisition of individual BCI skills.

Subject training is crucial for acquiring brain-computer interface (BCI) control. Typically, this requires collecting user-specific calibration data due to high inter-subject neural variability that limits the usability of generic decoders. However, calibration is cumbersome and may produce inadequate data for building decoders, especially with naïve subjects. Here, we show that a decoder trained on the data of a single expert is readily transferrable to inexperienced users via domain adaptation techniques allowing calibration-free BCI training. We introduce two real-time frameworks, (i) Generic Recentering (GR) through unsupervised adaptation and (ii) Personally Assisted Recentering (PAR) that extends GR by employing supervised recalibration of the decoder parameters. We evaluated our frameworks on 18 healthy naïve subjects over five online sessions, who operated a customary synchronous bar task with continuous feedback and a more challenging car racing game with asynchronous control and discrete feedback. We show that along with improved task-oriented BCI performance in both tasks, our frameworks promoted subjects' ability to acquire individual BCI skills, as the initial neurophysiological control features of an expert subject evolved and became subject specific. Furthermore, those features were task-specific and were learned in parallel as participants practiced the two tasks in every session. Contrary to previous findings implying that supervised methods lead to improved online BCI control, we observed that longitudinal training coupled with unsupervised domain matching (GR) achieved similar performance to supervised recalibration (PAR). Therefore, our presented frameworks facilitate calibration-free BCIs and have immediate implications for broader populations-such as patients with neurological pathologies-who might struggle to provide suitable initial calibration data.

Interrogating a Mixed Actinide Basket Using High-Resolution γ-Ray Spectrometry: A Nuclear Forensic Perspective on Possible Smuggling Scenarios.

The total fissile content in seized nuclear materials is of immense importance and needs to be estimated with reasonable accuracy as a part of nuclear forensics for early decision-making in legal proceedings. High-resolution γ-ray spectrometry (HRGRS), because of its nondestructive nature, is a powerful tool for the assay of such samples to reach a quick "on-site" decision on the severity, intended use, and associated radiological threat. If the seized package contains fissile isotopes of more than one actinide in a multicompartmental heterogeneous mixture, analogous to the most likely scenario of a "smuggled mixed actinide basket", its "on-site" quantification can be extremely challenging. This makes up an increasing share of the absolute HRGRS in nuclear forensics and demands for fundamentally new approaches. In the present work, the challenges associated with varying attenuation experienced by γ-rays of different actinides at different subcontainments of the heterogeneous sample matrix have been addressed by an iterative efficiency transfer approach from "point" to "extended" source for individual actinides and demonstrated for the assay of four mock-up samples and a legacy packet, mimicking seized packages containing nuclear materials. An absolute isotopic inventory of the fissile and other radioisotopes has been obtained within <10% along with the assay of total U and Pu within <3% of the expected values with measurement uncertainty <10% for the majority. The present approach has a good potential for "on-site" nuclear forensics in nuclear smuggling scenarios and also can be adapted easily for a wide variety of other applications.

In View of "On-Site" Nuclear Forensics and Assay of Fissile Materials in Sealed Packages by High-Resolution γ-Ray Spectrometry.

Several incidences of nuclear smuggling during the past few decades have raised the demand for the development of a strong "on-site" nuclear forensic infrastructure. High-resolution γ-ray spectrometry (HRGRS) plays an important role in nuclear forensics. However, the existing methodologies, developed primarily for nuclear fuel cycle applications, are relative and rely on the availability of a standard, limiting their use for the absolute assay of special nuclear materials in nonstandard geometry samples with an unknown matrix, which is vital to make a quick "on-site" decision on the severity, potential radiological threat, and intended use of an interdicted package. In this work, a methodology has been developed using HRGRS for quantifying fissile (235U, 239Pu) and other radioisotopes, which is applicable to sealed packages without requiring the knowledge of the sample geometry and the matrices. By combining experiments and Monte Carlo simulations, an iterative methodology has been proposed for "point" to "extended" source absolute efficiency transformation and demonstrated further for the absolute isotopic assay of uranium and plutonium standards, mock-up nuclear forensic samples, and an unknown nuclear material mixture with a nonstandard geometry, compound matrices, and a wide variation in the elemental and isotopic compositions with a view to imitate an "on-site" experience. The present methodology requires an assay time of only a few minutes to an hour and thus promises "on-site" nuclear forensic analysis of suspected flagged packages at borders and ports using high-resolution γ-ray spectrometry. Furthermore, the present methodology is versatile and can also be adopted for wider applications, beyond nuclear forensics.

Analysis of Anxiety, Depression and Fear of Progression at 12 Months Post-Cytoreductive Surgery in the SOCQER-2 (Surgery in Ovarian Cancer-Quality of Life Evaluation Research) Prospective, International, Multicentre Study.

Patients with ovarian cancer (OC) often experience anxiety, depression and fear of progression (FOP); however, it is unclear whether surgical complexity has a role to play. We investigated the prevalence of anxiety, depression and FOP at 12 months post-cytoreductive surgery and investigated associations with surgical complexity, patient (age, ethnicity, performance status, BMI) and tumour (stage, disease load) factors. One hundred and forty-one patients with FIGO Stage III-IV OC, who did not have disease progression at 12 months post-surgery, completed the Hospital Anxiety and Depression Scale and FOP short-form questionnaire. Patients underwent surgery with low (40.4%), intermediate (31.2%) and high (28.4%) surgical complexity scores. At 12 months post-surgery, 99 of 141 (70%) patients with advanced OC undergoing surgery experienced clinically significant anxiety, 21 of 141 (14.9%) patients experienced moderate to severe depression and 37 of 140 (26.4%) experienced dysfunctional FOP. No associations were identified between the three different surgical complexity groups with regards to anxiety, depression or FOP scores. Unsurprisingly, given the natural history of the disease, most patients with OC suffer from anxiety, depression and fear of progression after completion of first-line cancer treatment. Surgical complexity at the time of surgery is not associated with a deleterious impact on anxiety, depression or FOP for patients with OC. Patients with OC experience a profound mental health impact and should be offered mental health support throughout their cancer journey.

Investigating the Impact of Ultra-Radical Surgery on Survival in Advanced Ovarian Cancer Using Population-Based Data in a Multicentre UK Study.

We investigated URS and impact on survival in whole patient cohorts with AOC treated within gynaecological cancer centres that participated in the previously presented SOCQER 2 study. National cancer registry datasets were used to identify FIGO Stage 3,4 and unknown stage patients from 11 cancer centres that had previously participated in the SOCQER2 study. Patient outcomes' association with surgical ethos were evaluated using logistic regression and Cox proportional hazards. Centres were classified into three groups based on their surgical complexity scores (SCS); those practicing mainly low complexity, (5/11 centres with >70% low SCS procedures, 759 patients), mainly intermediate (3/11, 35−50% low SCS, 356 patients), or mainly high complexity surgery (3/11, >35% high SCS, 356 patients). Surgery rates were 43.2% vs. 58.4% vs. 60.9%. across mainly low, intermediate and high SCS centres, respectively, p < 0.001. Combined surgery and chemotherapy rates were 39.2% vs. 51.8% vs. 38.3% p < 0.000 across mainly low, intermediate and high complexity groups, respectively. Median survival was 23.1 (95% CI 19.0 to 27.2) vs. 22.0 (95% CI 17.6 to 26.3) vs. 17.9 months (95% CI 15.7 to 20.1), p = 0.043 in mainly high SCS, intermediate, and low SCS centres, respectively. In an age and deprivation adjusted model, compared to patients in the high SCS centres, patients in the low SCS group had an HR of 1.21 (95% CI 1.03 to 1.40) for death. Mainly high/intermediate SCS centres have significantly higher surgery rates and better survival at a population level. Centres that practice mainly low complexity surgery should change practice. This study provides support for the utilization of URS for patients with advanced OC.

Quality of life from cytoreductive surgery in advanced ovarian cancer: Investigating the association between disease burden and surgical complexity in the international, prospective, SOCQER-2 cohort study.

OBJECTIVE: To investigate quality of life (QoL) and association with surgical complexity and disease burden after surgical resection for advanced ovarian cancer in centres with variation in surgical approach. DESIGN: Prospective multicentre observational study. SETTING: Gynaecological cancer surgery centres in the UK, Kolkata, India, and Melbourne, Australia. SAMPLE: Patients undergoing surgical resection (with low, intermediate or high surgical complexity score, SCS) for late-stage ovarian cancer. MAIN OUTCOME MEASURES: Primary: change in global score on the European Organisation for Research and Treatment of Cancer (EORTC) core quality-of-life questionnaire (QLQ-C30). Secondary: EORTC ovarian cancer module (OV28), progression-free survival. RESULTS: Patients' preoperative disease burden and SCS varied between centres, confirming differences in surgical ethos. QoL response rates were 90% up to 18 months. Mean change from the pre-surgical baseline in the EORTC QLQ-C30 was 3.4 (SD 1.8, n = 88) in the low, 4.0 (SD 2.1, n = 55) in the intermediate and 4.3 (SD 2.1, n = 52) in the high-SCS group after 6 weeks (p = 0.048), and 4.3 (SD 2.1, n = 51), 5.1 (SD 2.2, n = 41) and 5.1 (SD 2.2, n = 35), respectively, after 12 months (p = 0.133). In a repeated-measures model, there were no clinically or statistically meaningful differences in EORTC QLQ-C30 global scores between the three SCS groups (p = 0.840), but there was a small statistically significant improvement in all groups over time (p < 0.001). The high-SCS group experienced small to moderate decreases in physical (p = 0.004), role (p = 0.016) and emotional (p = 0.001) function at 6 weeks post-surgery, which resolved by 6-12 months. CONCLUSIONS: The global QoL of patients undergoing low-, intermediate- and high-SCS surgery improved at 12 months after surgery and was no worse in patients undergoing extensive surgery. TWEETABLE ABSTRACT: Compared with surgery of lower complexity, extensive surgery does not result in poorer quality of life in patients with advanced ovarian cancer.

Does sites of recurrence impact survival in secondary cytoreduction surgery for recurrent epithelial ovarian cancer?

Outcomes of secondary cytoreduction surgery (SCS) were evaluated for morbidity, progression free survival (PFS) and overall survival (OS) and factors influencing results were explored. Retrospective analysis of all cases of SCS for epithelial ovarian cancer (EOC) was performed from October 2010 to December 2017. 62 patients were prospectively identified as candidates for SCS and 57 underwent SCS. 20(35%) patients required bowel resection/s, 24(42%) had nodal resections and 11(19%) had extensive upper abdominal surgery. 51(89%) achieved complete cytoreduction. After a median follow-up of 30 months (range 9-95 months), median PFS was 32 months (CI 17-76 months) and median OS has not reached. Seventeen patients have died and 32 have progressed. Three patients had Clavien-Dindo grade-3 and two had grade-4 morbidity. Patients who had multi-site recurrence had shorter median PFS (p = 0.04) and patients who required bowel resections had lower median OS (p = 0.009) compared to rest of the cohort.IMPACT STATEMENTWhat is already known on this subject? Retrospective studies have confirmed survival advantage for recurrence in epithelial ovarian cancer and recommend SCS for carefully selected patients. This finding is being evaluated in randomised control trials currently.What do the results of this study add? This study presents excellent results for survival outcomes after SCS and highlights importance of careful selection of patients with a goal to achieve complete cytoreduction. In addition, for the first time in literature, this study also explores various factors that may influence results and finds that there are no differences in survival outcomes whether these patients had early stage or advanced stage disease earlier. Patients who have multisite recurrence tend to have shorter PFS but no difference were noted for overall survival. Patients who have recurrence in bowels necessitating resection/s have a shorter median OS compared to rest of cohorts, however, still achieving a good survival time.What are the implications of these findings for clinical practice and/or further research? These findings will raise awareness for the clinicians and patients while discussing surgical outcomes and would set an achievable standard to improve cancer services. The pattern of recurrence and associated outcomes also point towards difference in biological nature of recurrent disease and could provide an opportunity for scientists to study the biological makeup of these recurrent tumours.

Quality of life outcomes following surgery for advanced ovarian cancer: a systematic review and meta-analysis.

BACKGROUND: Quality of life after ovarian cancer treatment is an important goal for patients. Complex debulking surgeries and platinum based chemotherapy are often required but quality of life after surgery is rarely reported. OBJECTIVES: To describe quality of life outcomes after surgery for advanced ovarian cancer in a systematic review and meta-analysis. SEARCH STRATEGY: MEDLINE, EMBASE, and CENTRAL through March 2019 with no language restrictions. SELECTION CRITERIA: Included studies reported quality of life in women diagnosed with primary advanced ovarian cancer, fallopian tube carcinoma or primary peritoneal cancer undergoing cytoreduction surgery. DATA COLLECTION AND ANALYSIS: Data on extent and timing of surgery, quality of life outcomes, and surgical complications were extracted and study quality assessed. RESULTS: Three randomized controlled trials comparing primary surgery to neoadjuvant chemotherapy had heterogeneous quality of life outcomes with no difference between arms, although there was a clinical improvement in global quality of life scores in both arms at 6 months compared with baseline. Data from two observational studies showed no meaningful difference in quality of life scores between patients undergoing standard or extensive surgery at 6 months. CONCLUSIONS: There was no clinically important difference in the quality of life of patients undergoing either primary debulking surgery or neoadjuvant chemotherapy. There is insufficient evidence on quality of life outcomes of patients undergoing extensive or ultra-radical surgery compared with those undergoing less extensive surgery. Quality of life outcomes matter to patients, but there is little evidence to inform patient choice regarding the extent of surgery.

Structural, transport and optical properties of (La0.6Pr0.4)0.65Ca0.35MnO3 nanocrystals: a wide band-gap magnetic semiconductor.

(La0.6Pr0.4)0.65Ca0.35MnO3 system has been synthesized via a sol-gel route at different sintering temperatures. Structural, transport and optical measurements have been carried out to investigate (La0.6Pr0.4)0.65Ca0.35MnO3 nanoparticles. Raman spectra show that Jahn-Teller distortion has been decreased due to the presence of Ca and Pr in A-site. Magnetic measurements provide a Curie temperature around 200 K and saturation magnetization (MS) of about 3.43µB/Mn at 5 K. X-ray photoemission spectroscopy study suggests that Mn exists in a dual oxidation state (Mn(3+) and Mn(4+)). Resistivity measurements suggest that charge-ordered states of Mn(3+) and Mn(4+), which might be influenced by the presence of Pr, have enhanced insulating behavior in (La0.6Pr0.4)0.65Ca0.35MnO3. Band gap estimated from UV-Vis spectroscopy measurements comes in the range of wide band gap semiconductors (∼3.5 eV); this makes (La0.6Pr0.4)0.65Ca0.35MnO3 a potential candidate for device application.