LS Criterion Research Articles

Using leaf regrowth stage to define defoliation interval for diverse pastures of complementary species (Lolium perenne L., Bromus valdivianus Phil., Dactylis glomerata L. and Trifolium repens L.)

Diverse pastures of complementary species (DPCS) comprise species that fulfil different agroecological niches, resulting in growth asynchrony and complementarity of functional roles. It is expected that DPCS have a greater capability to tolerate and performunder increasingly extreme climate events, providing a potential alternative for New Zealand pastoral systems. In the present study, DPCS comprised Lolium perenne L., Bromus valdivianus Phil., Dactylis glomerata L., and Trifolium repens L. The leaf regrowth stage [LS; L. perenne (2.5-3.0LS), B. valdivianus (3.5-4.0LS) and D. glomerata (3.5-4.0LS)] is proposed to be an applicable method of defoliation management for DPCS due to a potential overlapping of the defoliation interval. The seasonal and annual herbage mass accumulation and botanical composition of DPCS and their respective single-grass and T. repens pastures under the LS criterion were assessed. The annual yield did not differ among pastures (average 20.26 t dry matter (DM) ha- 1). However, significant differences were found within seasons, with DPCS exhibiting asynchronous growth among species that reduced the seasonality of herbageaccumulation and invasion by volunteer species. Lolium perenne, B. valdivianus and D. glomerata were shown to be complementary grass species, presenting growth asynchrony and an overlapping defoliation interval that optimised production, indicating that defoliation based on LS criterion is a suitable management for DPCS.

Prevalence of pathogenic mutations and variants of uncertain significance in patients undergoing hereditary cancer genetic testing in Cambridge, MA.

e22506 Background: Genetic testing allows for enhanced prognostication and early intervention in patients with high risk of developing cancer. Genetic testing often reveals variants of uncertain significance (VUS), for which association with disease risk is unclear. The ambiguity of this finding creates a dilemma for patients and providers and has been associated with significant communication error and distress. In this retrospective observational study, we seek to characterize the indications, outcomes, and trends in patients undergoing genetic testing in a community hospital in Cambridge, MA. As our study spanned the beginning of the COVID-19 pandemic, we also assessed its impact on care accessibility. Methods: We included patients undergoing genetic testing at our hospital between December 2019 and October 2020 (n=371). Medical charts were abstracted to identify patient characteristics, family history, indication for genetic testing, genetic findings, and subsequent management. Results: Our population had a mean age of 48 years (SD=15), was predominantly female (88.1%), and had a high proportion of Ashkenazi Jewish descent (15.3%). The vast majority (351, 94.6%) had a family history of cancer, while 123 (33.2%) had a personal history of cancer, most commonly breast (n=89). The most common indications for genetic testing were Hereditary Breast and Ovarian Cancer (HBOC in 280, 75%), Lynch Syndrome (LS in 22, 5.9%), and Familial Adenomatous Polyposis (FAP in 7, 2%). Of patients who met HBOC, LS, or FAP criteria for genetic testing, pathogenic mutations were identified in 9.5% and VUS in 28.6%. Out of total 35 (9.4%) pathogenic mutations found in our entire study population, the most common were in BRCA (9, 25.7%), MUTYH (5, 14.2%), and Lynch genes (3, 8.6%). Out of 103 patients with VUS (27.8%), the most common sites were APC (14) and MSH3 (9). We found no significant trend in genetic counseling consultations over our 11 months study period despite the COVID-19 pandemic (R2 = 0.006). Conclusions: Among patients who met criteria for genetic cancer screening at a community hospital, 9.5% were found to have a pathogenic mutation while 28.6% were found to have VUS. These numbers are comparable to previously published estimates. Despite advances in our understanding of genetic colon and gynecological cancers, the majority of patients presenting for genetic cancer counseling continue to do so due to breast cancer concerns. Lastly, we noted high efficacy in our conversion of in-person genetics consultations to telemedicine during the COVID-19 pandemic, suggesting telemedicine is a robust format for genetic counselling. Mutations (N): BRCA1 (3), BRCA2 (6); MUTHY (5); MSH2 (2), MSH6 (1); ATM (2), and one each in PALB2, RAD50, RAD51C, RAD51D, Tp53, CDKN2A, APC, F2, SDHA, SDHB, VHL. FANCL, NTHL1.

GENERALIZED LAPLACE INFERENCE IN MULTIPLE CHANGE-POINTS MODELS

Under the classical long-span asymptotic framework, we develop a class of generalized laplace (GL) inference methods for the change-point dates in a linear time series regression model with multiple structural changes analyzed in, e.g., Bai and Perron (1998,Econometrica66, 47–78). The GL estimator is defined by an integration rather than optimization-based method and relies on the LS criterion function. It is interpreted as a classical (non-Bayesian) estimator, and the inference methods proposed retain a frequentist interpretation. This approach provides a better approximation about the uncertainty in the data of the change-points relative to existing methods. On the theoretical side, depending on some input (smoothing) parameter, the class of GL estimators exhibits a dual limiting distribution, namely the classical shrinkage asymptotic distribution or a Bayes-type asymptotic distribution. We propose an inference method based on highest density regions using the latter distribution. We show that it has attractive theoretical properties not shared by the other popular alternatives, i.e., it is bet-proof. Simulations confirm that these theoretical properties translate to good finite-sample performance.

Prediction error identification of linear dynamic networks with rank-reduced noise

Dynamic networks are interconnected dynamic systems with measured node signals and dynamic modules reflecting the links between the nodes. We address the problem of identifying a dynamic network with known topology, on the basis of measured signals, for the situation of additive process noise on the node signals that is spatially correlated and that is allowed to have a spectral density that is singular. A prediction error approach is followed in which all node signals in the network are jointly predicted. The resulting joint-direct identification method, generalizes the classical direct method for closed-loop identification to handle situations of mutually correlated noise on inputs and outputs. When applied to general dynamic networks with rank-reduced noise, it appears that the natural identification criterion becomes a weighted LS criterion that is subject to a constraint. This constrained criterion is shown to lead to maximum likelihood estimates of the dynamic network and therefore to minimum variance properties, reaching the Cramér–Rao lower bound in the case of Gaussian noise. In order to reduce technical complexity, the analysis is restricted to dynamic networks with strictly proper modules.

Digital Self-Interference Cancellation With Variable Fractional Delay FIR Filter for Full-Duplex Radios

In full-duplex radios, delay alignment errors result in random mismatch between the self-interference (SI) signal and the reconstructed cancellation signal, leading to the performance degradation of the SI cancellation. In this letter, a variable fractional delay (VFD) FIR filter with more precise delay alignment is exploited to suppress the SI in digital domain. The closed-form expressions of the VFD FIR filter coefficients are reformulated by minimizing the residual SI power. Based on the obtained SI cancellation capability, the influence of the filter order on the SI cancellation is then characterized. Simulations show that the deployment of the VFD FIR filter significantly enhances the SI cancellation performance. Specifically, when the SI signal bandwidths are 0.5 and 10 MHz, the cancellation capability of employing the VFD FIR filter based on the proposed coefficients outperforms the VFD FIR filter under the LS criterion by 6.5 and 3.7 dB, respectively, which presents a potential contribution to enhance the SI cancellation performance.

Employing Volterra filters in the ADPCM technique for speech coding: a comprehensive investigation

AbstractAlthough linear filters are useful in a various applications in the context of speech processing, there are several evidences for existence of nonlinearity in speech signals. Our main aim is to launch a comprehensive investigation into the exploitation of nonlinear Volterra filters in the context of the ADPCM‐based speech coding technique, using two methods of forward prediction, based on the LS criterion, and backward prediction, based on both LMS and RLS adaptation algorithms. In any case, after solving some innate problems, for example, ill‐conditioning and instability, schemes for optimum exploitation of nonlinear prediction are developed and simulation results are provided, tested with several performance criteria. With forward prediction a scheme is developed to detect and flag those frames for which, after stabilizing, including the quadratic predictor is beneficial. Scalar and vector quantisation methods are used for quantising the residual signal and the filter parameters, respectively. The results show that using this scheme a negligible improvement (up to 0.62 dB in the SNR) can be achieved, in spite of the increase in bit rate and complexity. With backward prediction two frame‐based schemes are developed in which for each frame, after examining a set of quadratic filters, the best filter in the sense of the best quality of the reconstructed speech is selected. The ultimate schemes result in an improvement of up to 1.5 dB in the overall SNR of the reconstructed speech at the cost of a slight increase in the bit‐rate, a short delay and a demanding increase in the complexity. Copyright © 2010 John Wiley & Sons, Ltd.

Rayleigh time‐varying channel complex gains estimation and ICI cancellation in OFDM systems

AbstractIn this paper, we consider an orthogonal frequency division multiplexing (OFDM) mobile communication system operating in downlink mode in a time‐varying multipath Rayleigh channel scenario. We present a mean square error (MSE) theoretical analysis for a multipath channel complex gains estimation algorithm with inter‐sub‐carrier interference (ICI) reduction using a comb‐type pilot. Assuming the presence of delay‐related information, the time average of the multipath complex gains, over the effective duration of each OFDM symbol, are estimated using LS criterion. After that, the time‐variation of the multipath complex gains within one OFDM symbol are obtained by interpolating the time‐averaged symbol values using low‐pass interpolation. Hence, the channel matrix, which contains the channel frequency response and the coefficients of ICI, can be computed and the ICI can be reduced by using successive interference suppression (SIS) in data symbol detection. The algorithm's performance is further enhanced by an iterative procedure, performing channel estimation and ICI suppression at each iteration. Theoretical analysis and simulation results show a significant performance improvement for high normalised Doppler spread (especially after the first iteration) in comparison to conventional methods. Copyright © 2009 John Wiley & Sons, Ltd.

8 Assessing cancer treatment morbidity using the LENT SOMA scales in cervical carcinoma

Methods: 145 patients, who had received radiotherapy for cervical carcinoma more than three years ago, were invited for an assessment to answer questionnaires with a research nurse and offered a medical consultation. The questionnaires were devised from the published scores for LENT SOMA to obtain subjective scores of late effects at each organ site affected by the pelvic radiotherapy fields. This work was the result of collaboration with the departments of clinical oncology, psychological medicine and medical statistics. The questionnaires evolved over a period of 18 months with the fourth draft deemed satisfactory. Questions were used to obtain the objective evidence of treatment effect along with clinical examination and review of the medical notes to assess and record management and analytic evidence based on imaging results. Quality of life was assessed using the EORTC Core30 questionnaire (with permission) and scored according to the algorithm provided by the EORTC QOL study group (Aarondsen et a1,1993). The Hospital Anxiety and Depression Scale questionnaire was also used. Results: 100 patients attended for interview and assessment. Scores for each organ site - 6 sites uterus/cervix, ovary/reproductive, rectum/bowel, bladder/urethra, ureter/kidney and vagina were obtained. Total scores were calculated for subjective and objective criteria using an average score as recommended by the working groups that devised the LS scales. In addition, the maximum scores for each organ site were obtained. The objective LS scores for rectum/bowel correlated significantly with the FI scores, rho =0.79,p<0.0005 but there was less correlation with subjective scores, rho=0.32, p=<0.001. The objective LS score for bladder/urethra was significantly correlated with the FI score, rho =0.71 ,p<0.0005 but the subjective score was weakly correlated, rho=0.43,p<0.0005 (see figure). The total LS objective score was correlated with the total FI score, rho=0.62, p<0.0005. The total LS objective score and maximum FI score was correlated, rho=0.57, p<0.0005. The maximum scores and mean scores for each of the subsites was compared with the FI scores. Using the mean scores gave a slightly greater range and may allow greater discrimination than when using the maximum LENT SOMA score for a subsite. The total EORTC score was not well correlated with the LS objective criteria rho = -0.32, p=0.001, though there was better correlation with the subjective LS scores rho= -0.55, p<0.0005. Similarly, there was better correlation with the HAD anxiety score with the LS subjective criteria rho=0.52,p<0.0005 and HAD depression rho=0.48,p<0.0005, but the objective LS criteria were less well correlated for the HAD anxiety score, rho=0.33,p=0.001 and HAD depression, rho=0.27, p=0.007. Conclusions: The objective LENT SOMA scores were well correlated with the maximum FI score for organ sites, but less so with a total LS score. The data suggest that it may be better to look at the scores for each subsite rather than a total LS score. The subjective LS scores were less well correlated with the FI scores and this Js not surprising as the FI scoring is based on objective scoring and not taking the patients' views into account. The subjective LS scores were correlated with the EORTC and HADS scores but the objective LENT SOMA score was poorly correlated with the quality of life measurements.

Channel estimation for OFDM systems based on comb-type pilot arrangement in frequency selective fading channels

The channel estimation methods for OFDM systems based on a comb-type pilot sub-carrier arrangement are investigated. The channel estimation algorithm based on comb-type pilots is divided into pilot signal estimation and channel interpolation. The pilot signal estimation based on LS or MMSE criteria, together with channel interpolation based on piecewise-linear interpolation or piecewise second-order polynomial interpolation is studied. Owing to the MMSE estimate of the pilot signals, the inter-carrier interference and additive white Gaussian noise are reduced considerably. The computational complexity of pilot signal estimation based on MMSE criterion can be reduced by using a simplified LMMSE estimator with low-rank approximation using singular value decomposition. Phase compensators before and after interpolation are also presented to combat the phase changes of subchannel symbols arising from the frame synchronization errors. Compared to the transform-domain processing based channel estimation algorithm the MMSE estimate of pilot signals together with phase compensated linear interpolation algorithm provides a better performance and requires less computations.