We present an approach for approximately solving discrete-time stochastic optimal-control problems by combining direct trajectory optimization, deterministic sampling, and policy optimization. Our ...feedback motion-planning algorithm uses a quasi-Newton method to simultaneously optimize a reference trajectory, a set of deterministically chosen sample trajectories, and a parameterized policy. We demonstrate that this approach exactly recovers LQR policies in the case of linear dynamics, quadratic objective, and Gaussian disturbances. We also demonstrate the algorithm on several nonlinear, underactuated robotic systems to highlight its performance and ability to handle control limits, safely avoid obstacles, and generate robust plans in the presence of unmodeled dynamics.
Background:Increasingly women at high risk of breast cancer are opting for risk reducing surgery. The aim of this study was to assess the effectiveness of this approach in women at high risk in both ...carriers and non-carriers of BRCA1/2.Methods:Data from 10 European centres that offer a genetic counselling and screening service to women at risk were obtained prospectively from 1995. Breast cancer risks were estimated from life tables and a control group of women at risk who did not undergo surgery.Results:The combined centres have data on 550 women who have undergone risk reducing mastectomy with greater than 3334 women years of follow-up. Operations were carried out on women with lifetime risks of 25–80%, with an average expected incidence rate of 1% per year. No breast cancers have occurred in this cohort in the “at risk” unaffected breast, whereas >34 would have been expected. A high rate (2–3.6%) of occult disease was identified in the at risk breast at the time of surgery.Interpretation:We conclude that risk reducing surgery is highly effective.
Abstract
We investigated the prevalence and spatial distribution of methamphetamine clandestine laboratories in New Zealand (NZ), between 2004 and 2009 using data obtained from the NZ Police. During ...this time, there were 1,056 clandestine laboratories seized, of which, 808 (77%) were located at residential settings. SaTScan software was used to identify spatial clusters of clandestine laboratory seizures, controlling for median income, age, area deprivation level, and land-use type in an attempt to identify social factors potentially associated with the occurrence of clandestine laboratory clusters. Unadjusted analyses identified five clusters of methamphetamine laboratory seizures in the Far North (Relative Risk (RR) = 4.09, P = 0.000), West Auckland (RR= 2.0, P = 0.002), Central Auckland (RR = 7.69, P = 0.018), and Hamilton City (RR = 6.00, P < 0.001) territorial authorities. The fully adjusted model, controlling for all socio-economic variables, only accounted for three of the five spatial clusters. The persistence of the remaining clusters indicates that other unknown factors influence the distribution of clandestine laboratories in the North Island of NZ. Identifying territorial authorities with more clandestine laboratories than expected may facilitate community policing and public health interventions.
► We used a plant feedback method and remote sensing to successfully schedule irrigations. ► A CWSI calculated over daylight hours in a 24h period is useful in timing irrigations for sorghum. ► Crop ...WUE was optimal at the level of 55% replacement of soil water depletion to field capacity.
Variations of the crop water stress index (CWSI) have been used to characterize plant water stress and schedule irrigations. Usually, this thermal-based stress index has been calculated from measurements taken once daily or over a short period of time, near solar noon or after and in cloud free conditions. A method of integrating the CWSI over a day was developed to avoid the noise that may occur if weather prevents a clear CWSI signal near solar noon. This CWSI and time threshold (CWSI-TT) was the accumulated time that the CWSI was greater than a threshold value (0.45); and it was compared with a time threshold (CWSI-TT) based on a well-watered crop. We investigated the effectiveness of the CWSI-TT to automatically control irrigation of short and long season grain sorghum hybrids (Sorghum bicolor (L.) Moench, NC+ 5C35 and Pioneer 84G62); and to examine crop response to deficit irrigation treatments (i.e. 80%, 55%, 30% and 0% of full replenishment of soil water depletion to 1.5-m depth). Results from automated irrigation scheduling were compared to those from manual irrigation based on weekly neutron probe readings. In 2009, results from the Automatic irrigation were mixed; biomass yields in the 55% and 0% treatments, dry grain yields in the 80% and 0% treatments, and WUE in the 80%, 55%, and 0% treatments were not significantly different from those in the corresponding Manual treatments. However, dry grain yields in the 55% and 30% treatments were significantly less than those in the Manual control plots. These differences were due mainly to soil water variability in the beginning of the growing season. This conclusion is reinforced by the fact that IWUE for dry grain yield was not significantly different for 30% and 55% treatments, and was significantly greater for Automatic control at 80%. In 2010, there were no significant differences in biomass, dry grain yield, WUE, or IWUE for irrigation control methods when compared across the same amount treatments. Similar results between irrigation methods for at least the highest irrigation rate (80% of soil water depletion) in 2009 and among all irrigation treatment amounts in 2010 indicate that the CWSI-TT method can be an effective trigger for automatically scheduling either full or deficit irrigations for grain sorghum in a semi-arid region.
BackgroundWhile the requirement for thresholds for testing for mutations in BRCA1/2 is being questioned, they are likely to remain for individuals unaffected by a relevant cancer. It is still useful ...to provide pretesting likelihoods, but models need to take into account tumour pathology.MethodsThe Manchester Scoring System (MSS) is a well-used, simple, paper-based model for assessing carrier probability that already incorporates pathology data. We have used mutation testing data from 4115 unrelated samples from affected non-Jewish individuals alongside tumour pathology to further refine the scoring system.ResultsAdding additional points for high-grade serous ovarian cancer <60 (HGSOC=+2) and adding grade score to those with triple-negative breast cancer, while reducing the score for those with HER2+ breast cancer (−6), resulted in significantly improved sensitivity and minor improvements in specificity to the MSS. Sporadic HGSOC <60 years thus reached a score of 15–19 points within the 10% grouping consistent with the 15/113–13.2% that were identified with a BRCA1/2 pathogenic variant. Validation in a population series of ovarian cancer from Cambridge showed high sensitivity at the 10% threshold 15/17 (88.2%).ConclusionsThe new pathology-adjusted Manchester score MSS3 appears to provide an effective and simple-to-use estimate of the 10% and 20% thresholds for BRCA1/2 likelihood. For unaffected individuals, the 20-point (20%) threshold in their affected first-degree relative can be used to determine eligibility at the 10% threshold.
To measure associations of area-level racial and economic residential segregation with severe maternal morbidity (SMM).
We conducted a retrospective cohort study of births at two Philadelphia ...hospitals between 2018 and 2020 to analyze associations of segregation, quantified using the Index of Concentration at the Extremes (ICE), with SMM. We used stratified multivariable, multilevel, logistic regression models to determine whether associations of ICE with SMM varied by self-identified race or hospital catchment.
Of the 25,979 patients (44.1% Black, 35.8% White), 1381 (5.3%) had SMM (Black 6.1%, White 4.4%). SMM was higher among patients residing outside (6.3%), than inside (5.0%) Philadelphia (P < .001). Overall, ICE was not associated with SMM. However, ICErace (higher proportion of White vs. Black households) was associated with lower odds of SMM among patients residing inside Philadelphia (aOR 0.87, 95% CI: 0.80–0.94) and higher odds outside Philadelphia (aOR 1.12, 95% CI: 0.95–1.31). Moran’s I indicated spatial autocorrelation of SMM overall (P < .001); when stratified, autocorrelation was only evident outside Philadelphia.
Overall, ICE was not associated with SMM. However, higher ICErace was associated with lower odds of SMM among Philadelphia residents. Findings highlight the importance of hospital catchment area and referral patterns in spatial analyses of hospital datasets.
Early observations of Type Ia supernovae (SNe Ia) provide a unique probe of their progenitor systems and explosion physics. Here we report the intermediate Palomar Transient Factory (iPTF) discovery ...of an extraordinarily young SN Ia, iPTF 16abc. By fitting a power law to our early light curve, we infer that first light for the SN, that is, when the SN could have first been detected by our survey, occurred only days before our first detection. In the ∼24 hr after discovery, iPTF 16abc rose by ∼2 mag, featuring a near-linear rise in flux for days. Early spectra show strong C ii absorption, which disappears after ∼7 days. Unlike the extensively observed Type Ia SN 2011fe, the colors of iPTF 16abc are blue and nearly constant in the days after explosion. We show that our early observations of iPTF 16abc cannot be explained by either SN shock breakout and the associated, subsequent cooling or the SN ejecta colliding with a stellar companion. Instead, we argue that the early characteristics of iPTF 16abc, including (i) the rapid, near-linear rise, (ii) the nonevolving blue colors, and (iii) the strong C ii absorption, are the result of either ejecta interaction with nearby, unbound material or vigorous mixing of radioactive 56Ni in the SN ejecta, or a combination of the two. In the next few years, dozens of very young normal SNe Ia will be discovered, and observations similar to those presented here will constrain the white dwarf explosion mechanism.
Several constant-flux filtration experiments for yeast cell suspensions, yeast cell debris, and dodecane-water emulsion were performed at various operating conditions in both flat-sheet and ...tubular-membrane systems. The aim of the paper is two-fold. Firstly the relationship between constant-flux behaviour and membrane fouling is discussed. In some cases constant-flux filtration was realized at a constant transmembrane pressure which was below a critical value. In general constant-flux filtration was obtained with moderately increasing transmembrane pressure, and this approach is shown to have some advantages over normal constant-pressure filtration because it clearly provides for the possibility of avoiding over-fouling and so reduces the severity of fouling. Secondly, the concept of critical flux is introduced. Whilst it has long been recognised that low-pressure microfiltration is much more effective than high-pressure microfiltration, the emphasis in this work is upon the possible existence of a critical flux and the desirability of starting filtration operations at a low flux. The critical-flux hypothesis is that on start-up there exists a flux below which a decline of flux with time does not occur. Equations which may enable identification of the appropriate flux level are included.
Anti-oestrogen therapy, tamoxifen in particular, has revolutionised the treatment of breast cancer. However, the partial agonist activity of tamoxifen is associated with an increased risk of ...endometrial cancer and the acquisition by patients of tamoxifen-resistance. In an attempt overcome these negative aspects of tamoxifen therapy, ‘pure’ anti-oestrogens have been developed and are currently being investigated for the treatment of breast cancer.
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