KMSubtraction: Reconstruction of unreported subgroup survival data utilizing published Kaplan-Meier survival curves

ABSTRACTBACKGROUNDData from certain subgroups of clinical interest may not be presented in primary manuscripts or conference abstract presentations. In an effort to enable secondary data analyses, we propose a workflow to retrieve unreported subgroup survival data from published Kaplan-Meier (KM) curves.METHODSWe developed KMSubtraction, an R-package that retrieves patients from unreported subgroups by matching participants on KM curves of the overall cohort to participants on KM curves of a known subgroup with follow-up time. By excluding matched patients, the opposing unreported subgroup may be retrieved. Reproducibility and limits of error of the KMSubtraction workflow were assessed by comparing unmatched patients against the original survival data of subgroups from published datasets and simulations. Monte Carlo simulations were utilized to evaluate the effect of the reported subgroup proportion, missing data, censorship proportion in the overall and subgroup cohort, sample size and number-at-risk table intervals on the limits of error of KMSubtraction. 3 matching algorithms were explored – minimal cost bipartite matching, Mahalanobis distance matching, and nearest neighbor matching by logistic regression.RESULTSThe validation exercise found no material systematic error and demonstrates the robustness of KMSubtraction in deriving unreported subgroup survival data. Limits of error were small and negligible on marginal Cox proportional hazard models comparing reconstructed and original survival data of unreported subgroups. Extensive Monte Carlo simulations demonstrate that datasets with high reported subgroup proportion (r=0.467, p<0.001), small dataset size (r=-0.374, p<0.001) and high proportion of missing data in the unreported subgroup (r=0.553, p<0.001) were associated with uncertainty are likely to yield high limits of error with KMSubtraction.CONCLUSIONWhile KMSubtraction demonstrates robustness in deriving survival data from unreported subgroups, the implementation of KMSubtraction should take into consideration the aforementioned limitations. The limits of error of KMSubtraction, as reflected by the mean |ln(HR)| from converged Monte Carlo simulations may guide the interpretation of reconstructed survival data of unreported subgroups.

Meridian convergence: An alternate methodology

This study investigates the development and testing of an approximation method for the Mine Surveyor to calculate meridian convergence. This study, a detailed review of experimental techniques, follows a statistical experimental approach to establish how accurate an alternative method performs against traditional methods of meridian convergence calculation used by the Mine Surveyor. The spatial study is defined by the geographical range of the existing Schreiber Geodetic Tables, ranging from 70 km south of Ndola (Zambia) to 10 km north of De Aar (South Africa). The sample size is established under the constraint of an infinite population. Linear regression in collaboration with the hold-out validation technique is adopted to statistically refine the alternative method of calculation. The computational outcomes of the refined alternative method in comparison to the unrefined method are predominantly closer to the traditional outcomes. Computational outcomes specific to the hold-out validation set demonstrate a maximum sub-{1^{\prime\prime }} variance of {0.650^{\prime\prime }}. A sub-variance of {0.650^{\prime\prime }} satisfies the South African Mine Survey limits of error. The subsequent clustering of variances at specific variance intervals are similar to comparative studies conducted by T. Soler and R.J. Fury with respect to meridian convergence.

Continuous Monitoring of Respiratory Rate in Emergency Admissions: Evaluation of the RespiraSense™ Sensor in Acute Care Compared to the Industry Standard and Gold Standard

Respiratory Rate (RR) is the best marker to indicate deterioration but measurement are often inaccurate. The RespiraSense™ is a non-invasive, wireless, body worn, motion-tolerant and continuous respiratory rate monitor. We aimed to determine whether the performance of RespiraSense™ was equivalent to that of a gold standard measurement technique of capnography and the industry standard of manual counts. RespiraSense™ measures respiratory rate and transmit signals wirelessly to a tablet device. We measured respiratory rate in 24 emergency admissions to an Acute Medical Unit in the UK. Patients were observed for two hours. Manual counts were undertaken every 15 min and compared to measurements with capnography and RespiraSense™. Data from 17 patients admitted as medical emergencies was evaluated. For measurements obtained at rest a mean RR of 19.3 (SD 4.89) for manual measurements compared to mean RR of 20.2 (SD 4.54) for measurements obtained with capnography and mean RR of 19.8 (SD 4.52) with RespiraSense™. At rest, RespiraSense™ has a bias of 0.38 and limits of agreement of 1.0 to 1.8 bpm, when compared to the capnography derived RR. Measurements were within pre-defined limits of error at rest. Continuous measurement of RR with RespiraSense™ in patients admitted as acute emergencies is both feasible and reliable.

Ефективність застосування регулятора росту «Хлормекват-хлорид» у посівах пшениці озимої залежно від рівня удобрення

Наведено результати трирічних досліджень впливу регулятора росту «Хлормекват-хлорид» у поєднанні з дією трьох варіантів удобрення ґрунту на ріст, розвиток і формування урожаю зерна пшеницею озимою сорту Співанка в разі вирощування її на чорноземі звичайному. Найбільш ефективними варі-антами застосування «Хлормекват-хлориду» виявились: обробка посівів цим регулятором росту восени і одноразова обробка навесні, обробка посівів регулятором росту восени і дворазова обробка навесні. Інкрустація насіння «Хлормекват-хлоридом» перед сівбою, а також інкрустація з одноразовою обробкою посівів навесні теж позитивно впливали на формування урожаю зерна. Встановлено найоптимальнішу доза добрив для ефективного застосування «Хлормекват-хлориду». The improvement of technology of growing of winter wheat allows to realize reserve of increase of her productivity. The aim of these researches was establishment of efficiency of complex application of treatment of seed or sowing of winter wheat of sort Spivanka by the growth regulator «Chlormequate-chloride» and different norms of fertilizer of soil by mineral fertilizers (N60Р90К60+N30+N30, N30Р60К30+N30, Р30К20+N30) on a growth, development and forming of harvest of grain at growing on black earth ordinary in the conditions of North Steppe. Treatment of seed or sowing of winter wheat influenced «Chlormequate-chloride» on growth, development and forming of harvest of grain during a spring-summer vegetation at application of all variants of fertilizer of soil. The higher level of harvest is got on a background the most (N60Р90К60+N30+N30) and middle (N30Р60К30+N30) dose of fertilizers. Application of different variants of treatment of «Chlormequate-chloride» provided the increase of harvest of grain of winter wheat within the limits of 3.4–11.6 %. We appeared the most effective variants of application of «Chlormequate-chloride»: treatment of growth regulator in autumn and one or double treatment in spring. Encrustation of seed by «Chlormequate-chloride» influenced positively on forming of harvest of grain of winter wheat also. Difference between variants with one or double treatment by «Chlormequate-chloride» additionally to treatment of sowing in autumn appeared insignificant (within the limits of error of experience). Application of an increase dose of fertilizers (N60Р90К60+N30+N30) in combination with the different variants of treatment of growth regulator did not provide the considerable increase of harvest of grain of winter wheat (on the average of all variants of experience for all years researches it hesitated within the limits of 2.5–4.7 %). At growing of wheat the fertilizer of soil appeared more effective by the dose of fertilizers of N30Р60К30+N30.

Systematic crystallographic refinement of triclinic unit cells

Combining the exhaustive indexing of triclinic powder diffraction patterns with a crystallographic determination of unit cell parameters from pinacoid and prism reflections yields unit cell parameters with realistic limits of error. Additionally a referee method has been developed by which the six reciprocal cell parameters of a triclinic phase are determined by solving an exhaustive set of linear simultaneous equations in six unknowns.

Problems with Radiometric “Time”: Dating the Initial Human Colonization of Sahul

Until recently, the only chronometric technique applied to Sahulian archaeological sites was14C dating; the ages obtained rarely exceeded 40,000 bp. Belief that the region was first colonized around that time has recently been shaken by luminescence dates from several archaeological sites in northern Australia that suggest people arrived between 60,000 and 55,000 bp. The ensuing debate over their validity revealed that some participants misunderstood luminescence dating and the temporal limitations of14C dating, illustrated here through a discussion of thetempoandmodeof Sahulian colonization. Radiometric techniques cannot distinguish between the models proposed because they are unable to resolve temporal issues that occur within their limits of error.