Nonparametric Transient Classification using Adaptive Wavelets

Classifying transients based on multi band light curves is a challenging but crucial problem in the era of GAIA and LSST since the sheer volume of transients will make spectroscopic classification unfeasible. Here we present a nonparametric classifier that uses the transient's light curve measurements to predict its class given training data. It implements two novel components: the first is the use of the BAGIDIS wavelet methodology - a characterization of functional data using hierarchical wavelet coefficients. The second novelty is the introduction of a ranked probability classifier on the wavelet coefficients that handles both the heteroscedasticity of the data in addition to the potential non-representativity of the training set. The ranked classifier is simple and quick to implement while a major advantage of the BAGIDIS wavelets is that they are translation invariant, hence they do not need the light curves to be aligned to extract features. Further, BAGIDIS is nonparametric so it can be used for blind searches for new objects. We demonstrate the effectiveness of our ranked wavelet classifier against the well-tested Supernova Photometric Classification Challenge dataset in which the challenge is to correctly classify light curves as Type Ia or non-Ia supernovae. We train our ranked probability classifier on the spectroscopically-confirmed subsample (which is not representative) and show that it gives good results for all supernova with observed light curve timespans greater than 100 days (roughly 55% of the dataset). For such data, we obtain a Ia efficiency of 80.5% and a purity of 82.4% yielding a highly competitive score of 0.49 whilst implementing a truly "model-blind" approach to supernova classification. Consequently this approach may be particularly suitable for the classification of astronomical transients in the era of large synoptic sky surveys.Comment: 14 pages, 8 figures. Published in MNRA

Towards the Future of Supernova Cosmology

For future surveys, spectroscopic follow-up for all supernovae will be extremely difficult. However, one can use light curve fitters, to obtain the probability that an object is a Type Ia. One may consider applying a probability cut to the data, but we show that the resulting non-Ia contamination can lead to biases in the estimation of cosmological parameters. A different method, which allows the use of the full dataset and results in unbiased cosmological parameter estimation, is Bayesian Estimation Applied to Multiple Species (BEAMS). BEAMS is a Bayesian approach to the problem which includes the uncertainty in the types in the evaluation of the posterior. Here we outline the theory of BEAMS and demonstrate its effectiveness using both simulated datasets and SDSS-II data. We also show that it is possible to use BEAMS if the data are correlated, by introducing a numerical marginalisation over the types of the objects. This is largely a pedagogical introduction to BEAMS with references to the main BEAMS papers.Comment: Replaced under married name Lochner (formally Knights). 3 pages, 2 figures. To appear in the Proceedings of 13th Marcel Grossmann Meeting (MG13), Stockholm, Sweden, 1-7 July 201

Extending BEAMS to incorporate correlated systematic uncertainties

New supernova surveys such as the Dark Energy Survey, Pan-STARRS and the LSST will produce an unprecedented number of photometric supernova candidates, most with no spectroscopic data. Avoiding biases in cosmological parameters due to the resulting inevitable contamination from non-Ia supernovae can be achieved with the BEAMS formalism, allowing for fully photometric supernova cosmology studies. Here we extend BEAMS to deal with the case in which the supernovae are correlated by systematic uncertainties. The analytical form of the full BEAMS posterior requires evaluating 2^N terms, where N is the number of supernova candidates. This `exponential catastrophe' is computationally unfeasible even for N of order 100. We circumvent the exponential catastrophe by marginalising numerically instead of analytically over the possible supernova types: we augment the cosmological parameters with nuisance parameters describing the covariance matrix and the types of all the supernovae, \tau_i, that we include in our MCMC analysis. We show that this method deals well even with large, unknown systematic uncertainties without a major increase in computational time, whereas ignoring the correlations can lead to significant biases and incorrect credible contours. We then compare the numerical marginalisation technique with a perturbative expansion of the posterior based on the insight that future surveys will have exquisite light curves and hence the probability that a given candidate is a Type Ia will be close to unity or zero, for most objects. Although this perturbative approach changes computation of the posterior from a 2^N problem into an N^2 or N^3 one, we show that it leads to biases in general through a small number of misclassifications, implying that numerical marginalisation is superior.Comment: Resubmitted under married name Lochner (formally Knights). Version 3: major changes, including a large scale analysis with thousands of MCMC chains. Matches version published in JCAP. 23 pages, 8 figure

RETROSPECTIVE STUDY ON ASSESSMENT OF FACTORS ASSOCIATED WITH HYSTERECTOMIZED PATIENTS

ABSTRACTObjective: The study was carried out to determine the age pattern, indications, risk factors, co-morbid conditions, type of surgery, and the associatedcomplications of hysterectomized patients.Methods: A cross-sectional, retrospective study was done over a period of 8-month. A total of 150 hysterectomies were documented.Results: All data collected were analyzed and in this 111 hysterectomies (74%) were done by vaginal route and 39 (26%) done abdominally. In which,50.60% hysterectomized patients were in the age group 40-50 years and 32% patients were in 50-60 years. Out 111 vaginal hysterectomy (VH), 79 arelaparoscopic-assisted VH. Fibroid (33.33%) and dysfunctional uterine bleeding (DUB) (17%) were the most common indication. Complications wereinjuries to the bladder in 5 patients, 4 wound sepsis, 2 chronic cervicitis, 1 menopausal symptoms, 1 thrombocytosis, bilateral mild hydronephrosisin 1,and right ovarian cyst in 1 patient. This study also recorded the common co-morbid medical conditions in women undergoing hysterectomies includediabetes mellitus, 30.66%; hypertension, 23.33%; hypothyroid, 19.33%; dyslipidemia, 12%.Conclusion: The present study shows that the most common method performed is VH. Fibroid and DUB are very common indications for undergoinghysterectomy; of these, most of the hysterectomized patients were in the age group of 40-50 years. Laparoscopic hysterectomy may be an alternativeto abdominal hysterectomy for those patients in whom a VH is not indicated. All women should be carefully evaluated before surgery, and its route isdecided.Keywords: Hysterectomy, Fibroid, Dysfunctional uterine bleeding, Complications

Recognition of Interaction Interface Residues in Low-Resolution Structures of Protein Assemblies Solely from the Positions of Cα Atoms

Background: The number of available structures of large multi-protein assemblies is quite small. Such structures provide phenomenal insights on the organization, mechanism of formation and functional properties of the assembly. Hence detailed analysis of such structures is highly rewarding. However, the common problem in such analyses is the low resolution of these structures. In the recent times a number of attempts that combine low resolution cryo-EM data with higher resolution structures determined using X-ray analysis or NMR or generated using comparative modeling have been reported. Even in such attempts the best result one arrives at is the very course idea about the assembly structure in terms of trace of the C alpha atoms which are modeled with modest accuracy. Methodology/Principal Findings: In this paper first we present an objective approach to identify potentially solvent exposed and buried residues solely from the position of C alpha atoms and amino acid sequence using residue type-dependent thresholds for accessible surface areas of C alpha. We extend the method further to recognize potential protein-protein interface residues. Conclusion/Significance: Our approach to identify buried and exposed residues solely from the positions of C alpha atoms resulted in an accuracy of 84%, sensitivity of 83-89% and specificity of 67-94% while recognition of interfacial residues corresponded to an accuracy of 94%, sensitivity of 70-96% and specificity of 58-94%. Interestingly, detailed analysis of cases of mismatch between recognition of interface residues from C alpha positions and all-atom models suggested that, recognition of interfacial residues using C alpha atoms only correspond better with intuitive notion of what is an interfacial residue. Our method should be useful in the objective analysis of structures of protein assemblies when positions of only C alpha positions are available as, for example, in the cases of integration of cryo-EM data and high resolution structures of the components of the assembly

Does patellar tilt affect the outcome of total knee arthroplasty? a retrospective study

Background: Patellofemoral joint management during total knee replacement remains a controversial topic among knee surgeons. The purpose of this study is to evaluate the influence of resurfaced patellar component tilt on the functional outcome of total knee arthroplasty.Methods: This is a retrospective study reviewing all the patients who underwent total knee arthroplasty in our institution, operated by a single surgeon using a single implant design.Results: A total of 48 patients and 82 knees were enrolled into this study. Patients were evaluated by Oxford knee score, knee society score, Melbourne patellar score, anteroposterior, lateral, and Merchant’s view radiographs. The patellar tilt was divided into three grades according the measurement obtained from knee radiographs.Conclusions: A higher degree of patella tilt (more than 10 degree) is associated with poor outcome following total knee arthroplasty. Melbourne patella score is more sensitive than knee society score and Oxford score in assessing the effect of patella tilt on the outcome of total knee arthroplasty

The variability of sagittal spino-pelvic mobility in Indian population

Background: Abnormal spino-pelvic mobility is increasingly recognized as a leading cause for hip instability following arthroplasty.Methods: We studied the lateral spino-pelvic radiographs of 90 patients, with no spine/hip pathology in standing and sitting positions. We measured the change in sacral slope and grouped them into three spino-pelvic patterns.Results: We found that 50% of study subjects had normal spino-pelvic mobility. The remaining 50% were either hypermobile (24%) or stiff (26%). The stiff spines were either fixed (11%) or hypomobile (15%).Conclusions: Our study shows that in a normal population without any prior hip/spine pathology a significant percentage (50%) have abnormal spino-pelvic mobility. The significance of spinal stiffness in younger age group need to be looked further to make any changes in acetabular cup placement during hip replacement

In the Absence of Frazzled Over-Expression of Abelson Tyrosine Kinase Disrupts Commissure Formation and Causes Axons to Leave the Embryonic CNS

BACKGROUND: In the Drosophila embryonic nerve cord, the formation of commissures require both the chemoattractive Netrin receptor Frazzled (Fra) and the Abelson (Abl) cytoplasmic tyrosine kinase. Abl binds to the cytoplasmic domain of Fra and loss-of-function mutations in abl enhance fra-dependent commissural defects. To further test Abl's role in attractive signaling, we over-expressed Abl in Fra mutants anticipating rescue of commissures. METHODOLOGY/PRINCIPAL FINDINGS: The Gal4-UAS system was used to pan-neurally over-express Abl in homozygous fra embryos. Surprisingly, this led to a significant decrease in both posterior and anterior commissure formation and induced some commissural and longitudinal axons to project beyond the CNS/PNS border. Re-expressing wild-type Fra, or Fra mutants with a P-motif deleted, revert both commissural and exiting phenotypes, indicating that Fra is required but not a specific P-motif. This is supported by S2 cell experiments demonstrating that Abl binds to Fra independent of any specific P-motif and that Fra continues to be phosphorylated when individual P-motifs are removed. Decreasing midline repulsion by reducing Robo signaling had no effect on the Abl phenotype and the phenotypes still occur in a Netrin mutant. Pan-neural over-expression of activated Rac or Cdc42 in a fra mutant also induced a significant loss in commissures, but axons did not exit the CNS. CONCLUSION/SIGNIFICANCE: Taken together, these data suggest that Fra activity is required to correctly regulate Abl-dependent cytoskeletal dynamics underlying commissure formation. In the absence of Fra, increased Abl activity appears to be incorrectly utilized downstream of other guidance receptors resulting in a loss of commissures and the abnormal projections of some axons beyond the CNS/PNS border