Applications of a semi-dynamic convex hull algorithm

We obtain new results for manipulating and searching semi-dynamic planar convex hulls (subject to deletions only), and apply them to derive improved bounds for two problems in geometry and scheduling. The new convex hull results are logarithmic time bounds for set splitting and for finding a tangent when the two convex hulls are not linearly separated. Using these results, we solve the following two problems optimally inO(n logn) time: (1) [matching] givenn red points andn blue points in the plane, find a matching of red and blue points (by line segments) in which no two edges cross, and (2) [scheduling] givenn jobs with due dates, linear penalties for late completion, and a single machine on which to process them, find a schedule of jobs that minimizes the maximum penalty.     

Dynamic SIMS ion microscopy imaging of individual bacterial cells for studies of isotopically labeled molecules

A CAMECA IMS-3f SIMS ion microscope instrument capable of 500 nm spatial resolution was used for imaging single bacterial cells in the soil treated with ¹³C-labeled phenol in desired treatments. After formaldehyde fixation, the soil samples containing bacterial cells were smeared on the silicon substrate. The O₂⁺ primary ion beam was used for the detection of negative secondary ions. Images of individual bacterial cells were recorded on a CCD camera in masses 24, 25, 26, and 27 signals. The respective mass images represented contributions from the molecular ions of interest, for example ²⁴(¹²C₂)⁻, ²⁵(¹³C¹²C)⁻, ²⁶(¹²C¹⁴N)⁻, ²⁷(¹³C¹⁴N)⁻, as well as interfering mass species associated with a particular mass. However, in cells treated with ¹³C-labeled phenol the enhancement of signals in masses 25 and 27 images due to increased signals of ²⁵(¹³C¹²C)⁻ and ²⁷(¹³C¹⁴N)⁻, respectively, unequivocally indicated the presence of ¹³C-labeled phenol in bacterial cells in direct comparison to the samples treated only with unlabeled phenol. The ratio images of masses 25/24 and 27/26 from individual cells revealed a cell-to-cell heterogeneity in the labeling with ¹³C-phenol. This study indicates that the ion microscope can be applied effectively for studies of labeled molecules in microbiology and biogeochemistry.     

Off-Line Maintenance of Planar Configurations

We achieve anO(log n) amortized time bound per operation for the off-line version of the dynamic convex hull problem in the plane. In this problem, a sequence ofninsert,delete, andqueryinstructions are to be processed, where each insert instruction adds a new point to the set, each delete instruction removes an existing point, and each query requests a standard convex hull search. We process the entire sequence in totalO(n log n) time andO(n) space. Alternatively, we can preprocess a sequence ofninsertions and deletions inO(n log n) time and space, then answer queries in history inO(log n) time apiece (a query in history means a query comes with a time parametert, and it must be answered with respect to the convex hull present at timet). The same bounds also hold for the off-line maintenance of several related structures, such as the maximal vectors, the intersection of half-planes, and the kernel of a polygon. Achieving anO(log n) per-operation time bound for theon-lineversions of these problems is a longstanding open problem in computational geometry.     

EGFRisopred: a machine learning-based classification model for identifying isoform-specific inhibitors against EGFR and HER2

The EGFR kinase pathway is one of the most frequently activated signaling pathways in human cancers. EGFR and HER2 are the two significant members of this pathway, which are attractive drug targets of clinical relevance in lung and breast cancer. Therefore, identifying EGFR- and HER2-specific inhibitors is one of the important challenges in cancer drug discovery. To address this issue, a dataset of 519 compounds having inhibitory activity against both the isoforms, i.e., EGFR and HER2, was collected from the literature and developed a knowledge-based computational classification model for predicting the specificity of a molecule for an isoform (EGFR/HER2) with precision. A total of seventy-two classification models using nine fingerprint types, four classifiers (IBK, NB, SMO and RF) and two different datasets (EGFR and HER2 isoform specific) were developed. It was observed that the models developed using random forest and IBK performed better for EGFR- and HER2-specific datasets, respectively. Scaffold and functional group analysis led to the identification of prevalent core and fragments in each of the datasets. The accuracy of the selected best performing models was also evaluated using the decoy dataset. We have also developed an application EGFRisopred, which integrates the best performing models and permits the user to predict the specificity of a compound as an EGFR-/HER2-specific anticancer agent. It is expected that the tool’s availability as a free utility will allow researchers to identify new inhibitors against these targets important in cancer.

Graphic abstract

     

Ionic liquid as reagent. A green procedure for the regioselective conversion of epoxides to vicinal-halohydrins using [AcMIm]X under catalyst- and solvent-free conditions

A variety of structurally diverse epoxides undergo facile cleavages by ionic liquid, [AcMIm]X without any catalyst and solvent to produce the corresponding vicinal halohydrins in high yields. The cleavages are considerably fast and highly regioselective.     

Natural left-right symmetry,atomic parity experiments and asymmetries in high energy e+e− collisions in petra and pep regions

The previously proposed left-right-symmetric SU(2)_L × SU(2)_R × U(1) theory permits one of the two neutral gauge particles N₁ and N₂ to be particularly light (<mW⁺_L) compatible with all neutrin-data and the present atomic parity experiments. Distinguishing features of this theory (with the light mass solution) for e^?e⁺ → μ⁺μ^? and π⁺π^? at PETRA and PEP energies as compared to the SU(2) × U(1) predictions are given.     

Elektronenmikroskopische Studie an mittels Plasma (Ionen) ange?tzten Polymeren

Ohne Zusammenfassung     

Measurement of absolute rate data for the reaction of ground state atomic silicon,Si(33PJ), with halogenated olefinic and aromatic compounds by time-resolved atomic resonance absorption spectroscopy

We present a kinetic study of the reaction of ground state silicon atoms with halogenated unsaturated organic compounds (R). Si(3³P_J) was generated by the repetitive pulsed irradiation of SiCl₄ in the presence of excess helium buffer gas and the reactant R in a slow flow system, kinetically equivalent to a static system. The ground state atom was monitored by time-resolved atomic resonance absorption spectroscopy at λ = 252 nm [Si(4³P_J) ← Si(3³P_J)] on time scales by which the optically metastable tates,Si(3¹D₂) and Si(3¹S₀) had relaxed to the ³P state, using signal averaging methods. Computerized fitting of the resulting atomic decay traces in the presence of the various reactants, R, yielded the following new body of absolute second-order rate constants (k_R, T = 300 K, errors = 2sigma;):

Online Scheduling with Hard Deadlines

We study non-preemptive, online admission control in the hard deadline model: each job must either be serviced prior to its deadline or be rejected. Our setting consists of a single resource that services an online sequence of jobs; each job has a length indicating the length of time for which it needs the resource and a delay indicating the maximum time it can wait for the service to be started. The goal is to maximize total resource utilization. The jobs are non-preemptive and exclusive, meaning once a job begins, it runs to completion, and at most one job can use the resource at any time. We obtain a series of results, under varying assumptions of job lengths and delays.