Reporting a new ciliate, Hemiurosomoida linea n.sp. from a freshwater pond of Rajghat, Delhi, India

Hemiurosomoida was established as a new genus by Singh and Kamra in 2015 based on its morphology, morphogenesis and molecular analysis. Based on their morphology, the members of this genus were earlier erroneously placed in the genus Oxytricha, then shifted to another genus Urosomoida, before establishing the new genus Hemiurosomoida. However, a detailed molecular analysis based on small subunit ribosomal RNA (SSU rRNA) showed that the members of this genus are rather placed far apart from the other two genera in the phylogenetic tree. Therefore, they are now placed in a new genus Hemiurosomoida. To date, four species of this genus have been reported, viz. H. longa, H. warreni, H. tibetensis and H. koreana. In the present investigation, a new freshwater species, Hemiurosomoida linea n. sp. was reported from a freshwater pond located in Rajghat, Delhi, India. Diagnostic features of H. linea include- a flexible body with an average size of 81x18 µm (protargol stained cells); narrowly elongated cells with a rounded anterior end and a tapering posterior end; the presence of 2 macronuclear nodules and 2 micronuclei; the presence of only 17 Frontal-Ventral-Transverse (F1-8, V1-5, T1-4) cirri, the transverse cirri (T1-4) being arranged in a linear row; four dorsal rows of bristles (DK1-3 and DM1); 2 caudal cirri; an average of 19 adoral membranelles; 17 right marginal and 17 left marginal cirri; no fragmentation of DP3; a flat and narrow buccal cavity, and undulating membranes (UMs) in typical Oxytricha pattern. Thus, this study has unravelled and confirmed that H. linea was a new species and helped expand the knowledge base of ciliate biodiversity in India.  

A framework of secured and bio-inspired image steganography using chaotic encryption with genetic algorithm optimization (CEGAO)

The two key issues related to steganography techniques are, statistical undetectability and picture quality. Image steganography takes the advantage of limited power of Human Visual System (HVS). The proposed framework offers an approach of secure data hiding technique in digital images. Novel scheme presented encrypts meaningful secret data using nonlinear dynamics (chaos theory) before embedding into host or cover image. A basic LSB embedding method is used for encrypting data into cover image. Genetic Algorithm based pixel adjustment process is used to reduce the difference of error between the host image and its stego version with low distortions. The results of proposed scheme are compared with other steganographic algorithm using Peak Signal to Noise Ratio (PSNR) and Structural Similarity (SSIM) index, color frequency test and StirMark analysis

Measurement of the cross section for isolated-photon plus jet production in pp collisions at √s=13 TeV using the ATLAS detector

The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb−1. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- algorithm with radius parameter and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon–jet invariant mass and the scattering angle in the photon–jet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements

Search for the production of single vector-like and excited quarks in the Wt final state in pp collisions at √s=8 TeV with the ATLAS detector

A search for vector-like quarks and excited quarks in events containing a top quark and a W boson in the final state is reported here. The search is based on 20.3 fb−1 of proton-proton collision data taken at the LHC at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector. Events with one or two leptons, and one, two or three jets are selected with the additional requirement that at least one jet contains a b-quark. Single-lepton events are also required to contain at least one large-radius jet from the hadronic decay of a high-pTW boson or a top quark. No significant excess over the expected background is observed and upper limits on the cross-section times branching ratio for different vector-like quark and excited-quark model masses are derived. For the excited-quark production and decay to Wt with unit couplings, quarks with masses below 1500 GeV are excluded and coupling-dependent limits are set

A search for resonances decaying into a Higgs boson and a new particle X in the XH → qqbb final state with the ATLAS detector

A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb−1 of proton–proton collision data at collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle X is assumed to decay to a pair of light quarks, and the fully hadronic final state is analysed. The search considers the regime of high XH resonance masses, where the X and H bosons are both highly Lorentz-boosted and are each reconstructed using a single jet with large radius parameter. A two-dimensional phase space of XH mass versus X mass is scanned for evidence of a signal, over a range of XH resonance mass values between 1 TeV and 4 TeV, and for X particles with masses from 50 GeV to 1000 GeV. All search results are consistent with the expectations for the background due to Standard Model processes, and 95% CL upper limits are set, as a function of XH and X masses, on the production cross-section of the resonance

Search for invisible Higgs boson decays in vector boson fusion at √s = 13 TeV with the ATLAS detector

We report a search for Higgs bosons that are produced via vector boson fusion and subsequently decay into invisible particles. The experimental signature is an energetic jet pair with invariant mass of O(1) TeV and O(100) GeV missing transverse momentum. The analysis uses 36.1 fb−1 of pp collision data at √s=13 TeV recorded by the ATLAS detector at the LHC. In the signal region the 2252 observed events are consistent with the background estimation. Assuming a 125 GeV scalar particle with Standard Model cross sections, the upper limit on the branching fraction of the Higgs boson decay into invisible particles is 0.37 at 95% confidence level where 0.28 was expected. This limit is interpreted in Higgs portal models to set bounds on the wimp–nucleon scattering cross section. We also consider invisible decays of additional scalar bosons with masses up to 3 TeV for which the upper limits on the cross section times branching fraction are in the range of 0.3–1.7 pb

Observation of photon-induced W⁺W⁻ production in pp collisions at √s=13 TeV using the ATLAS detector

This letter reports the observation of photon-induced production of W-boson pairs, γγ→ WW. The analysis uses 139 fb-1 of LHC proton-proton collision data taken at √s=13 TeV recorded by the ATLAS experiment during the years 2015-2018. The measurement is performed selecting one electron and one muon, corresponding to the decay of the diboson system as WW→e±νμ∓ν final state. The background-only hypothesis is rejected with a significance of well above 5 standard deviations consistent with the expectation from Monte Carlo simulation. A cross section for the γγ→ WW process of 3.13±0.31(stat.)±0.28(syst.) fb is measured in a fiducial volume close to the acceptance of the detector, by requiring an electron and a muon of opposite signs with large dilepton transverse momentum and exactly zero additional charged particles. This is found to be in agreement with the Standard Model prediction