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Search for invisible decays of a Higgs boson produced through vector boson fusion in proton-proton collisions at root s=13 TeV
No full textA search for invisible decays of a Higgs boson is performed using proton-proton collision data collected with the CMS detector at the LHC in 2016 at a center-of-mass energy root s = 13 TeV, corresponding to an integrated luminosity of 35.9fb(-1). The search targets the production of a Higgs boson via vector boson fusion. The data are found to be in agreement with the background contributions from standard model processes. An observed (expected) upper limit of 0.33(0.25), at 95% confidence level, is placed on the branching fraction of the Higgs boson decay to invisible particles, assuming standard model production rates and a Higgs boson mass of 125.09GeV. Results from a combination of this analysis and other direct searches for invisible decays of the Higgs boson, performed using data collected at root s = 7, 8, and 13 TeV, are presented. An observed (expected) upper limit of 0.19(0.15), at 95% confidence level, is set on the branching fraction of invisible decays of the Higgs boson. The combined limit represents the most stringent bound on the invisible branching fraction of the Higgs boson reported to date. This result is also interpreted in the context of Higgs-portal dark matter models, in which upper bounds are placed on the spin-independent dark-matter-nucleon scattering cross section. (C) 2019 The Author(s). Published by Elsevier B.V
Analytic Formulation of 21 cm Signal from Cosmic Dawn: Ly alpha Fluctuations
No full textWe present an analytic formalism to compute the fluctuating component of the H I signal and extend it to take into account the effects of partial Ly alpha coupling during the era of cosmic dawn. We use excursion set formalism to calculate the size distribution of randomly distributed self-ionized regions. These ionization bubbles are surrounded by partially heated and Ly alpha coupled regions, which create spin temperature T-s fluctuations. We use the ratio of number of Ly alpha to ionizing photons (f(L)) and number of X-ray photons emitted per stellar baryon (N-heat) as modeling parameters. Using our formalism, we compute the global H I signal, its autocorrelation, and its power spectrum in the redshift range 10 <= z <= 30 for the ACDM model. We check the validity of this formalism for various limits and simplified cases. Our results agree reasonably well with existing results from N-body simulations, in spite of following a different approach and requiring orders of magnitude less computation power and time. We further apply our formalism to study the fluctuating component corresponding to the recent observation by the Experiment to Detect the Global Epoch of reionization Signature (EDGES) that shows an unexpectedly deep absorption trough in the global H I signal in the redshift range 15 < z < 19. We show that, generically, the EDGES observation predicts a larger signal in this redshift range but a smaller signal at higher redshifts. We also explore the possibility of negative real-space autocorrelation of spin temperature and show that it can be achieved for partial Ly alpha coupling in many cases corresponding to simplified models and a complete model without density perturbations
Modeling and Analysis of Differential CQI Feedback in 4G/5G OFDM Cellular Systems
No full textReduced feedback schemes are crucial in achieving the high data rates expected of orthogonal frequency-division multiplexing-based 4G and 5G cellular systems. They ensure that the feedback overhead required for acquiring the channel-state information to enable downlink scheduling and adaptive modulation and coding at the base station (BS) does not overwhelm the uplink. We present a novel modeling and analysis of the single-user and multi-user throughputs of the differential feedback scheme that is used in both 4G and 5G standards. In this feedback scheme, a user feeds hack a 4-hit wideband channel quality indicator (CQI), which indicates the rate that the user can decode if the BS was to transmit to it over the entire system bandwidth, and a 2-bit differential CQI for each subband relative to it. Our analysis incorporates co-channel interference, different single-stream multi-antenna modes, and different schedulers, which cover a wide range of the tradeoff between the throughput and user fairness. It brings out several insights such as the increase in the throughput as the correlation between subbands increases and how differential feedback reduces the overhead significantly while only marginally reducing the throughput
A new method to study evaporation of sessile drop from permeable surfaces
No full textReal time monitoring of the mass of an evaporating liquid drop from a real surface by optical methods cannot account for the volume of the drop that gets trapped between asperities. Mass measurement methods do not have high resolution, necessary to account for the small volume of the drop trapped in the pores. This work uses a non resonant mass sensor with a goniometer to simultaneously measure the mass and contact angle of the evaporating drop. Evaporative flux is used as the quantity of comparison across all surfaces. For a pinned sessile drop, the evaporative flux remains almost a constant for any kind of surface. For inkjet printing paper, the negative slope of the flux rate means evaporation is dominant. The drop breaches the hydrophobic coating on the paper to indicate a positive slope of this flux rate. In short, evaporation is strictly controlled by relative humidity and not the nature of the substrate
A Wideband Blocker-Tolerant Receiver With Frequency-Translational Resistive Feedback
No full textThis paper presents a wideband frequency-translational resistive-feedback receiver (RX), operational from 0.1 to 2.2 GHz. Different blocker suppression techniques are proposed to improve both out-of-band (OOB) compression and weakly nonlinear distortion of the RX. The blockers are first rejected at the RX input using an N-path filter. Then, a blocker current cancellation (BCC) technique is used to mitigate the effect of nonlinearity in the transimpedance amplifier. By introducing an auxiliary path in the RX, the OOB linearity of the RX is further improved by means of frequency-translational noise cancellation (FTNC) and split-BCC. The RX prototype fabricated in a 130-nm CMOS process achieves 2.6-3.2-dB noise figure (NF) and tolerates a 0-dBm blocker at a 50-MHz offset with an NF of 4.9 dB. At 40-MHz offset from the local oscillator (LO), the RX exhibits higher +23-dBm out-of-band input-referred inter modulation product of order 3 (OB-IIP3) without FTNC and higher +26 dBm OB-IIP3 with FTNC
High Power Electric Fence Energizer using Standalone PV Generators for Remote Areas
No full textElectric fence play a vital role in the present-day security systems. They are commonly used to protect premises such as buildings, cattle, large farm areas and international borders. As grid supply may not be available in remote areas, diesel generators are mostly used for energizing the fence. But transportation of diesel to remote areas is often expensive and also a difficult task. However, remote areas often have renewable energy sources. This paper proposes a high-power electric fence energizer using standalone PV generators for remote areas. The proposed energizer is based on standalone PV system with battery backup and Marx generator circuit with high gain resonant converter. An energy management system (EMS) has been implemented for efficient operation of the energizer and proper utilization of solar and battery power. The performance of the proposed energizer has been evaluated for different load and source conditions. The proposed fence energizer can be used to cover large fence areas
Plasma/adsorbent system for NOx treatment in diesel exhaust: a case study on solid industrial wastes
No full textFor the past 2 decades, electrical discharge-based non-thermal plasma is being utilized for the treatment of oxides of nitrogen and other hazardous air pollutants at the laboratory level. The discharge plasma exposure mainly results in oxidation of the gaseous pollutants necessitating usage of additional adsorbent/catalytic treatment. In this paper, the possibility of using the solid wastes from industries as a potential adsorbent for reducing oxides of nitrogen from diesel engine exhaust which is pre-treated with plasma discharges (direct plasma)/ozone mixing (indirect plasma) has been studied. Waste from agricultural industry (coffee husk), waste from marine industry (oyster shell), waste from metal casting industry (foundry sand), waste from aluminium extraction (red mud) and waste from thermal power plant (coal fly ash) have been used in this paper to study their gaseous pollutant adsorption capabilities. More than 90% reduction efficiency of oxides of nitrogen has been observed during the study. A comparative analysis of the industrial wastes has been made, and the synergistic effects have been discussed with respect to the plasma treatments. A new dimension to managing solid industrial wastes can be expected as a possible outcome of this work
Scholl reaction of hexaphenylbenzenes with hexakis-alkoxy substituents
No full textThe hexakis-alkoxy substituted hexa-peri-hexabenzocoronene (HBC) discotic core is desirable aiming at strong pi-pi interactions in columns, electronic tuning of the core and better processability. The feasibility of synthesising a new hexakis-alkoxy substituted HBC core is investigated and described in this report. Experimentally, it has been found that when two alkoxy substituents in a peripheral aromatic ring are placed meta to each other, the Scholl reaction results in fully cyclised HBC product. Surprisingly, when the alkoxy groups are ortho to each other, cyclodehydrogenation results in the formation of a partially fused product. This partially-fused ring formation happens under varying reaction conditions and irrespective of the differing alkyl chain lengths. Most plausibly, the considerable strain in the fully fused molecule from 1,2 isomer is the reason to cease the reaction at the partially fused stage. Further quantum-mechanical calculations at the B3LYP/6-31G(d) level of theory also support the hypothesis. The incorporation of two electron donating groups has also reduced the band gap compared to its mono alkoxy analogue. Reduced band gap values are promising feature of these molecules for finding future applications of discotic liquid crystals in organic electronics. GRAPHICS]
Molecular pathways regulated by areca nut in the etiopathogenesis of oral submucous fibrosis
No full textMany oral mucosal lesions are due to substance abuse, such as tobacco and areca nut, amongst others. There is considerable evidence that oral lesions/disorders such as some leukoplakias, most erythroplakias, and submucous fibrosis have malignant potential, with a conversion rate of 5%-10% over a 10-year period. There have been several reports on possible biomarkers that predict malignant conversion of the oral lesions associated with these disorders. Management of these is mostly surgical removal of the lesion followed by observation, and in some cases treatment by antioxidants and anti-inflammatory agents. Oral submucous fibrosis is due to excessive deposition of extracellular matrix in the connective tissue plus, particularly, collagens. The deposition of collagen leads to stiffness of the affected regions and results in difficulty in mouth opening. Areca nut chewing is proposed as the most probable etiological factor in the manifestation of oral submucous fibrosis. Several studies suggest involvement of proinflammatory cytokines, dysregulated by areca nut, in the development of the disease. Amongst these, transforming growth factor-beta is in the forefront, which is also shown to be involved in fibrosis of other organs. This review addresses the molecular mechanisms involved in oral submucous fibrosis development and provides a model for the regulation of transforming growth factor-beta by areca nut. It provides an exemplar of the role of modern molecular techniques in the study of oral disease
Is the predation risk of mate-searching different between the sexes?
No full textIn animals that communicate for pair formation, generally one sex invests more effort in mate searching. Differential predation risk of mate searching between the sexes is hypothesised to determine which sex invests more effort in mate searching. Although searching by males is prevalent in most animals, in orthopteran insects and some other taxa females physically move to localise signalling males who are predominantly sedentary. Although the two sexes thus share mate searching effort in orthopterans, their behavioural strategies are different and sexual selection theory predicts that signalling males may be following the riskier strategy and incurring higher costs. However, relative levels of risk posed by the two mate searching strategies remain largely unexplored. Hence, we estimated the relative predation risk experienced in natural populations by signalling males and responding females. We did this by quantifying predation risk as a probability of mortality in the context of acoustic communication in a tree cricket, Oecanthus henryi from its ecologically relevant predator, a lynx spider, Peucetia viridans. Spiders may perceive calling in males and movement in females by their ability to detect both airborne acoustic cues and substrate-borne vibratory cues. Probability of mortality was quantified by partitioning it into three spatial components at which crickets and spiders interact, using a combination of extensive field observations and manipulative experiments in a semi-natural setup. We found no differences in predation risk faced by calling males and responding females, supporting the prediction that similar sex-specific costs can explain shared mate searching responsibilities. Our findings therefore suggest that direct benefits offered by males to females upon pair formation may better explain shared mate searching effort between the sexes in orthopterans