Cochin University of Science and Technology

BACKGROUND: Patent foramen ovale and atrial septal aneurysm have been identified as potential risk factors for stroke, but information about their effect on the risk of recurrent stroke is limited. We studied the risks of recurrent cerebrovascular events associated with these cardiac abnormalities. METHODS: A total of 581 patients (age, 18 to 55 years) who had had an ischemic stroke of unknown origin within the preceding three months were consecutively enrolled at 30 neurology departments. All patients received aspirin (300 mg per day) for secondary prevention. RESULTS: After four years, the risk of recurrent stroke was 2.3 percent (95 percent confidence interval, 0.3 to 4.3 percent) among the patients with patent foramen ovale alone, 15.2 percent (95 percent confidence interval, 1.8 to 28.6 percent) among the patients with both patent foramen ovale and atrial septal aneurysm, and 4.2 percent (95 percent confidence interval, 1.8 to 6.6 percent) among the patients with neither of these cardiac abnormalities. There were no recurrences among the patients with an atrial septal aneurysm alone. The presence of both cardiac abnormalities was a significant predictor of an increased risk of recurrent stroke (hazard ratio for the comparison with the absence of these abnormalities, 4.17; 95 percent confidence interval, 1.47 to 11.84), whereas isolated patent foramen ovale, whether small or large, was not. CONCLUSIONS: Patients with both patent foramen ovale and atrial septal aneurysm who have had a stroke constitute a subgroup at substantial risk for recurrent stroke, and preventive strategies other than aspirin should be considered.

Antimicrobial resistance (AMR) is a serious threat to global public health, but obtaining representative data on AMR for healthy human populations is difficult. Here, we use metagenomic analysis of untreated sewage to characterize the bacterial resistome from 79 sites in 60 countries. We find systematic differences in abundance and diversity of AMR genes between Europe/North-America/Oceania and Africa/Asia/South-America. Antimicrobial use data and bacterial taxonomy only explains a minor part of the AMR variation that we observe. We find no evidence for cross-selection between antimicrobial classes, or for effect of air travel between sites. However, AMR gene abundance strongly correlates with socio-economic, health and environmental factors, which we use to predict AMR gene abundances in all countries in the world. Our findings suggest that global AMR gene diversity and abundance vary by region, and that improving sanitation and health could potentially limit the global burden of AMR. We propose metagenomic analysis of sewage as an ethically acceptable and economically feasible approach for continuous global surveillance and prediction of AMR.

Socioeconomic challenges continue to mount for half a billion residents of central India because of a decline in the total rainfall and a concurrent rise in the magnitude and frequency of extreme rainfall events. Alongside a weakening monsoon circulation, the locally available moisture and the frequency of moisture-laden depressions from the Bay of Bengal have also declined. Here we show that despite these negative trends, there is a threefold increase in widespread extreme rain events over central India during 1950-2015. The rise in these events is due to an increasing variability of the low-level monsoon westerlies over the Arabian Sea, driving surges of moisture supply, leading to extreme rainfall episodes across the entire central subcontinent. The homogeneity of these severe weather events and their association with the ocean temperatures underscores the potential predictability of these events by two-to-three weeks, which offers hope in mitigating their catastrophic impact on life, agriculture and property.Against the backdrop of a declining monsoon, the number of extreme rain events is on the rise over central India. Here the authors identify a threefold increase in widespread extreme rains over the region during 1950-2015, driven by an increasing variability of the low-level westerlies over the Arabian Sea.

This paper presents the results from an experimental program and an analytical assessment of the influence of addition of fibers on mechanical properties of concrete. Models derived based on the regression analysis of 60 test data for various mechanical properties of steel fiber-reinforced concrete have been presented. The various strength properties studied are cube and cylinder compressive strength, split tensile strength, modulus of rupture and postcracking performance, modulus of elasticity, Poisson’s ratio, and strain corresponding to peak compressive stress. The variables considered are grade of concrete, namely, normal strength (35MPa) , moderately high strength (65MPa) , and high-strength concrete (85MPa) , and the volume fraction of the fiber ( Vf=0.0 , 0.5, 1.0, and 1.5%). The strength of steel fiber-reinforced concrete predicted using the proposed models have been compared with the test data from the present study and with various other test data reported in the literature. The proposed model predicted the test data quite accurately. The study indicates that the fiber matrix interaction contributes significantly to enhancement of mechanical properties caused by the introduction of fibers, which is at variance with both existing models and formulations based on the law of mixtures.

Global production and consumption of poly(ethylene terephthalate) (PET) products has increased dramatically over the past few decades. World consumption of PET has exceeded 13 million tonnes, of which about 1.5 million tonnes is exclusively consumed by the packaging sector itself. However, this tremendous increase in PET consumption has resulted in the accumulation of an enormous quantity of waste, the disposal of which is complex day by day. Among different PET recycling methods, chemical recycling (chemolysis) is the most successful method to convert PET into its monomers/oligomers. This review presents in detail recent developments in the chemical recycling (glycolysis and aminolysis) of PET. The wide spectrum of depolymerizing agents used, the reaction conditions, catalysts, products of depolymerization, and their potential applications are described.

Concrete made using geopolymer technology is environmental friendly and could be considered as part of the sustainable development. Even though aggregate constitutes major volume in geopolymer concrete, only limited study related to this parameter has been reported. This paper presents the summary of study carried out to understand the influence of aggregate content on the engineering properties of geopolymer concrete. Influence of other parameters on engineering properties of geopolymer concrete such as curing temperature, period of curing, ratio of sodium silicate to sodium hydroxide, ratio of alkali to fly ash and molarity of sodium hydroxide are also discussed in this paper. Based on the study carried out, it could be concluded that a geopolymer concrete with proper proportioning of total aggregate content and ratio of fine aggregate to total aggregate, along with the optimum values of other parameters, can have better engineering properties than the corresponding properties of ordinary cement concrete.

Magnetite nanoparticles synthesized in the laboratory were used for the removal of Hexavalent chromium (Cr (VI)) from synthetically prepared wastewater. The synthesized particles were characterized using scanning electron microscopy equipped with energy dispersive X-Ray spectroscopy, X ray diffraction and thermogravimetric analyzer. Batch adsorption studies were conducted to study the effects of pH, magnetite dosage, time and initial concentration on Cr (VI) removal. Adsorption isotherm study was also conducted. Optimum pH for the present work was 3.0 and all the other studies were done at this pH. The adsorption followed Freundlich isotherm model.UV-VIS spectrophotometer was used to measure the concentration of Hexavalent chromium in water.

Abstract We propose in this White Paper a concept for a space experiment using cold atoms to search for ultra-light dark matter, and to detect gravitational waves in the frequency range between the most sensitive ranges of LISA and the terrestrial LIGO/Virgo/KAGRA/INDIGO experiments. This interdisciplinary experiment, called Atomic Experiment for Dark Matter and Gravity Exploration (AEDGE), will also complement other planned searches for dark matter, and exploit synergies with other gravitational wave detectors. We give examples of the extended range of sensitivity to ultra-light dark matter offered by AEDGE, and how its gravitational-wave measurements could explore the assembly of super-massive black holes, first-order phase transitions in the early universe and cosmic strings. AEDGE will be based upon technologies now being developed for terrestrial experiments using cold atoms, and will benefit from the space experience obtained with, e.g., LISA and cold atom experiments in microgravity. KCL-PH-TH/2019-65, CERN-TH-2019-126

Plasma generated by fundamental radiation from a Nd:YAG laser focused onto a graphite target is studied spectroscopically. Measured line profiles of several ionic species were used to infer electron temperature and density at several sections located in front of the target surface. Line intensities of successive ionization states of carbon were used for electron temperature calculations. Stark broadened profiles of singly ionized species have been utilized for electron density measurements. Electron density as well as electron temperature were studied as functions of laser irradiance and time elapsed after the incidence of laser pulse. The validity of the assumption of local thermodynamic equilibrium is discussed in light of the results obtained.

The NOvA experiment has seen a $4.4\ensuremath{\sigma}$ signal of ${\overline{\ensuremath{\nu}}}_{e}$ appearance in a 2 GeV ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ beam at a distance of 810 km. Using $12.33\ifmmode\times\else\texttimes\fi{}{10}^{20}$ protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{\nu}}}_{e}$ candidates with a background of 10.3 and 102 ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ candidates. This new antineutrino data are combined with neutrino data to measure the parameters $|\mathrm{\ensuremath{\Delta}}{m}_{32}^{2}|=2.4{8}_{\ensuremath{-}0.06}^{+0.11}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{ }{\mathrm{eV}}^{2}/{c}^{4}$ and ${\mathrm{sin}}^{2}{\ensuremath{\theta}}_{23}$ in the ranges from (0.53--0.60) and (0.45--0.48) in the normal neutrino mass hierarchy. The data exclude most values near ${\ensuremath{\delta}}_{CP}=\ensuremath{\pi}/2$ for the inverted mass hierarchy by more than $3\ensuremath{\sigma}$ and favor the normal neutrino mass hierarchy by $1.9\ensuremath{\sigma}$ and ${\ensuremath{\theta}}_{23}$ values in the upper octant by $1.6\ensuremath{\sigma}$.

The Russian and Norwegian Arctic are gaining notoriety as an alternative maritime route connecting the Atlantic and Pacific Oceans and as sources of natural resources. The renewed interest in the Northeast Passage or the Northern Sea Route is fueled by a recession of Arctic sea ice coupled with the discovery of new natural resources at a time when emerging and global markets are in growing demand for them. Driven by the expectation of potential future economic importance of the region, political interest and governance has been rapidly developing, mostly within the Arctic Council. However, this paper argues that optimism regarding the potential of Arctic routes as an alternative to the Suez Canal is overstated. The route involves many challenges: jurisdictional disputes create political uncertainties; shallow waters limit ship size; lack of modern deepwater ports and search and rescue (SAR) capabilities requires ships to have higher standards of autonomy and safety; harsh weather conditions and free-floating ice make navigation more difficult and schedules more variable; and more expensive ship construction and operation costs lessen the economic viability of the route. Technological advances and infrastructure investments may ameliorate navigational challenges, enabling increased shipping of natural resources from the Arctic to global markets.

The strong cross-equatorial low level jet stream (LLJ) with its core around 850 hPa of the Asian summer monsoon (June–September) is found to have large intraseasonal variability. During the monsoon onset over Kerala, India, and during break monsoon periods, when the convective heating of the atmosphere is over the low latitudes of the Indian Ocean, the axis of the LLJ is oriented southeastward over the eastern Arabian Sea and it flows east between Sri Lanka and the equator and there is no LLJ through peninsular India. This affects the transport of moisture produced over the Indian Ocean to peninsular India and the Bay of Bengal. In contrast, during active monsoon periods when there is an east–west band of strong convective heating in the latitudes 10°–20°N from about longitude 70° to about 120°E, the LLJ axis passes from the central Arabian Sea eastward through peninsular India and it provides moisture for the increased convection in the Bay of Bengal and for the monsoon depressions forming there. The LLJ does not show splitting into two branches over the Arabian Sea. Splitting of the jet was first suggested by Findlater and has since found wide acceptance as seen from the literature. Findlater's findings were based on analysis of monthly mean winds. Such an analysis is likely to show the LLJ of active and break monsoons as occurring simultaneously, suggesting a split. Strengths of the convective heat source (OLR) over the Bay of Bengal and the strength of the LLJ (zonal component of wind) at 850 hPa over peninsular India and also the Bay of Bengal between latitudes 10° and 20°N have the highest linear correlation coefficient at a lag of 2–3 days, with OLR leading. The LLJ crossing the equator close to the coast of East Africa will pass through India only if there is active monsoon convection in the latitude belt 10°–20°N over south Asia. The position in latitude of the LLJ axis between longitudes 70° and 100°E is decided by the south–north movement of the east–west convective cloud band of the monsoon in its 30–50-day oscillation. When there is little convection over south Asia in the latitude belt 10°–20°N, the LLJ crossing the equator curves clockwise over the Arabian Sea under conservation of potential vorticity and bypassing India passes east close to the equator. It is speculated that the cyclonic vorticity associated with this low-latitude LLJ causes convergence in the boundary layer and consequent upward motion in the atmosphere resulting in the formation of a convective cloud band there that later moves into the Bay of Bengal as part of the monsoon's 30–50-day oscillation. Since LLJ is very important in monsoon dynamics, monsoon modelers should take adequate care to see that LLJ and the associated deep convection and their intraseasonal variability are properly simulated in their models.

Nanostructured photocatalysts have always offered opportunities to solve issues concerned with the environmental challenges caused by rapid urbanization and industrialization. These materials, due to their tunable physicochemical characteristics, are capable of providing a clean and sustainable ecosystem to humanity. One of the current thriving research focuses of visible-light-driven photocatalysts is on the nanocomposites of titanium dioxide (TiO2) with carbon nanostructures, especially graphene. Coupling TiO2 with graphene has proven more active by photocatalysis than TiO2 alone. It is generally considered that graphene sheets act as an electron acceptor facilitating the transfer and separation of photogenerated electrons during TiO2 excitation, thereby reducing electron-hole recombination. This study briefly reviews the fundamental mechanism and interfacial charge-transfer dynamics in TiO2/graphene nanocomposites. Design strategies of various graphene-based hybrids are highlighted along with some specialized synthetic routes adopted to attain preferred properties. Importantly, the enhancing interfacial charge transfer of photogenerated e¯CB through the graphene layers by morphology orientation of TiO2, predominated exposure of their high energy crystal facets, defect engineering, enhancing catalytic sites in graphene, constructing dedicated architectures, tuning the nanomaterial dimensionality at the interface, and employing the synergism adopted through various modifications, are systematically compiled. Portraying the significance of these photocatalytic hybrids in environmental remediation, important applications including air and water purification, self-cleaning surfaces, H2 production, and CO2 reduction to desired fuels, are addressed.

We present results from sun/sky radiometer measurements of aerosol optical characteristics carried out in New Delhi during March–June, 2006, as part of the Indian Space Research Organization's Integrated Campaign for Aerosol Radiation Budget. For the first time at this site, derived are parameters such as aerosol optical depth (AOD), single scattering albedo (SSA), asymmetry parameter, Ångstrom exponent, and real and imaginary refractive indices in five spectral channels. During the campaign, a consistent increase in aerosol loading from March to June with monthly average AOD values at 0.5 μ m of 0.55, 0.75, 1.22 and 1.18, respectively, was observed. Ångstrom exponent gradually decreases from 1.28 (March) to 0.47 (June), indicating an increased abundance of coarse particles due to dust storms that transport desert dust from the Thar desert and adjoining regions. SSA at 0.5 μ m is found to be in the range of 0.84 to 0.74 from March to June, indicating an increasing contribution from the mixture of anthropogenic and desert dust absorbing aerosols. Optical properties derived during the campaign are used in a radiative‐transfer model to estimate aerosol radiative forcing at the surface and at the top‐of‐the atmosphere. A consistent increase in surface cooling is evident, ranging from −39 W m −2 (March) to −99 W m −2 (June) and an increase in heating of the atmosphere from 27 W m −2 (March) to 123 W m −2 (June). Heating rates in the lower atmosphere (up to 5 km) are 0.6, 1.3, 2.1, and 2.5K/d from March, April, May, and June 2006, respectively. Higher aerosol induced heating in the premonsoon period has been shown to have an impact on the regional monsoon climate.

Antimicrobial resistance (AMR) is a major threat to global health. Understanding the emergence, evolution, and transmission of individual antibiotic resistance genes (ARGs) is essential to develop sustainable strategies combatting this threat. Here, we use metagenomic sequencing to analyse ARGs in 757 sewage samples from 243 cities in 101 countries, collected from 2016 to 2019. We find regional patterns in resistomes, and these differ between subsets corresponding to drug classes and are partly driven by taxonomic variation. The genetic environments of 49 common ARGs are highly diverse, with most common ARGs carried by multiple distinct genomic contexts globally and sometimes on plasmids. Analysis of flanking sequence revealed ARG-specific patterns of dispersal limitation and global transmission. Our data furthermore suggest certain geographies are more prone to transmission events and should receive additional attention.

Stable, OH free zinc oxide (ZnO) nanoparticles were synthesized by hydrothermal method by varying the growth temperature and concentration of the precursors. The formation of ZnO nanoparticles were confirmed by x-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) studies. The average particle size have been found to be about 7-24 nm and the compositional analysis is done with inductively coupled plasma atomic emission spectroscopy (ICP-AES). Diffuse reflectance spectroscopy (DRS) results shows that the band gap of ZnO nanoparticles is blue shifted with decrease in particle size. Photoluminescence properties of ZnO nanoparticles at room temperature were studied and the green photoluminescent emission from ZnO nanoparticles can originate from the oxygen vacancy or ZnO interstitial related defects.

Purpose The study attempts to chart out the role of switching costs in the interrelationships between perceived value, perceived service quality, customer satisfaction, and customer retention. The mediating role of switching costs as well as its direct impact is explored among customers of mobile telephone service providers in India. Design/methodology/approach The conceptual model is developed based on the existing literature and then the model is validated through the analysis of data collected from customers of mobile services in India. Findings The mediating role of switching costs is found to have adequate statistical support and the other direct linkages are also found to be valid. The findings suggest that service firms may benefit from pursuing a combined strategy of increasing customer satisfaction and switching costs both independently and in tandem, depending upon the product‐market characteristics. Originality/value The study extends the knowledge about customer retention by bringing in switching costs as a part of the network of relationship involving perceived value, perceived service quality, and customer satisfaction.

We report results from the first search for ν_{μ}→ν_{e} transitions by the NOvA experiment. In an exposure equivalent to 2.74×10^{20} protons on target in the upgraded NuMI beam at Fermilab, we observe 6 events in the Far Detector, compared to a background expectation of 0.99±0.11(syst) events based on the Near Detector measurement. A secondary analysis observes 11 events with a background of 1.07±0.14(syst). The 3.3σ excess of events observed in the primary analysis disfavors 0.1π<δ_{CP}<0.5π in the inverted mass hierarchy at the 90% C.L.

An integrated hydrogeological investigation has been made to delineate the groundwater‐potential zones of the Muvattupuzha river basin, Kerala, along the southwest coast of India. The basin is characterized by charnockites and gneisses of Archean age covering more than 80% of the area and the remaining by Pleistocene laterites and Miocene formation. The basin receives high rainfall, measuring 3100 mm/year. However, acute water shortage occurs during the premonsoon season and hence, a number of dug wells are made to tap the groundwater. Seasonal rainfall during NE and SW monsoons is the major source of groundwater recharge. Further, hydrogeomorphology, geology, fracture systems and the slope of the terrain also play a significant role on the movement and behaviour of the groundwater of this basin. The integration of conventional and remote sensing data has been made through geographic information system (GIS) and it is found that about 50% of the area can be identified as very good or good potential zones, whereas the remaining area falls under moderate and poor categories. Most of the Muvattupuzha sub‐basin and the western part of the Kothamangalam and Kaliyar sub‐basins are classified as good groundwater‐potential zones, although the eastern upstream part of the basin has poor groundwater potential.

The creation of three-dimensionally engineered nanoporous architectures via covalently interconnected nanoscale building blocks remains one of the fundamental challenges in nanotechnology. Here we report the synthesis of ordered, stacked macroscopic three-dimensional (3D) solid scaffolds of graphene oxide (GO) fabricated via chemical cross-linking of two-dimensional GO building blocks. The resulting 3D GO network solids form highly porous interconnected structures, and the controlled reduction of these structures leads to formation of 3D conductive graphene scaffolds. These 3D architectures show promise for potential applications such as gas storage; CO2 gas adsorption measurements carried out under ambient conditions show high sorption capacity, demonstrating the possibility of creating new functional carbon solids starting with two-dimensional carbon layers.