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We consider the simultaneous propagation of two contagions over a social network. We assume a threshold model for the propagation of the two contagions and use the formal framework of discrete dynamical systems. In particular, we study an optimization problem where the goal is to minimize the total number of new infections subject to a budget constraint on the total number of available vaccinations for the contagions. While this problem has been considered in the literature for a single contagion, our work considers the simultaneous propagation of two contagions. This optimization problem is NP-hard. We present two main solution approaches for the problem, namely an integer linear programming (ILP) formulation to obtain optimal solutions and a heuristic based on a generalization of the set cover problem. We carry out a comprehensive experimental evaluation of our solution approaches using many real-world networks. The experimental results show that our heuristic algorithm produces solutions that are close to the optimal solution and runs several orders of magnitude faster than the ILP-based approach for obtaining optimal solutions. We also carry out sensitivity studies of our heuristic algorithm.
Functional movement disorders (FMDs) pose significant diagnostic and management challenges. We aimed to study the socioeconomic and cultural factors, underlying psychopathology and the phenomenology of FMDs in children.
The study is a retrospective chart review of 39 children (16 girls and 23 boys) who attended our neurology OPD and the movement disorders clinic at the National Institute of Mental Health and Neurosciences (NIMHANS) between January 2011 and May 2020. The diagnosis of FMD was based on Fahn and Williams criteria and the patients were either diagnosed as “documented” or “clinically established”. All the relevant demographic data including the ethnicity, socioeconomic and cultural background, examination findings, electrophysiological, and other investigations were retrieved from the medical records.
The mean age at onset was 12.69 ± 3.13 years. Majority of the children were from urban regions (56.41%) and belonging to low socioeconomic status (46.15%). Thirty (76.92%) were found to have a precipitating factor. Myoclonus was the most common phenomenology observed in these patients (30.76%), followed by tremor (20.51%), dystonia (17.94%), and gait abnormality (7.69%). Chorea (5.12%) and tics (2.56%) were uncommon. Tremor (37.5%) and dystonia (18.75%) were more common in girls, whereas myoclonus (39.13%) was more common in boys.
The symptoms of FMD have great impact on the mental health, social, and academic functioning of children. It is important to identify the precipitating factors and associated psychiatric comorbidities in these children as prompt alleviation of these factors by engaging parents and the child psychiatrist will yield better outcomes.
The radiocarbon (14C) calibration curve so far contains annually resolved data only for a short period of time. With accelerator mass spectrometry (AMS) matching the precision of decay counting, it is now possible to efficiently produce large datasets of annual resolution for calibration purposes using small amounts of wood. The radiocarbon intercomparison on single-year tree-ring samples presented here is the first to investigate specifically possible offsets between AMS laboratories at high precision. The results show that AMS laboratories are capable of measuring samples of Holocene age with an accuracy and precision that is comparable or even goes beyond what is possible with decay counting, even though they require a thousand times less wood. It also shows that not all AMS laboratories always produce results that are consistent with their stated uncertainties. The long-term benefits of studies of this kind are more accurate radiocarbon measurements with, in the future, better quantified uncertainties.
Two different processing routes of mechanical alloying followed by the spark plasma sintering (powder metallurgy) and vacuum arc melting (casting route) were employed to understand the role of processing routes on the phase and microstructural evolution in an equiatomic CrMoNbTiW refractory high-entropy alloy. Besides a major BCC solid solution, a small fraction of carbide, σ phase, nitride, and oxide phases were observed in the alloys prepared by the powder metallurgy route in contrast to a single-phase BCC solid solution in the casting route. The milling atmosphere (dry milling in air and Ar) has significantly influenced the phase and microstructural evolution, illustrating the substantial role of contaminants. Good thermal stability of microstructure at high homologous temperatures was shown based on the long-term heat treatment at 1300 °C for 240 h. The phase evolution predictions via Calphad studies were found to be in reasonable agreement with the experimental observations, albeit with some limitations.
The DSM-IV criteria recognize the existence of obsessive–compulsive disorder (OCD) with poor insight. However, there is paucity of literature on the clinical correlates and treatment response in poor and good insight OCD. In this study, insight is measured by using the Brown Assessment of Beliefs Scale (BABS) developed specifically to assess insight. One hundred subjects with DSM-IV OCD were ascertained from the OCD clinic of a large psychiatric hospital in India. All subjects were evaluated extensively by using structured instruments and established measures of psychopathology. The subjects were treated with adequate doses of drugs for adequate period. The results showed that 25% of the subjects had poor insight. Poor insight was associated with earlier age-at-onset, longer duration of illness, more number of obsessive–compulsive symptoms, more severe illness and higher comorbidity rate, particularly major depression. Of the subjects who were treated adequately (N = 73), 44 (60%) were treatment responders. Poor insight was associated with poor response to drug treatment. In the step-wise logistic regression analysis, baseline BABS score was highly predictive of poor treatment response. Poor insight appears to be associated with specific clinical correlates and poor response to drug treatment. Further studies are needed in larger samples to replicate our findings.
Novel commercially available software has enabled registration of both CT and MRI images to rapidly fuse with X-ray fluoroscopic imaging. We describe our initial experience performing cardiac catheterisations with the guidance of 3D imaging overlay using the VesselNavigator system (Philips Healthcare, Best, NL). A total of 33 patients with CHD were included in our study. Demographic, advanced imaging, and catheterisation data were collected between 1 December, 2016 and 31 January, 2019. We report successful use of this technology in both diagnostic and interventional cases such as placing stents and percutaneous valves, performing angioplasties, occlusion of collaterals, and guidance for lymphatic interventions. In addition, radiation exposure was markedly decreased when comparing our 10–15-year-old coarctation of the aorta stent angioplasty cohort to cases without the use of overlay technology and the most recently published national radiation dose benchmarks. No complications were encountered due to the application of overlay technology. 3D CT or MRI overlay for CHD intervention with rapid registration is feasible and aids decisions regarding access and planned angiographic angles. Operators found intraprocedural overlay fusion registration using placed vessel guidewires to be more accurate than attempts using bony structures.
It is known that 12C beam transmission through the accelerator decreases at high beam currents. This effect depends on machine design and varies across different types of AMS instruments. For beam currents of about 100 μA, the effect is small on the 500 kV tandem CAMS unit, whereas beam saturation is observed for similar high beam currents on the 250 kV SSAMS unit. While this effect is very evident for high 12C beam currents, we have also observed that even the 13C beam is found to suffer modest transmission loss with beam current. As a result, the 13C/12C ratio does not remain constant with beam current. By correcting for the effects of 12C beam saturation and decreased 13C transmission, we have obtained online δ13C values that are more accurate and precise at moderately high beam currents for SSAMS.
The Molonglo Observatory Synthesis Telescope (MOST) is an 18000 m2 radio telescope located 40 km from Canberra, Australia. Its operating band (820–851 MHz) is partly allocated to telecommunications, making radio astronomy challenging. We describe how the deployment of new digital receivers, Field Programmable Gate Array-based filterbanks, and server-class computers equipped with 43 Graphics Processing Units, has transformed the telescope into a versatile new instrument (UTMOST) for studying the radio sky on millisecond timescales. UTMOST has 10 times the bandwidth and double the field of view compared to the MOST, and voltage record and playback capability has facilitated rapid implementaton of many new observing modes, most of which operate commensally. UTMOST can simultaneously excise interference, make maps, coherently dedisperse pulsars, and perform real-time searches of coherent fan-beams for dispersed single pulses. UTMOST operates as a robotic facility, deciding how to efficiently target pulsars and how long to stay on source via real-time pulsar folding, while searching for single pulse events. Regular timing of over 300 pulsars has yielded seven pulsar glitches and three Fast Radio Bursts during commissioning. UTMOST demonstrates that if sufficient signal processing is applied to voltage streams, innovative science remains possible even in hostile radio frequency environments.
The class of radio transients called Fast Radio Bursts (FRBs) encompasses enigmatic single pulses, each unique in its own way, hindering a consensus for their origin. The key to demystifying FRBs lies in discovering many of them in order to identity commonalities – and in real time, in order to find potential counterparts at other wavelengths. The recently upgraded UTMOST in Australia, is undergoing a backend transformation to rise as a fast transient detection machine. The first interferometric detections of FRBs with UTMOST, place their origin beyond the near-field region of the telescope thus ruling out local sources of interference as a possible origin. We have localised these bursts to much better than the ones discovered at the Parkes radio telescope and have plans to upgrade UTMOST to be capable of much better localisation still.
We computationally investigate coupling of a nonlinear rotational dissipative element to a sprung circular cylinder allowed to undergo transverse vortex-induced vibration (VIV) in an incompressible flow. The dissipative element is a ‘nonlinear energy sink’ (NES), consisting of a mass rotating at fixed radius about the cylinder axis and a linear viscous damper that dissipates energy from the motion of the rotating mass. We consider the Reynolds number range $20\leqslant Re\leqslant 120$, with $Re$ based on cylinder diameter and free-stream velocity, and the cylinder restricted to rectilinear motion transverse to the mean flow. Interaction of this NES with the flow is mediated by the cylinder, whose rectilinear motion is mechanically linked to rotational motion of the NES mass through nonlinear inertial coupling. The rotational NES provides significant ‘passive’ suppression of VIV. Beyond suppression however, the rotational NES gives rise to a range of qualitatively new behaviours not found in transverse VIV of a sprung cylinder without an NES, or one with a ‘rectilinear NES’, considered previously. Specifically, the NES can either stabilize or destabilize the steady, symmetric, motionless-cylinder solution and can induce conditions under which suppression of VIV (and concomitant reduction in lift and drag) is accompanied by a greatly elongated region of attached vorticity in the wake, as well as conditions in which the cylinder motion and flow are temporally chaotic at relatively low $Re$.
Safflower is a traditional oilseed crop in the world. Its seed oil is a healthy edible oil containing high amount of unsaturated fatty acids. Genetically diverse exotic cultivars are valuable germplasm for introducing new diversity in safflower improvement programmes. In this study, we characterized safflower cultivars of India (30) and Mexico (23) comprising varieties, hybrids and advanced lines developed over 50 years for genetic distinctiveness using 38 simple sequence repeat (SSR) loci. Genetic diversity estimates across cultivar groups (total, India and Mexico) were as follows: mean number of alleles (3.2, 3.1, 2.6), expected heterozygosity (0.42, 0.37, 0.37) and polymorphism information content (0.36, 0.33, 0.32) respectively, which suggested narrow SSR allelic diversity within and between cultivar groups. However, distance-based cluster analysis (neighbour-joining tree) and model-based STRUCTURE analysis revealed that safflower cultivars of India and Mexico, with the exception of a few, form two genetically distinct groups. High level of genetic variation explained between the populations (40%) and Fst estimate (0.4) suggested that the cultivar groups were highly differentiated with limited gene flow supporting a strong genetic structuring. High oil (~38%) and high oleic (73–79%) contents of a subset of Mexican safflower varieties and advanced lines were confirmed in field trials in India. These exotic sources from Mexico are valuable for safflower breeding programmes in India to develop new cultivars with high oil yielding potential and high oleic acid content, which is the current market demand.
Crystalline silicon based photovoltaics continues to be the dominant technology for large scale deployment of solar energy. While impressive cost gains in silicon based PV have come with scale, there remains a strong push for increased efficiencies and further lowering of manufacturing costs to achieve true grid parity. So far, however, there has not been a production proven approach that reduces the cost while maintaining or increasing the efficiency. Attempts to reduce the amount of silicon used, for example, have led to development of various kerfless wafer manufacturing approaches. While some of these approaches have shown the potential for reduced costs, they also compromise the efficiency mainly due to the inferior quality of the material.
Epitaxy based kerfless silicon wafers, on the other hand, has shown the potential to reverse this trend offering lower manufacturing costs while maintaining or even enhancing the efficiency due to the high quality of the n-type and p-type silicon epitaxial (Epi) wafers. In this work, we present key aspects of Crystal Solar’s patented high throughput production silicon epitaxial reactor and its use in the manufacture of standard thickness N and P wafers. Besides the advantage of having significantly reduced cost, these Epi wafers have high quality, better mechanical strength and resistance to light inducted degradation due to significantly reduced oxygen content.
A ‘pulsar timing array’ (PTA), in which observations of a large sample of pulsars spread across the celestial sphere are combined, allows investigation of ‘global’ phenomena such as a background of gravitational waves or instabilities in atomic timescales that produce correlated timing residuals in the pulsars of the array. The Parkes Pulsar Timing Array (PPTA) is an implementation of the PTA concept based on observations with the Parkes 64-m radio telescope. A sample of 20 ms pulsars is being observed at three radio-frequency bands, 50 cm (~700 MHz), 20 cm (~1400 MHz), and 10 cm (~3100 MHz), with observations at intervals of two to three weeks. Regular observations commenced in early 2005. This paper describes the systems used for the PPTA observations and data processing, including calibration and timing analysis. The strategy behind the choice of pulsars, observing parameters, and analysis methods is discussed. Results are presented for PPTA data in the three bands taken between 2005 March and 2011 March. For 10 of the 20 pulsars, rms timing residuals are less than 1 μs for the best band after fitting for pulse frequency and its first time derivative. Significant ‘red’ timing noise is detected in about half of the sample. We discuss the implications of these results on future projects including the International Pulsar Timing Array and a PTA based on the Square Kilometre Array. We also present an ‘extended PPTA’ data set that combines PPTA data with earlier Parkes timing data for these pulsars.
A new 250kV single stage AMS accelerator (SSAMS) was installed at the Center for Applied Isotope Studies, University of Georgia. The accelerator is intended to be used primarily for radiocarbon measurements of natural and biobased samples, while all other samples such as marine, geological, atmospheric and archaeological samples are measured on the decade-old 500kV compact tandem accelerator (CAMS). The new AMS system is equipped with a 134-cathode MC-SNICS ion source. In this article, we show the results of the tests carried out on standards and blanks and compare the performance of the new machine with that of the CAMS unit. We have also compared the stable isotope data from AMS measurements to the conventional isotope ratio mass spectrometers (IRMS) data.
A low thermal budget process for back-end compatible PCMO based RRAM cell is essential for 3D stacked memory. In this paper, we investigate two strategies to engineer low thermal budget processing for bipolar switching - (i) deposition engineering i.e. based on deposition temperature and oxygen partial pressure, (ii) post deposition anneal i.e. based on inert anneal of room temperature deposited PCMO film.. We demonstrate that both deposition and anneal shows a transition temperature above which bipolar switching is realized. Oxygen partial pressure is a key deposition process parameter. As oxygen partial pressure is reduced memory window increases, however beyond an optimal O2 partial pressure, unipolar switching is observed. Inert anneal is more effective in thermal budget reduction as N2/550°C/2min anneal has same memory performance as 650°C/2hour deposition process.
Radiocarbon and stable isotope determination in foods, flavors, and beverages, for the authentication of source material and process of formation, is a well-established method of identity used in industry. New methods of provenance determination, using stable isotopes of oxygen and hydrogen, have added to the host of other isotopic methods used for characterizing natural or botanically derived products. The unambiguous determinant of a product's fossil fuel origin be it from petroleum, natural gas, or coal, is through the measurement of its 14C content. The 14C content can also be used to determine the fraction dilution of recently grown and harvested material with that derived from fossil fuel, and even confirms the vintage of agricultural products based on the well-established decrease of bomb-produced atmospheric 14C. This paper documents 14C measurements at the University of Georgia's Center for Applied Isotope Studies accelerator mass spectrometry and stable isotope laboratories, over the last 3 yr, for 10 important flavoring compounds. By establishing an accurate and current level of 14C in botanically derived products, we were able to confirm a particular source for vanilla production, the most popular consumer flavor in the marketplace. Over the years, vanilla extract has been produced less and less from vanilla beans (Vanilla planifolia), particularly those from Madagascar and the Comoros Islands, and more from other botanical precursors such as ferulic acid, clove oil, and guaiacol. We report isotopic data to support this precursor for vanilla production based on high 14C levels accumulated during the tree's life, incorporated in the tree rings and their associated stable isotope abundances.
In this paper we advocate the study of discrete models of social dynamics under adversarial scheduling. The approach we propose forms part of a foundational basis for a generative approach to social science (Epstein 2007). We highlight the feasibility of the adversarial scheduling approach by using it to study the Prisoners's Dilemma Game with Pavlov update, a dynamics that has already been investigated under random update in Kittock (1994), Dyer et al. (2002), Mossel and Roch (2006) and Dyer and Velumailum (2011). The model is specified by letting players at the nodes of an underlying graph G repeatedly play the Prisoner's Dilemma against their neighbours. The players adapt their strategies based on the past behaviour of their opponents by applying the so-called win–stay lose–shift strategy. With random scheduling, starting from any initial configuration, the system reaches the fixed point in which all players cooperate with high probability. On the other hand, under adversarial scheduling the following results hold:
— A scheduler that can select both game participants can preclude the system from reaching the unique fixed point on most graph topologies.
— A non-adaptive scheduler that is only allowed to choose one of the participants is no more powerful than a random scheduler. With this restriction, even an adaptive scheduler is not significantly more powerful than the random scheduler, provided it is ‘reasonably fair’.
The treatment of disorders of the nervous system poses a major clinical challenge. Development of neuromodulation (i.e., interfacing electronics to nervous tissue to modulate its function) has provided patients with neuronal-related deficits a new tool to regain lost function. Even though, in principle, electrical stimulation and recording by interfacing technology is simple and straightforward, each presents different challenges. In stimulation, the challenge lies in targeting the effects of stimulation on precise brain regions, as each region specializes for particular functions on a millimeter scale. In practice, our experience with deep brain stimulation for treating Parkinson’s disease reveals that stimulation of larger regions of the brain can be relatively well tolerated. However, the task of fabricating an ideal electrode that performs reliably for long periods of time has been daunting. The primary obstacle in successful interfacing comes from integration of electrodes (“foreign” material) into the nervous system (biological material). The second tier of complexity is added by the need for the electrodes to “sense” signals emanating from individual neurons, an estimated microenvironment of 10 to 20 microns in diameter. Materials design and technology impact electrode design—with their size, shape, mechanical properties, and composition all being actively optimized to enable chronic, stable recordings of neural activity. The articles in this issue discuss designing interfacing technology to “listen to the nervous system” from a materials perspective. These include identification of materials with a potential for in vivo development, electrodes with various material types, including natural nanocomposites, and optical neural interfacing.
This paper presents an experimental investigation on the role of return current in excitation of electronmagnetohydrodynamic (EMHD) structures. It is shown that only when return currents are excited parallel or anti-parallel to the background magnetic field the EMHD structures can be excited by a biased electrode in the plasma.