Bifurcation cascade, self-similarity, and duality in the three-rotor problem.

The three-rotor system concerns equally massive point particles moving on a circle subject to attractive cosine potentials of strength g. The quantum theory models chains of coupled Josephson junctions. Classically, it displays order-chaos-order behavior with increasing energy E along with a seemingly globally chaotic phase for 5.33g≲E≲5.6g. It is also known to admit pendulum and isosceles breather families of periodic orbits at all energies. While pendula display a doubly infinite sequence of stability transitions accumulating at their libration to rotation threshold at E=4g, breathers undergo only one stability transition. Here, we show that these stability transitions are associated with forward and reverse fork-like isochronous and period-doubling bifurcations. The new family of periodic orbits born at each of these bifurcations is found using an efficient search algorithm starting from a transverse perturbation to the parent orbit. The graphs of stability indices of various classes of orbits born at pendulum bifurcations meet at E=4g forming "fans." The transitions in the librational and rotational phases are related by an asymptotic duality between bifurcation energies and shapes of newly born periodic orbits. The latter are captured by solutions to a Lamé equation. We also find and numerically validate values of scaling constants for self-similarity in (a) stability indices of librational and rotational pendula and (b) shapes of newly born orbits as E→4g. Finally, we argue that none of the infinitely many families of periodic orbits we have found is stable for 5.33g≲E≲5.6g, providing further evidence for global chaos in this energy band.

Impact of Top Electrodes (Cu, Ag, and Al) on Resistive Switching behaviour of Cu-rich Cu2 ZnSnS4 (CZTS) Ideal Kesterite.

Cu2 ZnSnS4 (CZTS) active material-based resistive random-access memory (RRAM) devices are investigated to understand the impact of three different Cu, Ag, and Al top electrodes. The dual resistance switching (RS) behaviour of spin coated CZTS on ITO/Glass is investigated up to 102 cycles. The stability of all the devices (Cu/CZTS/ITO, Ag/CZTS/ITO, and Al/CZTS/ITO) is investigated up to 103  sec in low- (LRS) and high- (HRS) resistance states at 0.2 V read voltage. The endurance up to 102 cycles with 30 msec switching width shows stable write and erase current. Weibull cumulative distribution plots suggest that Ag top electrode is relatively more stable for set and reset state with 33.61 and 25.02 shape factors, respectively. The charge carrier transportation is explained by double logarithmic plots, Schottky emission plots, and band diagrams, substantiating that at lower applied electric field intrinsic copper ions dominate in Cu/CZTS/ITO, whereas, at higher electric filed, top electrodes (Cu and Ag) dominate over intrinsic copper ions. Intrinsic Cu+ in CZTS plays a decisive role in resistive switching with Al electrode. Further, the impedance spectroscopy measurements suggest that Cu+ and Ag+ diffusion is the main source for the resistive switching with Cu and Ag electrodes.

Changing sleep patterns and anxiety due to Covid-19 home confinement among working population: A cross-sectional study.

Introduction: The COVID-19 pandemic took the entire world unawares and people were forced to stay indoors overnight. Due to this a drastic change ensued in lifestyle with many succumbing to various kinds of stresses and psychological problems. This study aims to study the changing sleep patterns and level of anxiety among the working population due to the COVID-19 Pandemic lockdown. Methodology: An online survey was conducted using a cloud-based website. The sleep patterns both prior to and during the lockdown period of the pandemic were assessed using a self-administered questionnaire. The level of anxiety during both these periods (before and during lockdown) amongst the working population was also assessed using the Generalized Anxiety Disorder Scores (GADS). Results: A total of 224 individuals participated in the study of which 52.7% were males and 47.3% were females. On analysis, the lifestyle and sleep deprivation scores showed that before the lockdown only 2.7% reported a low score out of total participants. However, this number was raised to 13.4% during the lockdown. The percentage of people reporting deteriorated sleep quality gradually increased with females reporting moderate to severe category of Generalized Anxiety Disorder scores as compared to Males. Conclusion: The study suggests that there has been a significant change in the sleep quality of the study participants due to Covid enforced lockdown which if unnoticed might lead to significant health problems. The effective use of programs like yoga, meditation, and deep breathing exercises, if followed timely could reduce psychological distress to some extent.

Low power highly flexible BiFeO3-based resistive random access memory (RRAM) with the coexistence of negative differential resistance (NDR).

We demonstrated the resistive random access memory characteristics for Cu (top contact)/BFO/PMMA (active layer)/ITO (bottom electrode)/PET sheet as a flexible substrate device configuration. The device showed non-volatile bipolar resistive switching characteristics with good repeatability and the coexistence of NDR for 100 cycles or more with 0.28/3.43 mW power consumption for 1st/100th cycles. The device retains its read state for 104 s or more and switches from LRS to HRS or vice versa for 103 cycles with a pulse width of 100 ms for a write-read-erase-read pulse without affecting the memory characteristics. The Weibull distribution suggests that a set state is more stable than the reset state with shape factor ß = 25.20. The device follows Ohmic behavior for the lower applied external field and Child square and Schottky emission for the higher external fields. The Joule heating, Sorets, and Fick's forces are responsible for the formation and rupturing of ionic filament. The coexistence of resistive switching and flexible strength of the device sustains the bending curvature of infinity, 0.2 cm, 1 cm, 1.7 cm, and 2.2 cm. The memory characteristics are retained under tensile conditions for 100 cycles or more. More interestingly, the power consumption for sustaining the NDR region with bending (19 µW) is much lower than without bending (0.19 mW). Thus, this study provides the possibility of integrating BFO with flexible substrates suitable for hybrid organic/inorganic memory structures.

Central-to-Axial Chirality: Asymmetric Organocatalytic Synthesis of Axially Chiral Chalcones via Exocyclic Dihydronaphthalenes.

Asymmetric synthesis of an unprecedented exocyclic dihydronaphthalene and an axially chiral naphthalene chalcone has been disclosed. Good to excellent asymmetric induction is achieved. The success is attributed to the unusual formation of exocyclic dihydronaphthalene, which plays a crucial role in ensuring axial chirality. This is the first report of exocyclic molecules capable of enabling the synthesis of axially chiral chalcones via stepwise asymmetric vinylogous domino double-isomerization using secondary amine catalysis.

A comparative assessment of subjective experience in simulator and on-road driving under normal and time pressure driving conditions.

This study conducts a comparative assessment of subjective experience of real-world and simulated world driving for investigating factors leading to simulator sickness. Thirty professional car drivers drove a fixed-base driving simulator in real and simulated worlds under No Time Pressure (NTP) and Time Pressure (TP) driving conditions. Drivers rated their perceptions based on real-world driving and simulator driving experiences after each driving session with respect to three factors: simulator sickness, mental workload, and sense of presence. The structural equation model results revealed that drivers experienced high mental workload due to TP driving conditions (factor loading = 0.90) and repeated exposure to simulated world (factor loading = 0.20) which induced simulator sickness (factor loading = 0.41) and resulted in low sense of presence (factor loading = -0.18). Thus, it can be concluded that lack of experience with virtual reality induced high simulator sickness, increased mental workload, and low sense of presence.

Clustering pedestrians' perceptions towards road infrastructure and traffic characteristics.

In India, over 25,000 pedestrian fatalities occur due to road crashes every year. While several studies have identified possible causative factors that contribute to these fatalities, little is known about how pedestrians perceive their surrounding environment. This study attempts to bridge this gap by analysing the pedestrian perception of the built environment and traffic-related aspects considering urban roads (arterial and sub-arterial). Fourteen parameters were selected to assess pedestrian perception, and four factors were derived through factor analysis. The obtained factor scores were then subjected to two-step cluster analysis to determine whether pedestrian perception is different for people from different socio-economic demographics with varying travel behaviour. Based on the results obtained from the descriptive analysis, the respondents were most satisfied with the 'quality of streetlights at sidewalks' and 'visibility/sight distances', while they were most dissatisfied with 'pedestrian volume at sidewalks' and 'lighting facilities at crossings'. From the cluster analysis, it can be summarized that female pedestrians walk less frequently than males and perceive a higher probability of collision or near-collision incidents against male pedestrians. The study findings can aid the policymakers in the assessment of the pedestrian perception of the existing road infrastructure and suggest improvements to ensure pedestrian safety.

Investigating the role of beliefs in influencing the hand-held and hands-free mobile phone use among pedestrians in India.

Mobile phone distraction is a significant contributor to pedestrian injuries. However, mobile phone engagement among pedestrians has been scarcely explored in a developing country like India. The present study utilized the beliefs-based theory of planned behaviour to examine the association between pedestrian beliefs towards distracted walking (behavioural, normative, and control) and their mobile phone use frequencies. Based on a survey of 560 pedestrians (64.6% males), it was found that the major use of mobile phones was for listening to music (30.7%), followed by receiving a call (25%), making a call (18.9%), texting (9.8%), navigation (8.5%) and internet browsing (7.1%). A series of multivariate ANOVAs and logistic regression models were developed to investigate the relationships between the beliefs and frequencies of mobile phone use in hands-free and hand-held conditions. Significant multivariate differences were found for behavioural and normative beliefs in hands-free conditions and all three types of beliefs in hand-held conditions. The frequency of mobile phone use was significantly predicted by normative beliefs (p < 0.001) in the hands-free condition, and by behavioural (p = 0.041) and normative beliefs (p = 0.004) in the hand-held condition. The findings may assist the road safety countermeasures in addressing the issue of pedestrian distraction.

Sustainable and Chemoselective Synthesis of α-Aminonitriles Using Lewis and Brønsted Acid-Functionalized Nanoconfined Spaces.

α-Aminonitriles are significant components in the synthesis of biological compounds and complex drugs. Although efficient, procedures for synthesizing α-aminonitriles suffer from high loadings of expensive catalysts, long reaction times, energy-intensive conditions, and expensive, toxic solvents. Herein, we report the use of metal-organic framework Cr-MIL-101-SO3H as a catalyst for the facile synthesis of eight α-aminonitriles, five of which are reported as new molecules. We found that the presence of both open Cr3+ Lewis and -SO3H Brønsted acids in the MIL-101 pores is vital for the one-pot synthesis of α-aminonitriles. The catalytic reaction is conducted under solvent-free conditions at room temperature and a Cr-MIL-101-SO3H loading of 1% by the total mass, which is considered a sustainable synthetic pathway of α-aminonitriles. Additionally, we demonstrated for the first time that Cr-MIL-101-SO3H exhibits a high degree of catalytic chemoselectivity, differing substrates with sterically hindered and electronically withdrawn functional groups. Our study expands the existing family of α-aminonitriles and provides an intelligent strategy for the development of catalysts that can be used to synthesize functional α-aminonitriles with potential in therapeutics and health applications.

Microbial electrosynthesis from carbon dioxide feedstock linked to yeast growth for the production of high-value isoprenoids.

The difficulty in producing multi-carbon and thus high-value chemicals from CO2 is one of the key challenges of microbial electrosynthesis (MES) and other CO2 utilization technologies. Here, we demonstrate a two-stage bioproduction approach to produce terpenoids (>C20) and yeast biomass from CO2 by linking MES and yeast cultivation approaches. In the first stage, CO2 (C1) is converted to acetate (C2) using Clostridium ljungdahlii via MES. The acetate is then directly used as the feedstock to produce sclareol (C20), ß-carotene (C40), and yeast biomass using Saccharomyces cerevisiae in the second stage. With the unpurified acetate-containing (1.5 g/L) spent medium from MES reactors, S. cerevisiae produced 0.32 ± 0.04 mg/L ß-carotene, 2.54 ± 0.91 mg/L sclareol, and 369.66 ± 41.67 mg/L biomass. The primary economic analysis suggests that sclareol and biomass production is feasible using recombinant S. cerevisiae and non-recombinant S. cerevisiae, respectively, directly from unpurified acetate-containing spent medium of MES.

Modelling the pedestrian dilemma zone at uncontrolled midblock sections.

INTRODUCTION: Pedestrians at high-speed midblock crossings with the intention to cross the road usually face safety risks due to difficulty in judging the available gaps. The risk to pedestrians is high in developing nations like India since priorities are not respected by road users. Moreover, the non-yielding vehicular traffic puts pedestrians at further risk. While crossing the road, pedestrians are clear about rejecting small gaps and accepting the large gaps, however, they experience a dilemma between the small and large gaps. METHOD: This study attempts to model the dilemma zone for pedestrians intending to cross the high-speed roads (posted speed limit of 60 km/h). The field data were collected using high-definition video cameras at two uncontrolled midblock crossings, each in the cities of Mumbai and Kolhapur, located in the southwestern part of India. The variations in the spatial gap acceptance behavior were analyzed for 1,107 pedestrian observations using binary logit models. RESULTS: The findings revealed that the length and the distribution of the dilemma zone were significantly affected by the speed of the approaching vehicle and the distance from it. Moreover, the influence of vehicle type (truck, car, or two-wheeler), pedestrian type (walking alone or in a group), crossing speed, and waiting time also influenced pedestrians' gap acceptance behavior. Interestingly, pedestrians' gender did not play a significant role in their road crossing decisions. CONCLUSIONS: Overall, the study identified the dilemma zone boundaries that will help pedestrians to judge the safe gaps while crossing, and in turn, reduce the probability of pedestrian-vehicle crashes. Practical Application: The proposed dilemma zone intends to protect the pedestrians by assisting in making precise crossing decisions at high-speed midblock crossings.

Males of the parasitoid wasp, Nasonia vitripennis, can identify which fly hosts contain females.

The reproductive success of a male is limited by the number of females it can mate with. Thus, males deploy elaborate strategies to maximize access to females. In Nasonia, which are parasitoids of cyclorrhaphous flies, such reproductive strategies are thought to be restricted to competition among males for access to females in the natal patch. This study investigates whether additional strategies are present, especially the capability to identify which fly hosts contain adult females inside. Behavioural assays revealed that only one out of the four species, N. vitripennis, can distinguish which hosts specifically have adult female wasps, indicating a species-specific reproductive strategy. Results of gas chromatography-mass spectrometry analyses and behavioural data suggest that female-signature cuticular hydrocarbons (CHCs) are used as chemical cues, possibly emanating from within the host puparium. Further assays indicated that N. vitripennis males can also detect differences in the intensities of female-signature CHCs, giving them the capability to seek out hosts with maximum number of females. This study uncovers a previously unknown reproductive strategy in one of the most widely studied parasitoid wasps.

Interaction of Active Janus Colloids with Tracers.

Understanding the motion of artificial active swimmers in complex surroundings, such as a dense bath of passive particulate matter, is essential for their successful utilization as cargo (drug) carriers and sensors or for medical imaging, under microscopic domains. In this study, we experimentally investigated the motion of active SiO2-Pt Janus particles (JPs) in a two-dimensional bath of smaller silica tracers dispersed with varying areal densities. Our observations indicate that when an active JP undergoes a collision with an isolated tracer, their interaction can have a significant impact on the swimmer's motion. However, the overall impact of tracers on the active JPs' motion (translation and rotation) depends on the frequency of collisions and also on the nature of the collision, which is marked by the time-duration for which the particles maintain contact during the collisions. Further, in the high-density tracer bath, our experiments reveal that the motion of the active JP results in a novel organizational behavior of the tracers on the trailing Pt (depletion of tracers) and the leading SiO2 (accumulation of tracers) side. In laboratory frame the emergence and the subsequent vanishing of the depletion zone are discussed in detail.

Exploring supercapacitance of solvothermally synthesized N-rGO sheet: role of N-doping and the insight mechanism.

We demonstrate the method of achieving excellent supercapacitance in nitrogen-doped reduced graphene oxide (N-rGO) sheets by controlling the amount of N-content through the use of different ratios of GO and urea during solvothermal synthesis. Here, urea plays a dual role in reducing GO and simultaneously doping nitrogen into the GO flakes forming exfoliated N-rGO sheets. The nitrogen content in N-rGO samples rises with an increase in the amounts of urea and saturates at a value of ∼14% for the GO : urea ratios beyond 1 : 8. The obtained N-rGO sheets with ∼ 5% N-content (obtained for GO : urea ratio of 1 : 3) were demonstrated as excellent supercapacitor materials. Using a 3-electrode setup, the maximum specific capacitance obtained for this sample was 514 F g-1 at a current density of 0.5 A g-1 (mass normalized current). The insights into the origin of this excellent supercapacitive behavior are explained through our results on optimum N-content, the relative amount of different N-environments, defects/disorders, and the degree of reduction of GO. Importantly, a proper stacking of rGO sheets with moderate N-content (∼5-6%) and a moderate amount of defects is the key to achieve high specific-capacitance. Furthermore, our 2-electrode device demonstrates the excellence of our samples with a Csp of 237 F g-1, a power density of 225 W kg-1, and an energy density of 6.7 W h kg-1 at 0.5 A g-1, exhibiting a high cyclic constancy with high capacitive retention of ∼ 82% even after 8000 cycles. Hence, our work provides a way to control the properties of N-rGO in achieving excellent supercapacitive performance.

Effect of lithium salt on fluorescence quenching in glycerol: a comparison with ionic liquid/deep eutectic solvent.

It was reported earlier that the addition of LiCl to the deep eutectic solvent (DES) ChCl:Urea (composed of the salt choline chloride and the H-bond donor urea in 1 : 2 molar ratio) and the addition of LiTf2N [Tf2N:(CF3SO2)2N] to the ionic liquid (IL) [C2C1im][Tf2N] ([C2C1im]:1-ethyl-3-methylimidazolium), respectively, results in an increase in the dynamic viscosity of the medium. However, as the concentration of the Li salt is increased, instead of decreasing, the bimolecular quenching rate constant (kq) for the quenching of pyrene fluorescence by nitromethane is observed to first increase and only then decreases within both media. This unusual initial increase in quenching is hypothesized to be due to structural changes in the DES ChCl:Urea and the IL [C2C1im][Tf2N], respectively, as the Li salt is added. We tested this hypothesis by comparing the physical properties and fluorescence quenching behavior between 1 wt% water in glycerol solution which has similar viscosity to that of the DES ChCl:Urea with the aforementioned DES and IL in the presence of lithium salt as media. In complete contrast, irrespective of the temperature, kq is found to decrease monotonically with increasing concentration of LiCl within 1 wt% water in glycerol media. These findings therefore highlight the unusual characteristics of ILs and DESs as solubilizing media. The ionic nature of the IL and the high concentration of ions in the DES are deemed responsible for these outcomes.

Modelling work- and non-work-based trip patterns during transition to lockdown period of COVID-19 pandemic in India.

COVID-19 pandemic has significantly affected the transportation sector across the world. Implementation of lockdown (that includes restricted travel activities) is a prevention strategy executed by various governments to minimize the spread of COVID-19. India went into complete lockdown from 25th March 2020; however, change in commuter's travel behavior was observed from the third week of March (termed as transition to lockdown) due to pandemic fear. In total 1945 participants participated in the travel behaviour survey and their responses with respect to work-based and non-work-based trips during transition period were analysed to understand their adaptation towards COVID-19. The study also attempted to quantify the effects of influencing factors which can explain change in the commuters' travel behaviour. The findings revealed that one-year increment in traveller's age had 2% reduced probability of no travel during transition than pre-transition. For non-work-related travel, chances of lower travel frequency were significantly greater during the transition period as compared to pre-transition. Compared to the non-essential trips, the chances of reduced travel frequency for the essential trips were found to be lower by 92%. By examining these behavioural changes, the present study aims to assist the policymakers in understanding the dynamics of fluctuating travel demand with respect to trip purpose during pandemic situations like COVID-19.

Are you willing to drink and drive? An investigation in Indian scenario using an extended prototype willingness model.

OBJECTIVE: Driving While Intoxicated (DWI) is a significant threat to traffic safety worldwide, but little is known about the motivational factors behind the willingness to drink and drive especially in low- and middle-income countries (LMICs) such as India. The present study applied an extended version of prototype willingness model (PWM) to investigate the factors predicting the willingness to drink and drive. METHODS: One hundred and forty-three participants (77% males) responded to an online survey in India. The survey included the standard PWM constructs such as attitudes, subjective norms, prototype similarity and prototype favourability. Additionally, the measures of traffic fatalism and risk-perceptions were also incorporated to examine their effects on the willingness to drink and drive. RESULTS: The hierarchical regression model showed that the PWM constructs explained 84% of the variance in willingness to drink and drive. When the additional measures (traffic fatalism and risk perception) were included along with the PWM variables, it resulted in an increase of additional 2% of the variance in explaining the willingness, thereby leading to a total of 86%. In both the steps, the variable "attitudes" was found to be the strongest predictor of willingness to drink and drive. CONCLUSIONS: This study is first of its kind to evaluate the effectiveness of PWM model in Indian scenario for understanding the willingness to engage in the act of drunk driving. The study findings may prove useful to the stakeholders of educational and awareness programs, where the focus is required to be aimed at attitudes, subjective norms, prototype similarity and fatalistic beliefs of the drivers.

Modelling brake transition time of young alcohol-impaired drivers using hazard-based duration models.

Braking performance of drivers is a crucial factor in evaluating the collision patterns and implementing road safety measures. Further, alcohol is known to impair driving control. The present study aims to examine the influence of a comprehensive range of Blood Alcohol Concentration (BAC) levels (0%, 0.03 %, 0.05 % and 0.08 %) on brake transition times of drivers. As young drivers show significantly higher crash risks compared to the experienced drivers, fifty-four young Indian drivers in the age group of 21-25 years (forty males and fourteen females) participated in the driving simulator experiments. The study adopted the framework of a within-subjects design, where each driver encountered rural and urban driving scenarios in a counterbalanced order, during experimental driving at each of the four BAC levels. Their brake transition times were estimated with respect to sudden pedestrian crossing events. Weibull Accelerated Failure Time (AFT) models with shared frailty were developed for quantifying the effects of BAC levels along with driver attributes on brake transition time. Preliminary analysis showed significant main effects of BAC (p < 0.001) and driving environment (p = 0.002) on brake transition time; however, their interaction effect was not significant (p = 0.485). The models revealed that 0.03 %, 0.05 % and 0.08 % BACs significantly reduced the brake transition times by 16 %, 28 % and 52 % in rural driving environment, and by 23 %, 37 % and 53 % in urban driving environment, compared to 0% BAC. The study outcomes may find application in assisting collision warning systems which take into account the braking behaviour of drivers.

Modeling the influence of 0.03%, 0.05% and 0.08% blood alcohol concentrations on lane positioning and steering control of Indian drivers.

OBJECTIVE: Alcohol-impairment of drivers has significant influence on road traffic safety; however, no experimental research has been conducted on the lateral driving control of Indian drivers. Therefore, the present study investigates the effects of different Blood Alcohol Concentration (BAC) levels (0%, 0.03%, 0.05% and 0.08%) and driver attributes on the lane positioning and steering control of Indian drivers. METHOD: A driving simulator experiment was designed where 82 adult licensed drivers (62 males, 20 females) completed driving on the simulated urban arterial road environment under the influence of varying BACs. Lateral driving performance measures associated with lane positioning (lane position variability) and steering control of drivers (steering angle variability and steering reversal rates (SRR)) were analyzed. RESULTS: The findings reported that lane position variability was significantly influenced only at 0.08% BAC (5.8% increment); no significant influence was observed at 0.03% and 0.05% BACs. Compared to 0% BAC, steering angle variability increased by 0.105 degrees or 15.7%, 0.142 degrees or 21.4%, and 0.176 degrees or 25.7% at 0.03%, 0.05% and 0.08% BACs respectively. No significant differences were observed between the sober-state driving and alcohol-impaired driving at 1ο and 5ο SRR. However, 10ο SRR was found to be higher by 36%, 65% and 92% at 0.03%, 0.05% and 0.08% BACs compared to 0% BAC. Among the driver attributes, male drivers displayed higher impairment in lane positioning behavior as compared to female drivers. One-year increase in drivers' age reduced the lane position variability by 0.6%. Drivers who performed regular physical exercise were found to have better lateral control on the vehicle, as observed in their steering angle variability. Prior crash history had negative association with the steering reversal rates, indicating that drivers who have previous experience of crash involvement show better steering control than the drivers without any crash experience. CONCLUSION: In conclusion, the outcomes of this study provide novel insights into the alcohol-impaired lateral vehicle control of Indian drivers which can assist in policy interventions aiming to reduce crashes with alcohol as a major crash causation factor.