Atmospheric aerosol chemistry and source apportionment of PM10 using stable carbon isotopes and PMF modelling during fireworks over Hyderabad, southern India.

This study examined the influence of fireworks on atmospheric aerosols over the Southern Indian city of Hyderabad during festival of Diwali using mass closure, stable carbon isotopes and the EPA-PMF model. Identification of chemical species in day and night time aerosol samples for 2019 and 2020 Diwali weeks showed increased concentrations of NH4+, NO3-, SO42-, K+, organic carbon (OC), Ba, Pb and Li, which were considered as tracers for fireworks. PM10 source apportionment was done using inorganic (trace elements, major ions) and carbonaceous (organic and elemental carbon; OC & EC) constituents, along with stable isotopic compositions of TC and EC. K+/Na+ ∼1 and K+nss/OC > 0.5 indicated contribution from fireworks. High NO3-, NH4+, Na+, Cl- and SO42- suggested the presence of deliquescent salts NaCl, NH4NO3 and (NH4)2SO4. TAE/TCE >1 suggested H+ exclusion, indicating possible presence of H2SO4 and NH4HSO4 in the aerosols. Ba, Pb, Sb, Sr and Fe increased by 305 (87), 12 (11), 12 (3), 3 (2) and 3 (4) times on Diwali nights, compared to pre-Diwali of 2019 (2020), and are considered as metallic tracers of fireworks. δ13CTC and δ13CEC in aerosols closely resembled that of diesel and C3 plant burning emissions, with meagre contribution from firecrackers during Diwali period. The δ13CEC was relatively depleted than δ13CTC and δ13COC. For both years, δ13COC-EC (δ13COC - δ13CEC) were positive, suggesting photochemical aging of aerosols during long-range transport, while for pre-Diwali 2019 and post-Diwali 2020, δ13COC-EC were negative with high OC/EC ratio, implying secondary organic aerosols formation. High toluene during Diwali week contributed to fresh SOA formation, which reacted with precursor 12C, leading to 13C depletions. Eight-factored EPA-PMF source apportionment indicated highest contribution from residue/waste burning, followed by marine/dust soil and fireworks, while least was contributed from solid fuel/coal combustion.

Topological Exact Flat Bands in Two-Dimensional Materials under Periodic Strain.

We study flat bands and their topology in 2D materials with quadratic band crossing points under periodic strain. In contrast to Dirac points in graphene, where strain acts as a vector potential, strain for quadratic band crossing points serves as a director potential with angular momentum ℓ=2. We prove that when the strengths of the strain fields hit certain "magic" values, exact flat bands with C=±1 emerge at charge neutrality point in the chiral limit, in strong analogy to magic angle twisted-bilayer graphene. These flat bands have ideal quantum geometry for the realization of fractional Chern insulators, and they are always fragile topological. The number of flat bands can be doubled for certain point group, and the interacting Hamiltonian is exactly solvable at integer fillings. We further demonstrate the stability of these flat bands against deviations from the chiral limit, and discuss possible realization in 2D materials.

Dynamics of Self-Dual Kagome Metamaterials and the Emergence of Fragile Topology.

Recent years have seen the discovery of systems featuring fragile topological states. These states of matter lack certain protection attributes typically associated with topology and are therefore characterized by weaker signatures that make them elusive to observe. Moreover, they are typically confined to special symmetry classes and, in general, rarely studied in the context of phononic media. In this Letter, we theoretically predict the emergence of fragile topological bands in the spectrum of a twisted kagome elastic lattice with threefold rotational symmetry, in the so-called self-dual configuration. A necessary requirement is that the lattice is a structural metamaterial, in which the role of the hinges is played by elastic finite-thickness ligaments. The interplay between the edge modes appearing in the band gaps bounding the fragile topological states is also responsible for the emergence of corner modes at selected corners of a finite hexagonal domain, which qualifies the lattice as a second-order topological insulator. We demonstrate our findings through a series of experiments via 3D scanning laser doppler vibrometry conducted on a physical prototype. The selected configuration stands out for its remarkable geometric simplicity and ease of physical implementation in the panorama of dynamical systems exhibiting fragile topology.

Synthetically non-Hermitian nonlinear wave-like behavior in a topological mechanical metamaterial.

Topological mechanical metamaterials have enabled new ways to control stress and deformation propagation. Exemplified by Maxwell lattices, they have been studied extensively using a linearized formalism. Herein, we study a two-dimensional topological Maxwell lattice by exploring its large deformation quasi-static response using geometric numerical simulations and experiments. We observe spatial nonlinear wave-like phenomena such as harmonic generation, localized domain switching, amplification-enhanced frequency conversion, and solitary waves. We further map our linearized, homogenized system to a non-Hermitian, nonreciprocal, one-dimensional wave equation, revealing an equivalence between the deformation fields of two-dimensional topological Maxwell lattices and nonlinear dynamical phenomena in one-dimensional active systems. Our study opens a regime for topological mechanical metamaterials and expands their application potential in areas including adaptive and smart materials and mechanical logic, wherein concepts from nonlinear dynamics may be used to create intricate, tailored spatial deformation and stress fields greatly transcending conventional elasticity.

Relapse during opioid use disorder treatment: A pilot study to understand the reasons for opioid use during treatment.

Background: Opioid use is a cause of concern in many parts of the world. About 2.1% Indians use opioids. Opioids are also the most common drugs used by injection drug users in India. Despite various treatment strategies used to manage opioid use disorders (OUDs), relapse is common. A good treatment program would make efforts to address lapses and prevent relapse. Hence, there is a need to understand the factors associated with relapse in OUD. Method: One hundred and twenty patients completed a baseline assessment that included socio-demographic details and the Maudsley Addiction Profile (MAP). They were followed up for three months and assessed using telephonic interview for opioid use. All those who relapsed were assessed using the Reasons for Relapse Questionnaire (RRQ). The patients who relapsed were compared with the patients who were abstinent. Relapse was defined as any use of opioid during follow-up. Results: Forty participants relapsed during the 90 days of the study period. Relapsed patients had a greater number of conflict days with family members, used a higher amount of heroin and cannabis at baseline, were less likely to be discharged on buprenorphine, and were more likely to drop out. Participants cited mood and social reasons more often than cue/craving and unwell domains of RRQ. Conclusion: Baseline treatment and prospective factors are associated with relapse in OUD. Addressing these factors can help in reducing relapse in OUD patients.

Acceptability, usability and efficacy of an automatic respiratory monitor in determining fast breathing: A pilot study in a tribal tea garden in India.

Background: Childhood pneumonia is one of the leading causes of mortality among under-five children. It is responsible for 15% of all deaths of children U5, killing 808,694 children in 2017 (1). Traditional visual inspection and manual count method is used to detect and classify fast-breathing, a key indicator of Pneumonia. In response to UNICEF's call for a reliable diagnostic tool, Philips was the first to respond with the Children's Automatic Respiratory Monitor for measuring fast breathing objectively. Aim: UNICEF and Philips Foundation initiated a field study to test the acceptability, usability and efficacy of the Automatic Respiratory Monitor in Determining Fast Breathing in low resource setting environments. Settings and Design: Philips Foundation partnered up with the Directorate of Medical Education in West Bengal, India to conduct the field study amongst community healthcare workers and beneficiaries in a rural district of West Bengal. In collaboration with North Bengal Medical College & Hospital, a community-based study was conducted in a tribal tea garden of Naxalbari block. Methods and Material: Acceptability and usability of the device was assessed through structtured interviews and dialogues with community health workers (CHWs), caregivers and local healthcare practitioners. Efficacy of the device was represented by the inter-rater agreement between the traditional visual inspection and manual count method and the device reading. Statistical Analysis Used: A descriptive community based mixed method study was conducted. Satisfaction among community healthcare workers (CHWs) and beneficiaries was found to be promising across all study parameters. Results and Conclusions: The paper captures the study methods, statistical analysis of the data, the conclusions, areas of further research and recommends community-wide use of the device in objectively measuring fast breathing among children under the age of five years.

Method of image charges for describing deformation of bounded two-dimensional solids with circular inclusions.

We present a method for predicting the linear response deformation of finite and semi-infinite 2D solid structures with circular holes and inclusions by employing the analogies with image charges and induction in electrostatics. Charges in electrostatics induce image charges near conductive boundaries and an external electric field induces polarization (dipoles, quadrupoles, and other multipoles) of conductive and dielectric objects. Similarly, charges in elasticity induce image charges near boundaries and external stress induces polarization (quadrupoles and other multipoles) inside holes and inclusions. Stresses generated by these induced elastic multipoles as well as stresses generated by their images near boundaries then lead to interactions between holes and inclusions and with their images, which induce additional polarization and thus additional deformation of holes and inclusions. We present a method that expands induced polarization in a series of elastic multipoles, which systematically takes into account the interactions of inclusions and holes with the external field, between them, and with their images. The results of our method for linear deformation of circular holes and inclusions near straight and curved boundaries show good agreement with both linear finite element simulations and experiments.

Elastic multipole method for describing deformation of infinite two-dimensional solids with circular inclusions.

Elastic materials with holes and inclusions are important in a large variety of contexts ranging from construction material to biological membranes. More recently, they have also been exploited in mechanical metamaterials, where the geometry of highly deformable structures is responsible for their unusual properties, such as negative Poisson's ratio, mechanical cloaking, and tunable phononic band gaps. Understanding how such structures deform in response to applied external loads is thus crucial for designing novel mechanical metamaterials. Here we present a method for predicting the linear response of infinite 2D solid structures with circular holes and inclusions by employing analogies with electrostatics. Just like an external electric field induces polarization (dipoles, quadrupoles, and other multipoles) of conductive and dielectric objects, external stress induces elastic multipoles inside holes and inclusions. Stresses generated by these induced elastic multipoles then lead to interactions between holes and inclusions, which induce additional polarization and thus additional deformation of holes and inclusions. We present a method that expands the induced polarization in a series of elastic multipoles, which systematically takes into account the interactions of inclusions and holes with the external stress field and also between them. The results of our method show good agreement with both linear finite element simulations and experiments.

Brainstem hypoxic-ischemic lesions on MRI in infants treated with therapeutic cooling: effects on the length of stay and mortality.

OBJECTIVE: To test the hypothesis that brainstem hypoxic-ischemic injury on magnetic resonance imaging (MRI) would be independently associated with short-term outcomes in cooled asphyxiated infants. METHODS: A total of 90 consecutively cooled asphyxiated infants who survived to have brain MRI were reviewed. A neuroradiologist who was masked to outcomes evaluated MRI images for brainstem involvement. Outcomes were mortality and length of stay. RESULTS: Brainstem lesions were present on post-cooling brain MRI in 20 of the 90 infants (22%). Overall, four infants died before discharge, and all four had brainstem involvement. The infants with brainstem involvement had longer hospital stay (29 days, IQR 20-47 versus 16 days, IQR 10-26; P = 0.0001), compared to infants without brainstem lesions (n = 70); and upon multivariate analysis, brainstem involvement remained independently associated with prolonged hospital stay (ß = 12.4, P = 0.001). CONCLUSION: This study demonstrates the importance of recognizing brainstem injury for the prediction of short-term outcomes in cooled asphyxiated infants.

Does maternal intrapartum antibiotic treatment prolong the incubation time required for blood cultures to become positive for infants with early-onset sepsis?

BACKGROUND: We hypothesized that maternal intrapartum antibiotic treatment delays the growth of the organism in the blood culture obtained during the work-up for infants with suspected early-onset sepsis (EOS). METHODS: Single center, retrospective review of infants with blood culture-proven EOS over 13.5 years period. EOS was defined by isolation of a pathogen from blood culture obtained within 72 hours of birth and antibiotic treatment for ≥ 5 days. RESULTS: Among 81 infants with positive blood cultures, 38 were deemed to have EOS and 43 were deemed contaminants. The organisms grown were as follows: Escherichia coli in 17 infants, Group B streptococcus in 10 infants, and others in 11 infants. Overall, 17 infants with EOS did not receive intrapartum antibiotics and had blood cultures drawn for being symptomatic after birth. The other 21 infants who received intrapartum antibiotics had blood culture drawn primarily for maternal chorioamnionitis. The median (interquartile range [IQR]) incubation time to blood culture positivity was not different in infants who received intrapartum antibiotics compared with infants who did not (19.6 hours, IQR 16-28 hours vs. 19.5 hours, IQR 17.2-21.6 hours, p = 0.7489). CONCLUSION: Maternal intrapartum antibiotic treatment did not delay the time to blood culture positivity in infants with EOS.