A 12.4-day periodicity in a close binary system after a supernova.

Neutron stars and stellar-mass black holes are the remnants of massive star explosions1. Most massive stars reside in close binary systems2, and the interplay between the companion star and the newly formed compact object has been theoretically explored3, but signatures for binarity or evidence for the formation of a compact object during a supernova explosion are still lacking. Here we report a stripped-envelope supernova, SN 2022jli, which shows 12.4-day periodic undulations during the declining light curve. Narrow Hα emission is detected in late-time spectra with concordant periodic velocity shifts, probably arising from hydrogen gas stripped from a companion and accreted onto the compact remnant. A new Fermi-LAT γ-ray source is temporally and positionally consistent with SN 2022jli. The observed properties of SN 2022jli, including periodic undulations in the optical light curve, coherent Hα emission shifting and evidence for association with a γ-ray source, point to the explosion of a massive star in a binary system leaving behind a bound compact remnant. Mass accretion from the companion star onto the compact object powers the light curve of the supernova and generates the γ-ray emission.

Microscopic Cracks Modulate Nucleation and Solid-State Crystallization Tendency of Amorphous Celecoxib.

Drugs have been classified as fast, moderate, and poor crystallizers based on their inherent solid-state crystallization tendency. Differential scanning calorimetry-based heat-cool-heat protocol serves as a valuable tool to define the solid-state crystallization tendency. This classification helps in the development of strategies for stabilizing amorphous drugs. However, microscopic characteristics of the samples were generally overlooked during these experiments. In the present study, we evaluated the influence of microscopic cracks on the crystallization tendency of a poorly water-soluble model drug, celecoxib. Cracks developed in the temperature range of 0-10 °C during the cooling cycle triggered the subsequent crystallization of the amorphous phase. Nanoindentation study suggested minimal differences in mechanical properties between samples, although the cracked sample showed relatively inhomogeneous mechanical properties. Nuclei nourishment experiments suggested crack-assisted nucleation, which was supported by Raman data that revealed subtle changes in intermolecular interactions between cracked and uncracked samples. Celecoxib has been generally classified as class II, i.e., a drug with moderate crystallization tendency. Interestingly, classification of amorphous celecoxib may change depending on the presence or absence of cracks in the amorphous sample. Hence, subtle events such as microscopic cracks should be given due consideration while defining the solid-state crystallization tendency of drugs.

Minutes-duration optical flares with supernova luminosities.

In recent years, certain luminous extragalactic optical transients have been observed to last only a few days1. Their short observed duration implies a different powering mechanism from the most common luminous extragalactic transients (supernovae), whose timescale is weeks2. Some short-duration transients, most notably AT2018cow (ref. 3), show blue optical colours and bright radio and X-ray emission4. Several AT2018cow-like transients have shown hints of a long-lived embedded energy source5, such as X-ray variability6,7, prolonged ultraviolet emission8, a tentative X-ray quasiperiodic oscillation9,10 and large energies coupled to fast (but subrelativistic) radio-emitting ejecta11,12. Here we report observations of minutes-duration optical flares in the aftermath of an AT2018cow-like transient, AT2022tsd (the 'Tasmanian Devil'). The flares occur over a period of months, are highly energetic and are probably nonthermal, implying that they arise from a near-relativistic outflow or jet. Our observations confirm that, in some AT2018cow-like transients, the embedded energy source is a compact object, either a magnetar or an accreting black hole.

Facile and Green Synthesis of Novel Fluorescent Carbon Quantum Dots and Their Silver Heterostructure: An In Vitro Anticancer Activity and Imaging on Colorectal Carcinoma.

Carbon dots (CQDs) have been widely investigated as prime candidates for developing a tumor theranostic platform due to their tunable fluorescence emission and excitation, high water solubility, good photostability, and biocompatibility. Among the CQDs, natural CQDs are an emerging class of nanomaterials in the carbon family. Herein, highly fluorescent carbon quantum dots (CQDs) were synthesized from orange juice using a one-step hydrothermal method and characterized by different techniques. After that, CQD/Ag heterostructures were synthesized by the reduction of silver salt, in particular silver nitrate (AgNO3) solution using sodium borohydride (NaBH4) in different ratios. The photostability and characterization of CQD/Ag heterostructures were investigated. At last, a comparative cellular toxicity measurement was done to select the superior CQD/Ag heterostructure in the human colorectal carcinoma (HCT 116) cell line along with the imaging property. The detailed cell death signaling was also observed in the HCT 116 cell line via the ROS-dependent mitochondrial-mediated pathway, where Akt (RAC-α serine/threonine-protein kinase) played a important role.

A very luminous jet from the disruption of a star by a massive black hole.

Tidal disruption events (TDEs) are bursts of electromagnetic energy that are released when supermassive black holes at the centres of galaxies violently disrupt a star that passes too close1. TDEs provide a window through which to study accretion onto supermassive black holes; in some rare cases, this accretion leads to launching of a relativistic jet2-9, but the necessary conditions are not fully understood. The best-studied jetted TDE so far is Swift J1644+57, which was discovered in γ-rays, but was too obscured by dust to be seen at optical wavelengths. Here we report the optical detection of AT2022cmc, a rapidly fading source at cosmological distance (redshift z = 1.19325) the unique light curve of which transitioned into a luminous plateau within days. Observations of a bright counterpart at other wavelengths, including X-ray, submillimetre and radio, supports the interpretation of AT2022cmc as a jetted TDE containing a synchrotron 'afterglow', probably launched by a supermassive black hole with spin greater than approximately 0.3. Using four years of Zwicky Transient Facility10 survey data, we calculate a rate of [Formula: see text] per gigapascals cubed per year for on-axis jetted TDEs on the basis of the luminous, fast-fading red component, thus providing a measurement complementary to the rates derived from X-ray and radio observations11. Correcting for the beaming angle effects, this rate confirms that approximately 1 per cent of TDEs have relativistic jets. Optical surveys can use AT2022cmc as a prototype to unveil a population of jetted TDEs.

First report of gut bacterial dataset of a tribal Bhutia family from West Bengal, India.

The tribes of West Bengal are distributed in geographically distinct regions with distinctive features of their habitats and many of these tribes still practice a traditional livelihood avoiding the western diet. Hence, it is expected that their gut should remain pristine. In this study, we report the gut bacterial abundance of a Drukpa Bhutia tribal family of Lepchakha, inhabiting the hilly terrain of the Buxa region of Alipurduar district. First fecal matter was collected followed by Illumina Hiseq sequencing. Following standard protocols for metagenomic analysis, quality control (FASTQC), taxonomic profiling (QIIME, KRONA) and pathogenic load analysis were performed. This study revealed a set of core gut bacteria among which Bacteroides was identified to be the most abundant followed by Bifidobacterium, Streptococcus etc. Genera exhibiting lowest abundance were Eggerthella, Ruminococcus, Enterococcus etc. among the male, kid and female respectively. This data provides important insights into the distribution of bacterial members under study.

Dietary Intake and Nutritional Status of the adult Kheria Sabar males of West Bengal, India.

Kheria Sabars are an indigenous community living in the rural areas of Purulia, West Bengal, India. This work aims to study dietary intake and its relation to nutritional status among adult Kheria Sabar males aged 18-60. The study entails the recording of anthropometric variables like height (cm) and weight (kg) as per the standard protocol and calculating body mass index (BMI). Dietary intake was recorded on the basis of the 24-h dietary recall method. The intake of different nutrients was computed and compared with the Recommended Dietary Allowances (RDA) for Indians by the Indian Council of Medical Research Expert Committee. Results revealed a paradox where undernutrition was prevalent (44.28%) despite balanced nutrient intake. This paradox creates scope for further exploratory research among other communities living in similar habitats.

Learning versus habit formation: Optimal timing of lockdown for disease containment.

We analyze a model where the government has to decide whether to impose a lockdown in a country to prevent the spread of a possibly virulent disease. If the government decides to impose a lockdown, it has to determine its intensity, timing and duration. We find that there are two competing effects that push the decision in opposite directions. An early lockdown is beneficial not only to slow down the spread of the disease, but creates beneficial habit formation (such as social distancing, developing hygienic habits) that persists even after the lockdown is lifted. Against this benefit of an early lockdown, there is a cost from loss of information about the virulence and spread of the disease in the population in addition to a direct cost to the economy. Based on the prior probability of the disease being virulent, we characterize the timing, intensity and duration of a lockdown with the above mentioned tradeoffs. Specifically, we show that as the precision of learning goes up, a government tends to delay the imposition of lockdown. Conversely, if the habit formation parameter is very strong, a government is likely to impose an early lockdown.

Strategic experimentation with asymmetric players.

We examine a two-player game with two-armed exponential bandits à la (Keller et al. in Econometrica 73:39-68, 2005), where players operate different technologies for exploring the risky option. We characterise the set of Markov perfect equilibria and show that there always exists an equilibrium in which the player with the inferior technology uses a cut-off strategy. All Markov perfect equilibria imply the same amount of experimentation but differ with respect to the expected speed of the resolution of uncertainty. If and only if the degree of asymmetry between the players is high enough, there exists a Markov perfect equilibrium in which both players use cut-off strategies. Whenever this equilibrium exists, it welfare dominates all other equilibria. This contrasts with the case of symmetric players, where there never exists a Markov perfect equilibrium in cut-off strategies.

Gut microbial dataset of a foraging tribe from rural West Bengal - insights into unadulterated and transitional microbial abundance.

The human gut microbiome contributes to a broad range of biochemical and metabolic functions that directly or indirectly affect human system. Numerous factors such as age, geographical location, genetic makeup, and individual health status significantly influence the diversity, stability, and relative abundance of the gut microbiome. Of the mentioned factors, geographical location and dietary practices appears to explain a significant portion of microbiome variation. On the other hand tribal people living in geographically isolated areas and dependent on their traditional food sources are considered as having relatively unadulterated gut as their guts are least colonized by Western diet. The Western diet - low in fiber and high in refined sugars - is basically wiping out species of bacteria from our intestines. That's the conclusion Smits (2017) and his team reached after analyzing the Hadza microbiome at one stage of their year long study. The trend was clear: The further away people's diets are from a Western diet, the greater the variety of microbes they tend to have in their guts. And that includes bacteria that are missing from American guts."So whether it's people in Africa, Papua New Guinea or South America, communities that live a traditional lifestyle have common gut microbes - ones that we all lack in the industrialized world. In this work we present a pilot study data of the gut microbiome of an ethnic tribe of West Bengal, India, originating from Dravidian descent - the Savars. These are nomadic tribes and are still dependent on hunting and gathering for their livelihood. We identified a healthy family and have analysed their stool samples for gut microbial profiles.