We present a search for extragalactic fast blue optical transients (FBOTs) during Phase I of the Zwicky Transient Facility (ZTF). We identify 38 candidates with durations above half-maximum light 1 d ...< t1/2 < 12 d, of which 28 have blue (g-r<-0.2 mag) colors at peak light. Of the 38 transients (28 FBOTs), 19 (13) can be spectroscopically classified as core-collapse supernovae (SNe): 11 (8) H- or He-rich (Type II/IIb/Ib) SNe, 6 (4) interacting (Type IIn/Ibn) SNe, and 2 (1) H&He-poor (Type Ic/Ic-BL) SNe. Two FBOTs (published previously) had high-S/N predominantly featureless spectra and luminous radio emission: AT2018lug and AT2020xnd. Seven (five) did not have a definitive classification: AT 2020bdh showed tentative broad H\(\alpha\) in emission, and AT 2020bot showed unidentified broad features and was 10 kpc offset from the center of an early-type galaxy. Ten (six) have no spectroscopic observations or redshift measurements. We present multiwavelength (radio, millimeter, and/or X-ray) observations for five FBOTs (three Type Ibn, one Type IIn/Ibn, one Type IIb). Additionally, we search radio-survey (VLA and ASKAP) data to set limits on the presence of radio emission for 22 of the transients. All X-ray and radio observations resulted in non-detections; we rule out AT2018cow-like X-ray and radio behavior for five FBOTs and more luminous emission (such as that seen in the Camel) for four additional FBOTs. We conclude that exotic transients similar to AT2018cow, the Koala, and the Camel represent a rare subset of FBOTs, and use ZTF's SN classification experiments to measure the rate to be at most 0.1% of the local core-collapse SN rate.
UVEX is a proposed medium class Explorer mission designed to provide crucial missing capabilities that will address objectives central to a broad range of modern astrophysics. The UVEX design has two ...co-aligned wide-field imagers operating in the FUV and NUV and a powerful broadband medium resolution spectrometer. In its two-year baseline mission, UVEX will perform a multi-cadence synoptic all-sky survey 50/100 times deeper than GALEX in the NUV/FUV, cadenced surveys of the Large and Small Magellanic Clouds, rapid target of opportunity followup, as well as spectroscopic followup of samples of stars and galaxies. The science program is built around three pillars. First, UVEX will explore the low-mass, low-metallicity galaxy frontier through imaging and spectroscopic surveys that will probe key aspects of the evolution of galaxies by understanding how star formation and stellar evolution at low metallicities affect the growth and evolution of low-metallicity, low-mass galaxies in the local universe. Such galaxies contain half the mass in the local universe, and are analogs for the first galaxies, but observed at distances that make them accessible to detailed study. Second, UVEX will explore the dynamic universe through time-domain surveys and prompt spectroscopic followup capability will probe the environments, energetics, and emission processes in the early aftermaths of gravitational wave-discovered compact object mergers, discover hot, fast UV transients, and diagnose the early stages of stellar explosions. Finally, UVEX will become a key community resource by leaving a large all-sky legacy data set, enabling a wide range of scientific studies and filling a gap in the new generation of wide-field, sensitive optical and infrared surveys provided by the Rubin, Euclid, and Roman observatories. This paper discusses the scientific potential of UVEX, and the broad scientific program.
With age, hematopoietic stem cells (HSC) undergo changes in function, including reduced regenerative potential and loss of quiescence, which is accompanied by a significant expansion of the stem cell ...pool that can lead to haematological disorders. Elevated metabolic activity has been implicated in driving the HSC ageing phenotype. Here we show that nicotinamide riboside (NR), a form of vitamin B3, restores youthful metabolic capacity by modifying mitochondrial function in multiple ways including reduced expression of nuclear encoded metabolic pathway genes, damping of mitochondrial stress and a decrease in mitochondrial mass and network-size. Metabolic restoration is dependent on continuous NR supplementation and accompanied by a shift of the aged transcriptome towards the young HSC state, more youthful bone marrow cellular composition and an improved regenerative capacity in a transplant setting. Consequently, NR administration could support healthy ageing by re-establishing a more youthful hematopoietic system.
Broad-spectrum histone deacetylase inhibitors (HDACi) are used clinically as anticancer agents, and more isoform-selective HDACi have been sought to modulate other conditions, including chronic ...inflammatory diseases. Mouse studies suggest that HDACi downregulate immune responses and may compromise host defense. However, their effects on human macrophage antimicrobial responses are largely unknown. Here, we show that overnight pretreatment of human macrophages with HDACi prior to challenge with Salmonella enterica serovar Typhimurium or Escherichia coli results in significantly reduced intramacrophage bacterial loads, which likely reflect the fact that this treatment regime impairs phagocytosis. In contrast, cotreatment of human macrophages with HDACi at the time of bacterial challenge did not impair phagocytosis; instead, HDACi cotreatment actually promoted clearance of intracellular S. Typhimurium and E. coli. Mechanistically, treatment of human macrophages with HDACi at the time of bacterial infection enhanced mitochondrial reactive oxygen species generation by these cells. The capacity of HDACi to promote the clearance of intracellular bacteria from human macrophages was abrogated when cells were pretreated with MitoTracker Red CMXRos, which perturbs mitochondrial function. The HDAC6-selective inhibitor tubastatin A promoted bacterial clearance from human macrophages, whereas the class I HDAC inhibitor MS-275, which inhibits HDAC1 to -3, had no effect on intracellular bacterial loads. These data are consistent with HDAC6 and/or related HDACs constraining mitochondrial reactive oxygen species production from human macrophages during bacterial challenge. Our findings suggest that, whereas long-term HDACi treatment regimes may potentially compromise host defense, selective HDAC inhibitors may have applications in treating acute bacterial infections.
•Unified SQI was developed after 8 years of CA through PCA using 15 soil parameters.•The ZTDSR – ZTM – ZTSMB (+R) system had highest, whereas TPR-CTM had lowest SQI.•The ZTDSR – ZTM – ZTSMB (+R) ...resulted in ∼14 % higher total SOC than the TPR – CTM.•The key indicators were hydraulic conductivity, pH, total N, available P and K.•CA practice maintained higher soil quality and crop yield in rice-mustard system.
The systematic research on the effect of medium-term conservation agriculture (CA) on soil quality, especially under the rice (Oryza sativa L.)-based cropping systems is limited. Hence, the specific objective of the study was to develop soil quality indices with key soil physical, chemical and biological indicators under the conservation and conventional tillage practices in a rice–mustard Brassica juncea (L.) Czern. cropping system. Eight treatment combinations including tillage and crop establishment, crop residue and cropping system intensification with inclusion of short duration summer mungbean Vigna radiata (L.) Wilczek were adopted in rice - mustard cropping system in hot semi-arid, sub-tropical north-western Indo-Gangetic Plains agro-ecoregion of India. Soil samples collected from topsoil (0−5 cm) and 5−15 cm soil layer were analyzed for 15 physical, chemical and biological properties to develop unified soil quality index (SQI) through principal component analysis (PCA). The highest SQI was obtained in the zero till direct seeded rice (ZTDSR) – zero till mustard (ZTM) –ZT summer mungbean (ZTSMB (+R) (mungbean residue in ZTDSR - rice residue in ZTM- mustard residue in ZTSMB) treatment followed by the ZTDSR + BM (brown manuring) – ZTM (+R) (mustard residue in ZTDSR with BM – rice residue in ZTM). The lowest SQI was obtained in transplanted puddled rice (TPR) - conventional till mustard (CTM) for both soil layers. The identified key indicators for SQI in this Inceptisol were saturated hydraulic conductivity (Ks), pH, total N, available P, and available K. Besides, the plots under ZTDSR – ZTM – ZTSMB (+R) resulted in 14 % higher total organic C in topsoil and 28 % higher aggregate stability than the TPR - CTM plots. This ZTDSR – ZTM -ZTSMB (+R) treatment had 65 % higher surface soil microbial biomass C than the TPR – CTM treatment. The ZTDSR – ZTM -ZTSMB (+R) treatment also led to higher Ks, which was in the order of triple ZT > double ZT > ZT > conventional tillage. Thus, the medium-term CA with triple or double zero tillage with crop residue retention could lead to maintain agricultural sustainability under rice-mustard system. Hence, it may be recommended to the farmers for adoption.
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.
Design fixation refers to blind adherence to a set of ideas, which can limit the output of conceptual design. Engineering designers tend to fixate on features of pre-existing solutions and ...consequently generate designs with similar features. The objective of this study is to leverage functional magnetic resonance imaging (fMRI) to study the brain activity of engineering designers during conceptual design in order to understand whether/where design fixation can be detected in a person’s brain when solving design problems. Design solutions indicated that fixation effects were detectable at a statistically significant level. fMRI results show increased activation in areas associated with visuospatial processing when comparing ideation activities using an Example solution to No Example solution. Activation was found in the right inferior temporal gyrus, left middle occipital gyrus, and right superior parietal lobule regions. The left lingual and superior frontal gyri were found to be less active in the example condition; these gyri are close in proximity to the prefrontal cortex, associated with creative output. The spatial patterns of activation provide evidence that a shift in mental resources can occur when a designer becomes fixated. For designers, the timing of ideation relative to the timing of benchmarking existing solutions should be considered.
Exposing cells to excess metal concentrations well beyond the cellular quota is a powerful tool for understanding the molecular mechanisms of metal homeostasis. Such improved understanding may enable ...bioengineering of organisms with improved nutrition and bioremediation capacity. We report here that Chlamydomonas reinhardtii can accumulate manganese (Mn) in proportion to extracellular supply, up to 30-fold greater than its typical quota and with remarkable tolerance. As visualized by X-ray fluorescence microscopy and nanoscale secondary ion MS (nanoSIMS), Mn largely co-localizes with phosphorus (P) and calcium (Ca), consistent with the Mn-accumulating site being an acidic vacuole, known as the acidocalcisome. Vacuolar Mn stores are accessible reserves that can be mobilized in Mn-deficient conditions to support algal growth. We noted that Mn accumulation depends on cellular polyphosphate (polyP) content, indicated by 1) a consistent failure of C. reinhardtii vtc1 mutant strains, which are deficient in polyphosphate synthesis, to accumulate Mn and 2) a drastic reduction of the Mn storage capacity in P-deficient cells. Rather surprisingly, X-ray absorption spectroscopy, EPR, and electron nuclear double resonance revealed that only little Mn2+ is stably complexed with polyP, indicating that polyP is not the final Mn ligand. We propose that polyPs are a critical component of Mn accumulation in Chlamydomonas by driving Mn relocation from the cytosol to acidocalcisomes. Within these structures, polyP may, in turn, escort vacuolar Mn to a number of storage ligands, including phosphate and phytate, and other, yet unidentified, compounds.
In this study, Aluminium 6063 and copper alloy C26000 has been selected, on the basis of industrial utilisation in marine industry like shipbuilding, oil piping system and marine super-structure, for ...joining by Friction Stir Welding and the mechanical properties has been studied upon. Three process parameters have been chosen in the present studies, like tool tilting angle, rpm and weld speed. Taguchi L9 array has been chosen for the experimental methodology and the by varying the selected process parameters, the mechanical properties including the weld efficiency and hardness, in advancing and retreating side, have been studied and compared. The mechanical properties obtained including elongation, yield strength, tensile strength and hardness in the various heat affected zones has been studied to define the utilisation of the FSW process in marine industry.
In this paper, the inhibitory effects of added hydrogen in reactor headspace on fermentative hydrogen production from acidogenesis of glucose by a bacterium, Clostridium acetobutylicum, was ...investigated experimentally in a batch reactor. It was observed that hydrogen itself became an acute inhibitor of hydrogen production if it accumulated excessively in the reactor headspace. A mathematical model to simulate and predict biological hydrogen production process was developed. The Monod model, which is a simple growth model, was modified to take inhibition kinetics on microbial growth into account. The modified model was then used to investigate the effect of hydrogen concentration on microbial growth and production rate of hydrogen. The inhibition was moderate as hydrogen concentration increased from 10% to 30% (v/v). However, a strong inhibition in microbial growth and hydrogen production rate was observed as the addition of H2 increased from 30% to 40% (v/v). Practically, an extended lag in microbial growth and considerably low hydrogen production rate were detected when 50% (v/v) of the reactor headspace was filled with hydrogen. The maximum specific growth rate (µmax), substrate saturation constant (ks), a critical hydrogen concentration at which microbial growth ceased (H2*) and degree of inhibition were found to be 0.976 h−1, 0.63 ± 0.01 gL, 24.74 mM, and 0.4786, respectively.
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