Late Epoch Research Articles

Call for reimagining institutional support for PAR post-COVID

Although we believe academic researchers have a critical role to play in transformative systems change for social and ecological justice, we also argue that academic institutions have been (and continue to be) complicit in colonialism and in racialized, patriarchal capitalism. In this essay, we argue that if academia is to play a constructive role in supporting social and ecological resilience in the late stage Capitalocene epoch, we must move beyond mere critique to enact reimagined and decolonized forms of knowledge production, sovereignty, and structures for academic integrity. We use the pandemic as a moment of crisis to rethink what we are doing as PAR scholars and reflect on our experiences conducting PAR during the pandemic. A framework is presented for the reimaging of institutional support for the embedding of scholars in local social systems. We propose an academy with greater flexibility and consideration for PAR, one with increased funding support for community projects and community engagement offices, and a system that puts local communities first. This reimagining is followed by a set of our accounts of conducting PAR during the pandemic. Each account begins with an author's reflection on their experiences conducting PAR during the pandemic, focusing on how the current university system magnified the impacts of the pandemic. The author's reflection is then followed with a “what if” scenario were the university system changed in such a way that it mitigated or lessened the impacts of the pandemic on conducting PAR. Although this framework for a reimagined university is not a panacea, the reliance on strong in-place local teams, mutually benefiting research processes, and resources for community organizations putting in the time to collaborate with scholars can overcome many of the challenges presented by the pandemic and future crises.

A 2-million-year-old ecosystem in Greenland uncovered by environmental DNA

Late Pliocene and Early Pleistocene epochs 3.6 to 0.8 million years ago1 had climates resembling those forecasted under future warming2. Palaeoclimatic records show strong polar amplification with mean annual temperatures of 11–19 °C above contemporary values3,4. The biological communities inhabiting the Arctic during this time remain poorly known because fossils are rare5. Here we report an ancient environmental DNA6 (eDNA) record describing the rich plant and animal assemblages of the Kap København Formation in North Greenland, dated to around two million years ago. The record shows an open boreal forest ecosystem with mixed vegetation of poplar, birch and thuja trees, as well as a variety of Arctic and boreal shrubs and herbs, many of which had not previously been detected at the site from macrofossil and pollen records. The DNA record confirms the presence of hare and mitochondrial DNA from animals including mastodons, reindeer, rodents and geese, all ancestral to their present-day and late Pleistocene relatives. The presence of marine species including horseshoe crab and green algae support a warmer climate than today. The reconstructed ecosystem has no modern analogue. The survival of such ancient eDNA probably relates to its binding to mineral surfaces. Our findings open new areas of genetic research, demonstrating that it is possible to track the ecology and evolution of biological communities from two million years ago using ancient eDNA.

Geochronology, Geochemistry, and Geodynamic Implications of Permo-Triassic Back-Arc Basin Successions in the North Pamir, Central Asia

Abstract The Permo-Triassic period marks the time interval between Hercynian (Variscan) orogenic events in the Tien Shan and the North Pamir, and the Cimmerian accretion of the Gondwana-derived Central and South Pamir to the southern margin of the Paleo-Asian continent. A well-preserved Permo-Triassic volcano-sedimentary sequence from the Chinese North Pamir yields important information on the geodynamic evolution of Asia’s pre-Cimmerian southern margin. The oldest volcanic rocks from that section are dated to the late Guadalupian epoch by a rhyolite and a dacitic dike that gave zircon U-Pb ages of ~260 Ma. Permian volcanism was largely pyroclastic and mafic to intermediate. Upsection, a massive ignimbritic crystal tuff in the Chinese Qimgan valley was dated to 244.1±1.1 Ma, a similar unit in the nearby Gez valley to 245±11 Ma, and an associated rhyolite to 233.4±1.1 Ma. Deposition of the locally ~200 m thick crystal tuff unit follows an unconformity and marks the onset of intense, mainly mafic to intermediate, calc-alkaline magmatic activity. Triassic volcanic activity in the North Pamir was coeval with the major phase of Cimmerian intrusive activity in the Karakul-Mazar arc-accretionary complex to the south, caused by northward subduction of the Paleo-Tethys. It also coincided with the emplacement of basanitic and carbonatitic dikes and a thermal event in the South Tien Shan, to the north of our study area. Evidence for arc-related magmatic activity in a back-arc position provides strong arguments for back-arc extension or transtension and basin formation. This puts the Qimgan succession in line with a more than 1000 km long realm of extensional Triassic back-arc basins known from the North Pamir in the Kyrgyz Altyn Darya valley (Myntekin formation), the North Pamir of Tajikistan and Afghanistan, and the Afghan Hindukush (Doab formation) and further west from the Paropamisus and Kopet Dag (Aghdarband, NE Iran).

Photometric and Spectroscopic Observations of GRB 210104A: Bright Reverse-shock Emission and Dense Circumburst Environment

Early afterglow observations of gamma-ray bursts (GRBs) are valuable for exploring the properties of their jets and ambient medium. We report our photometric and spectroscopic observations of GRB 210104A and discuss its jet properties with multiwavelength data. Our spectroscopic observation reveals several absorption features and a tentative redshift of 0.46 is identified. A bright optical flare that has a peak brightness of R = 13 mag at 112 ± 7 s was observed in the R band during 67 ∼ 165 s post the GRB trigger. The flux of the R-band afterglow decays with a slope of α O = − 0.91 ± 0.03 at t > 650 s. The early X-ray afterglow lightcurve is a smooth bump, and it decays with a slope of α X = −1.18 ± 0.01 at late epoch. Our joint spectral fit to the optical-X-ray afterglows during (1.1–1.3) × 104 s yields a photon index ΓO,X = −1.82 ± 0.04. The derived host galaxy extinction is A R = 0.87. Attributing the early optical flare to the reverse-shock (RS) emission and the late optical-X-ray emission to the forward shock emission, the optical and X-ray lightcurves at t < 3 × 104 s can be well fit adopting a Markov Chain Monte Carlo algorithm. Comparing the properties of GRB 210104A with other GRBs that have detection of bright RS emission, we show that its jet is mildly magnetized (R B = 28), with high radiation efficiency (77%), is subenergetic (E k,iso = 4.5 × 1051 erg), and moderately relativistic (Γ0 ∼ 35) in a density medium (n 0 ∼ 417 cm−3). It follows the tight L γ,iso–E p,z–Γ0 relation as with typical GRBs.

New insights on the Late Quaternary evolution of Abrolhos reefs, Eastern Brazilian Shelf

The Abrolhos shelf, in the eastern Brazilian margin, encompasses the largest reef province in the South Atlantic, characterised by low coral diversity and a high level of endemism. Knowledge gaps about how the Abrolhos coastal reefs evolved, during the post LGM and MIS 6/MIS 5, favoured a paradigm that is revisited in the light of new data. Here, new data from two new, long boreholes (20 and 50 m-long) are presented in order to investigate and provide new insights into the evolution of two shallow reefs on the Abrolhos Shelf during the late Pleistocene and Holocene epochs. Results show that Holocene and Pleistocene reefs grew on highly turbid waters with a significant terrigenous sediment input. Corals and CCA assemblages were identified as main framework builders of Abrolhos inner-shelf reefs since the Pleistocene. No clear shallowing upward sequence of reef builders was observed, which differs from other reef sequences all over the world. In terms of Holocene reef growth, Pedra Grande and Coroa Vermelha reefs turned on roughly coevally at different depths and with different coral assemblages. Pedra Grande reef started growing circa 6.8 kyr BP in a water depth approximately 10 m deeper than Coroa Vermelha, which started growing around 6.4 kyr BP, but Coroa Vermelha turned off at around 4 kyr BP, while Pedra Grande kept growing until around 1.2 kyr BP. This novel reef stratigraphy data provided a new insight on the evolution of the Abrolhos coastal reefs, showing that different environmental and topographic controls could have acted spatially in different ways. Coroa Vermelha reef seems to have started its growth as a result of a topographic high control. Pedra Grande reef seems to be connected to a broader submerged reef setting and started to grow in deeper water depths. The presence of three reef arcs in Abrolhos is proposed, including a submerged reef arc.

Early and late time cosmology: the f(R) gravity perspective

Discrepancies between observations at early and late cosmic epochs, and the vacuum energy problem associated with the interpretation of cosmological constant, are questioning the $\Lambda$CDM model. Motivated by these conceptual and observational facts, extensions of Einstein's gravity are recently intensively considered in view of curing unsolved issues suffered by General Relativity at ultraviolet and infrared scales. Here, we provide a short overview of some aspects of $f(R)$ gravity, focusing, in particular, on cosmological applications. Specifically, Noether symmetries are adopted as a criterion to select viable models and investigate the corresponding dynamics. We thus find solutions to the cosmological field equations, analyzing the behaviour of selected models from the matter-dominated to the present epoch. Moreover, constraints coming from energy conditions and the so-called swampland criteria are also considered. In particular, we qualitatively discuss the possibility of $f(R)$ gravity to account for fixing cosmic tensions.

Shedding light on the timing of the largest Late Quaternary transgression of the Caspian Sea

The Late Quaternary history of the Caspian Sea remains controversial. One of the major disagreements in this debate concerns the stratigraphic correlation of various deposits in the Caspian Basin. In this paper we identify and date, for the first time, the Enotaevka regression, lying between the two major phases of the largest Late Quaternary Caspian Sea transgression, the Khvalynian transgressive epoch, and provide a minimum estimate of sea level decrease during this regression. The River Volga is the major source of water to the Caspian; the Lower Volga region is unique in its record of palaeogeographic events, and this provides the opportunity to build a single stratigraphic and palaeogeographic history for the Pleistocene of Central Eurasia. Here we use luminescence to establish a new chronology for the largest Late Quaternary transgressive epoch of the Caspian Sea. The existing radiocarbon chronology does not allow the resolution of the two transgressive phases of this epoch (Early and Late Khvalynian). Based on clear palaeontological and geomorphological evidence, these must be very different in age, but shells associated with both transgressions gave very scattered ages of between 8 and 50 ka. This ambiguity has led to considerable discussion concerning the existence or otherwise of a deep Enotaevka regression phase between the two Khvalynian transgressions. Recently we have again identified these deposits at Kosika, on the right valley side of the Volga River. The new luminescence chronology described here, based on quartz OSL and K-feldspar pIRIR 290 ages, allows us to reconstruct the complicated history of Late Quaternary sedimentation in the southern part of the Lower Volga valley. The Kosika section reflects the following major stages: (1) the earlier Khazarian transgressive epoch; (2) a decrease in the sea level with the development of a freshwater lake/lagoon in the Volga valley; and (3) the Khvalynian transgressive-regressive epoch, including both the Early and Late Khvalynian transgressive periods, and the intercalated Enotaevka regression. Sea level during the early stage of the Khvalynian transgression reached Kosika at about 23–22 ka (approx. −1 to −2 m asl). This event is of the same age as the “grey clay” strata at the base of the Leninsk section marine unit (Kurbanov et al., 2021), also formed at the beginning of the Early Khvalynian transgression. Around 15–14 ka the Khvalynian basin moved to a regressive stage, and in the northern part of the Lower Volga the top part of the well-known ‘Chocolate Clay’ accumulated. In the southern part of the valley marine accumulation stopped at about 12–13 ka. This allows us to reconstruct a decrease in Early Khvalynian basin sea level between 15–14 ka and 13–12 ka ago, of about ∼15 m. At the Kosika section sediments derived from the Enotayevka regression are visible as a weakly developed palaeosol with evidence of surficial erosion, and these sediments are now dated to 13–12 ka. At 8.6 ± 0.5 ka, during the period of the Mangyshlak regression, aeolian deflation processes reworked sediments deposited by immediately preceding Late Khvalynian transgression.

Empirical H/V spectral ratios at the InSight landing site and implications for the martian subsurface structure

SUMMARY The horizontal-to-vertical (H/V) spectral ratio inversion is a traditional technique for deriving the local subsurface structure on Earth. We calculated the H/V from the ambient vibrations at different wind levels at the InSight landing site, on Mars, and also computed the H/V from the S-wave coda of the martian seismic events (marsquakes). Different H/V curves were obtained for different wind periods and from the marsquakes. From the ambient vibrations, the recordings during low-wind periods are close to the instrument self-noise level. During high-wind periods, the seismic recordings are highly contaminated by the interaction of the lander with the wind and the martian ground. Therefore, these recordings are less favourable for traditional H/V analysis. Instead, the recordings of the S-wave coda of marsquakes were preferred to derive the characteristic H/V curve of this site between 0.4 and 10 Hz. The final H/V curve presents a characteristic trough at 2.4 Hz and a strong peak at 8 Hz. Using a full diffuse wavefield approach as the forward computation and the Neighbourhood Algorithm as the sampling technique, we invert for the 1-D shear wave velocity structure at the InSight landing site. Based on our inversion results, we propose a strong site effect at the InSight site to be due to the presence of a shallow high-velocity layer (SHVL) over low-velocity units. The SHVL is likely placed below a layer of coarse blocky ejecta and can be associated with Early Amazonian basaltic lava flows. The units below the SHVL have lower velocities, possibly related to a Late Hesperian or Early Amazonian epoch with a different magmatic regime and/or a greater impact rate and more extensive weathering. An extremely weak buried low velocity layer (bLVL) between these lava flows explains the data around the 2.4 Hz trough, whereas a more competent bLVL would not generate this latter feature. These subsurface models are in good agreement with results from hammering experiment and compliance measurements at the InSight landing site. Finally, this site effect is revealed only by seismic events data and explains the larger horizontal than vertical ground motion recorded for certain type of marsquakes.

Dynamic auditory contributions to error detection revealed in the discrimination of Same and Different syllable pairs

During speech production auditory and motor regions within the sensorimotor dorsal stream operate in concert to facilitate online error detection. As the dorsal stream also is known to activate in speech perception, the purpose of the current study was to probe the role of auditory regions in error detection during auditory discrimination tasks as stimuli are encoded and maintained in working memory. A priori assumptions are that sensory mismatch (i.e., error) occurs during the discrimination of Different (mismatched) but not Same (matched) syllable pairs. Independent component analysis was applied to raw EEG data recorded from 42 participants to identify bilateral auditory alpha rhythms, which were decomposed across time and frequency to reveal robust patterns of event related synchronization (ERS; inhibition) and desynchronization (ERD; processing) over the time course of discrimination events. Results were characterized by bilateral peri-stimulus alpha ERD transitioning to alpha ERS in the late trial epoch, with ERD interpreted as evidence of working memory encoding via Analysis by Synthesis and ERS considered evidence of speech-induced-suppression arising during covert articulatory rehearsal to facilitate working memory maintenance. The transition from ERD to ERS occurred later in the left hemisphere for Different trials than for Same trials, with ERD and ERS temporally overlapping during the early post-stimulus window. Results were interpreted to suggest that the sensory mismatch (i.e., error) arising from the comparison of the first and second syllable elicits further processing in the left hemisphere to support working memory encoding and maintenance. Results are consistent with auditory contributions to error detection during both encoding and maintenance stages of working memory, with encoding stage error detection associated with stimulus concordance and maintenance stage error detection associated with task-specific retention demands.

Age, Genesis and Tectonic Setting of the Sayashk Tin Deposit in the East Junggar Region: Constraints from Lu–Hf Isotopes, Zircon U–Pb and Molybdenite Re–Os Dating

The Sayashk tin (Sn) deposit is located within the southern part of the Eastern Junggar orogenic belt in Xinjiang Province and forms part of the Kalamaili alkaline granite belt. There are many Sn polymetallic deposits in the area. To constrain the age, genesis, and tectonic setting of the Sayashk tin deposit in the East Junggar region, we conducted a bulk-rock geochemical analysis of the granite porphyry (SR1) and medium- to fine-grained granite (SR2) hosts of the deposit, LA-ICP-MS zircon U–Pb dating and Lu–Hf isotopic analysis, as well as molybdenite Re–OS dating and combined our results with the metallogenic conditions and other geological characteristics of the deposit. The results show that the Sayashk Sn deposit is indeed spatially, temporally, and genetically closely related to the granite porphyry and medium-fine-grained granite. Both zircon U–Pb ages are 308.2 ± 1.5 Ma and 310.9 ± 1.5 Ma, respectively. The isochron age of molybdenite is 301.4 ± 6.7 Ma, which represents the crystallization age of the granite porphyry and medium-fine-grained granite. Therefore, all of them formed in the late Carboniferous epoch. The medium-fine-grained granites and granite porphyry are characteristically rich in Si and alkali, poor in Ca and Mg, rich in high field-strength elements (HFSE, e.g., Zr, Hf) and Ce, and deficient in Ba, Sr, Eu, P, and Ti. They are typical A-type granites, showing the characteristics of a mixed crustal mantle source. The εHf(t) values of the zircon from the granite porphyry (SR1) range from 10.27 to 16.17 (average 13.71), εHf(t) values of the zircon from the medium-fine-grained granites (SR2) are between 5.72 and 9.21 (average 7.08), and the single model ages (TDM1) and two-stage model ages (TDM2) of the granite porphyry (SR1) fall within the ranges of 319~535 Ma and 339~644 Ma. The single model ages (TDM1) and two-stage model ages (TDM2) of the medium-fine-grained granites (SR2) fall within the ranges of 346~479 Ma and 309~557 Ma. There is little difference between their two-stage model ages and zircon U–Pb ages, indicating that the Sayashk granite may be the product of partial melting of juvenile crustal. Combined with previous research results, the Sayashk Sn deposit formed in a post-collision extensional tectonic setting after the late Carboniferous in the Kalamaili area.

How baryons affect haloes and large-scale structure: a unified picture from the Simba simulation

ABSTRACT Using the state-of-the-art suite of hydrodynamic simulations Simba, as well as its dark-matter-only counterpart, we study the impact of the presence of baryons and of different stellar/AGN feedback mechanisms on large-scale structure, halo density profiles, and on the abundance of different baryonic phases within haloes and in the intergalactic medium (IGM). The unified picture that emerges from our analysis is that the main physical drivers shaping the distribution of matter at all scales are star formation-driven galactic outflows at z &amp;gt; 2 for lower mass haloes and AGN jets at z &amp;lt; 2 in higher mass haloes. Feedback suppresses the baryon mass function with time relative to the halo mass function, and it even impacts the halo mass function itself at the ∼20 per cent level, particularly evacuating the centres and enhancing dark matter just outside haloes. At early epochs baryons pile up in the centres of haloes, but by late epochs and particularly in massive systems gas has mostly been evacuated from within the inner halo. AGN jets are so efficient at such evacuation that at low redshifts the baryon fraction within ∼1012–1013 M⊙ haloes is only 25 per cent of the cosmic baryon fraction, mostly in stars. The baryon fraction enclosed in a sphere around such haloes approaches the cosmic value Ωb/Ωm only at 10–20 virial radii. As a result, 87 per cent of the baryonic mass in the Universe lies in the IGM at z = 0, with 67 per cent being in the form of warm-hot IGM (T &amp;gt; 105K).

Cogenesis of Baryon asymmetry and gravitational dark matter from primordial black holes

We propose a scenario where dark matter (DM) with a wide mass range from a few keV to PeV can be produced solely from evaporating primordial black holes (PBH), while being consistent with the required free streaming length for structure formation. If DM does not have any other interactions apart from gravity and the universe has a PBH dominated phase at early epoch, then PBH evaporation typically leads to overproduction of DM in this mass range. By incorporating this gravitational DM within a Type-I seesaw scenario with three right handed neutrinos (RHN), we bring the abundance of PBH generated DM within observed limits by late entropy injection due to decay of one of the RHNs, acting as the diluter. The diluter, due to its feeble coupling with the bath particles, gets produced primarily from the PBH evaporation thereby leading to the second stage of early matter domination after the end of PBH dominated era. The other two RHNs contribute to the origin of light neutrino mass and also lead to the observed baryon asymmetry via leptogenesis with contributions from both thermally and PBH generated RHNs. The criteria of DM relic and baryon asymmetry can be satisfied simultaneously if DM mass gets restricted to a ballpark in the MeV-GeV regime with the requirement of resonant leptogenesis for heavier DM mass in order to survive the large entropy dilution at late epochs.

Age and Petrogenesis of Ultramafic Lamprophyres of the Arbarastakh Alkaline-Carbonatite Complex, Aldan-Stanovoy Shield, South of Siberian Craton (Russia): Evidence for Ultramafic Lamprophyre-Carbonatite Link

Abstract In this study, we discuss mineral chemistry data, melt inclusion study results, and report Ar–Ar phlogopite age for the aillikite dikes of the Arbarastakh alkaline-carbonatite complex on the Aldan-Stanovoy shield, Russia. Aillikite was crystallized at 631 ± 8.5 Ma, coeval with the intrusion age of the Arbarastakh rocks. The Arbarastakh complex was formed during the late Neoproterozoic epoch of rare earth element-Nb ore-bearing alkaline-carbonatite magmatic activity that was widespread on the southwestern and southern margins of the Siberian craton, related to rifting processes during the breakup of the supercontinent Rodinia. The aillikites show mineralogical characteristics of primitive magmas such as highly forsteritic olivine, Mg-ilmenite, and Cr-rich spinel. The variance in olivine zonation, morphologies, and chemical element distribution indicate that olivine in the aillikites is represented by several genetic types: xenogenic olivines (Fe-poor cores) from the sheared peridotite, olivine antecrysts (Fe-rich cores) related to mantle metasomatism by preceding proto-aillikite melt, and olivine phenocrysts formed during crystallization of aillikite melt. The latter shows decreasing Ni and Cr due to fractional crystallization of olivine, ilmenite, and chromite, along with increasing Mn and Ca concentrations that are consistent with enrichment of these elements in the residual melt. The olivine phenocrysts chemistry shows variations that are characteristic of the presence of phlogopite and carbonate in the mantle source (low 100*Ca/Fe (0.4–1.2) and 100*Mn/Fe (1–2), moderate 100*Ni/Mg (1.4–0.4)). Spinel shows a wide compositional variation with two compositional zoning trends, one of which follows the titanomagnetite trend, while the other follows the qandilite-rich magnesio-ulvöspinel-magnetite one. The latter trend indicates an increase in fO2 and attendant Fe oxidation to Fe3+ during crystallization. Ilmenite composition evolution (from Mg-rich to Mn-rich) also reflects the carbonate-rich nature of aillikite melt. We identify primary melt inclusions hosted in phlogopite and secondary melt inclusions in olivine; both melt inclusions types have daughter minerals dominated by dolomite, calcite, Na-Ca carbonates, phosphates, and phlogopite, consistent with the carbonate-rich nature of aillikite melt. The calculated temperatures reflect the early stage of aillikite crystallization, with values ranging from 1169 to 1296°C and fO2 values (olivine-spinel pair) varying from +0.40 to +1.03 ΔFMQ and from ΔNNO −0.9 to ΔNNO −2.0 (perovskite oxygen barometer); in contrast, the homogenization temperature of the secondary melt inclusions in olivine (700–720°C) characterizes late-stage aillikite melt evolution. The carbonate-rich nature of the Arbarastakh aillikite and its similar age to the carbonatites are consistent with a genetic relationship between them.

Study of gravitational collapse for anisotropic Karmarkar star in minimally coupled [formula omitted] gravity

The current study investigates a class of an exact analytical solutions of shear-free and spherically symmetric gravitational collapse of Karmarkar star in the minimally coupled f(R) theory of gravity by incorporating the properties of anisotropic radiating matter. The collapse onsets from an early static configuration obeying the class 1 Karmarkar approach and progresses with dissipation of immense energy in the form of outgoing radiation and radial heat flux. We have formulated the f(R) field equations under the specified Karmarkar approach and extracted dynamical evolution equation through the boundary matching hypersurface between the exterior Vaidya solution of radiative star and the interior spacetime. We have analyzed our solutions for a system of field equations with two specific f(R) models like f(R)=R+ηR2 and f(R)=R+ηR(R+ϵR2), which are famous and cosmologically viable for the present and the late epoch of cosmic inflation. The physical viability of the proposed solutions has manifested in various graphical plots via material variables, stability tests, anisotropy of pressure, effective mass, compactness, energy conditions and relaxational effects through temporal profile. These phenomenological evidences ensure the viable physical conduct of our radiative star model that seems in good agreement with the possible features of gravitational collapse (GC).

Tale of GRB 171010A/SN 2017htp and GRB 171205A/SN 2017iuk: Magnetar origin?

We present late-time optical follow-up observations of GRB 171010A/SN 2017htp (z = 0.33) and low-luminosity GRB 171205A/SN 2017iuk (z = 0.037) acquired using the 4K×4K CCD Imager mounted at the 3.6 m Devasthal Optical Telescope (3.6 m DOT) along with the prompt emission data analysis of these two interesting bursts. The prompt characteristics (other than brightness) such as spectral hardness, T90, and minimum variability time-scale are comparable for both the bursts. The isotropic X-ray and kinetic energies of the plateau phase of GRB 171205A are found to be less than the maximum energy budget of magnetars, supporting magnetar as a central engine powering source. The new optical data of SN 2017htp and SN 2017iuk presented here, along with published ones, indicate that SN 2017htp is one of the brightest and SN 21017iuk is among the faintest GRB associated SNe (GRB–SNe). Semi-analytical light-curve modelling of SN 2017htp, SN 2017iuk and only known GRB associated superluminous supernova (SLSN 2011kl) are performed using the MINIM code. The model with a spin-down millisecond magnetar as a central engine powering source nicely reproduced the bolometric light curves of all three GRB–SNe mentioned above. The magnetar central engines for SN 2017htp, SN 2017iuk, and SLSN 2011kl exhibit values of initial spin periods higher and magnetic fields closer to those observed for long GRBs and H-deficient SLSNe. Detection of these rare events at such late epochs also demonstrates the capabilities of the 3.6 m DOT for deep imaging considering longitudinal advantage in the era of time-domain astronomy.

Can the other Speak? A representation of Otherness in Elif Shafak's Bastard of Istanbul

Being a third world woman, Gayatri Spivak has embodied her idea about the marginalized, the others, or the outliers, in a way that caught the attention of both supporters and opponents. She seeks self-realization such as empowering women in their society and establishing identity for outsiders and ethnic minorities, in addition to liberation from patriarchal restrictions in most societies. Identity has gotten more complex and convoluted because of modernism in this late epoch. This phenomenon occurs because the complexity and insecurity of identity are commonly considered to be permeated by the huge changes in human life's social condition As a result, the quick flux of identity might be seen as endangering the stability of identity itself, especially in the age of contemporary technology, migration, urbanization, and globalization in which people today live. Identity and its relationship to social recall in heterogeneous culture is the central topic of The Bastard of Istanbul which depicts how Turkey has forgotten the societal memory of the Armenian Genocide, which is seen as a backdrop to Turkey's violent past, by showing people with contradictory identities as Turks and Armenian Americans who continue to deny on one hand, and on the other, they are looking for their affiliation. The goal of this study is to illustrate how to treat the forcibly displaced as they are outsiders according to their country and as they are others according to the countries they inhabit, depicting their lost between their roots and origins and the second identity they hold.

Late Cretaceous Diatoms (Bacillariophyta) from the Teshio-Nakagawa Area, Hokkaido, Northern Japan: Significance for Their Origin and Biostratigraphy

Well-preserved marine diatoms are documented for the first time from authigenic carbonate rocks induced by cold methane (hydrocarbon) seepage in the Omagari Formation (latest Santonian to earliest Campanian in age, Late Cretaceous Epoch; around 83.6 Ma) of the upper part of the Yezo Group in the Teshio-Nakagawa area, northern Hokkaido (northern Japan). The diatom flora is rich in species of Hemiaulus and Triceratium, associated with a few other extinct diatom genera. An araphid genus (Sceptroneis) was also observed; this is one of the earliest fossil records of “pennate” (Bacillariophyceae) diatoms. Although valve ultrastructures have been mostly dissolved, the preservation of these diatoms is much better than that in the few previous reports of Cretaceous siliceous photosynthetic organisms from Japan and adjacent regions in the northwestern Pacific Ocean. Because of their common generic composition in the mid- to high-latitude regions in both hemispheres, diatoms are suggested to have experienced a global radiation by early Campanian time. Thus, our diatom records provide insights into the Late Cretaceous floral adaptive radiation around the northwestern Pacific margin, where the radiation history of diatoms is yet unclear. As Gladius antiquus was confirmed but Basilicostephanus species were absent from the present material, the flora from the Teshio-Nakagawa area is tentatively regarded as belonging to the G. antiquus Concurrent Range Zone, an interval extending from an undetermined Late Cretaceous Epoch to the latest Santonian Age. However, this floral correlation is inaccurate because our materials are latest Santonian to earliest Campanian in age, as dated by the molluscan (ammonoids and inoceramids) biostratigraphy. Hence, further research is required to clarify the sensitivity of different chronological proxies and the stratigraphic ranges of age-diagnostic diatoms in different geographic provinces.

Unifying inflation with early and late dark energy with multiple fields: Spontaneously broken scale invariant two measures theory

A unified multi scalar field model with three flat regions is discussed. The three flat regions are the inflation, early and late dark energy epochs. The potential is obtained by a spontaneous breaking of scale invariance generated by Non Riemannian Measures of integration (or Two Measures Theories (TMT)).We define the scale invariant couplings of the scalar fields to the different measures through exponential potentials. Spontaneous breaking of scale invariance takes place when integrating the fields that define the measures. When going to the Einstein frame we obtain: (i) An effective potential for the scalar fields with three flat regions which allows for a unified description of both early universe inflation (in the higher energy density flat region) as well as of present dark energy epoch which can be realized with a double phase, i.e., in two flat regions. (ii) In the slow roll inflation, only one field combination the ``dilaton", which transforms under scale transformations, has non trivial dynamics, the orthogonal one, which is scale invariant remains constant. (iv) In the late universe we define scale invariant couplings of Dark Matter to the dilaton. These couplings define a matter induced potential for the dilaton and extremizing this potential determines the scale invariant scalar field, while all exotic non canonical behavior of the Dark Matter as well as any possible $5^{th}$ force disappear. (v) We calculate the evolution of the late universe under these conditions with the realization of two different possible realizations of $\Lambda$CDM type scenarios depending of the flat region in the late universe. These two phases could appear at different times in the history of the universe.(vi) From the Planck data, we find the constraints on the parameters during the inflationary epoch and these values are used to obtain constraints relevant to the present epoch.

A new pan-kinosternid, Leiochelys tokaryki, gen. et sp. nov., from the late Maastrichtian Frenchman formation, Saskatchewan Canada.

Previously, only a single member of Pan-Kinosternidae (Yelmochelys rosarioae) had been documented from the Late Cretaceous epoch. In this report we describe a new pan-kinosternid genus and species, herein named Leiochelys tokaryki, based on a nearly complete, articulated skeleton from the Late Cretaceous (Maastrichtian) Frenchman Formation of Saskatchewan, Canada. L. tokaryki differs most notably from the previously described Y. rosarioae in having triangular plastral lobes, and in that the suture between the hyo- and hypoplastron is in line with the suture between the fifth and sixth peripherals. A maximum parsimony analysis suggests that L. tokaryki is intermediate between Y. rosarioae and crown-group kinosternids. Kinosternid features present in L. tokaryki include the presence of a reduced plastral bridge that extends from the posterior tip of peripheral 4 to the anterior tip of peripheral 7, two inframarginals that contact one another, a smooth triturating surface, and participation of the palatine in the triturating surface. An unexpected feature of the skull is the presence of a large stapedial canal, suggesting that the decrease in size of the stapedial canal and increase in the canalis caroticus cerebralis occurred independently in Dermatemydidae and Kinosternidae. The character-states of the skull and skeleton of L. tokaryki indicate that morphological changes occurring during the diversification of Kinosternoidea were more complex than expected based on data from derived members of the group.

Distinct Thermal Emission from GRB 190109A

The gamma-ray bursts (GRBs) with distinct thermal components are rarely detected, especially in cases with thermal components throughout the prompt phase. Recently, Fermi/GBM, Swift/BAT, and Swift/XRT detected the special long-duration GRB 190109A, which has four pulses in the prompt gamma-ray emission, i.e, Pulse I (−4 to 20 s), Pulse II (20–50 s), Pulse III (50–90 s), and Pulse IV (90–120 s). GRB 190109A exhibits a very hard low-energy index (α ∼ 1) in the Band function relative to the typical GRBs (α ∼ − 1). In the whole burst prompt emission, we find distinct thermal emissions in the time-resolved spectra throughout four pulses. The blackbody (BB) temperature kT varies from 24.7 to 8.2 keV for Pulse I to Pulse IV. We also obtain the relation of F ∝ kT −0.40 for the early phase (Pulse I) and F ∝ kT 3.33±0.76 for the late phase (Pulses II–IV), respectively. The significant deviation of the kT − F relation in the early epochs from that in the late epochs likely suggests that the BB spectra origin of the early phase (Pulse I) may have disparate physical processes from those of the late phase (Pulses II–IV). For instance, it may be the transition from cocoon surroundings by a jet to the photosphere of the matter-dominated jet. A jet break is found in the late X-ray afterglow, which is in keeping with the standard external shock afterglow model in the interstellar medium circumburst.