Multiwavelength extragalactic nuclear transients, particularly those detectable as multi-messengers, are among the primary drivers for the next-generation observatories. X-ray quasi-periodic ...eruptions (QPEs) are the most recent and perhaps most peculiar addition to this group. Here, we report a first estimate of the volumetric rate of QPEs based on the first four discoveries with the eROSITA X-ray telescope onboard the Spectrum Roentgen Gamma observatory. Under the assumption, supported by a suite of simulated light curves, that these four sources sample the intrinsic population somewhat homogeneously, we correct for their detection efficiency and compute a QPE abundance of R vol = 0.60 −0.43 +4.73 × 10 −6 Mpc −3 above an intrinsic average log L 0.5−2.0 keV peak > 41.7. Since the exact lifetime of QPEs ( τ life ) is currently not better defined than between a few years or few decades, we convert this to a formation rate of ℛ vol / τ life ≈ 0.6 × 10 −7 ( τ life /10 yr) −1 Mpc −3 yr −1 . As a comparison, this value is a factor ∼10 τ life times smaller than the formation rate of tidal disruption events. The origin of QPEs is still debated, although lately most models suggest that they are the electromagnetic counterpart of extreme mass ratio inspirals (EMRIs). In this scenario, the QPE rate would thus be the first ever constraint (i.e. a lower limit) to the EMRI rate from observations alone. Future discoveries of QPEs and advances in their theoretical modeling will consolidate or rule out their use for constraining the number of EMRIs detectable by the LISA mission.
Visual representations play a critical role in enhancing science, technology, engineering, and mathematics (STEM) learning. Educational psychology research shows that adding visual representations to ...text can enhance students' learning of content knowledge, compared to text-only. But should students learn with a single type of visual representation or with multiple different types of visual representations? This article addresses this question from the perspective of the representation dilemma, namely that students often learn content they do not yet understand from representations they do not yet understand. To benefit from visual representations, students therefore need representational competencies, that is, knowledge about how visual representations depict information about the content. This article reviews literature on representational competencies involved in students' learning of content knowledge. Building on this review, this article analyzes how the number of visual representations affects the role these representational competencies play during students' learning of content knowledge. To this end, the article compares two common scenarios: text plus a single type of visual representations (T+SV) and text plus multiple types of visual representations (T+MV). The comparison yields seven hypotheses that describe under which conditions T+MV scenarios are more effective than T+SV scenarios. Finally, the article reviews empirical evidence for each hypothesis and discusses open questions about the representation dilemma.
Abstract
Studies on Akdala rice system found that rice plants sensitive to meteorological conditions. Climate change leads to changes in crop structure. The temperature of the rice field air and ...water has a special influence on the structure of the rice crop. It is established that the temperature of the water layer in rice paddies in the irrigation period does not exceeds 29
0
C, which is below the threshold of 35
0
C, when the flow and discharge of water from the paddies are recommended. The temperature of water in rice paddies, the surface layer was determined by an express thermometer, at the depth of the water layer 5, 10, 15 and 20 cm by Savin Thermometers, soil – thermometers TM-5.
We analyze linear, weakest-link and best-shot public goods games where a distinguished team member, the team allocator, has property rights over the benefits from the public good to distribute it ...among team members. Our team allocator games are intended to capture natural asymmetries in hierarchical teams facing social dilemmas, such as those in work teams. We show that introducing a team allocator leads to increased contributions in linear and best-shot public-good games. No effect can be found in the weakest-link public good. The team allocator uses her power to distribute benefits in a way that motivates people to contribute. Re-allocating team payoffs allows her to reward contributing team members and to sanction non-cooperating members at no efficiency losses from explicit sanctioning costs. Thus, team profits are higher in the linear team allocator game but not in the best-shot case, where coordination problems lower the welfare for the remaining team members.
Oxidative stress occurs when generation of reactive oxygen species (ROS) overwhelms antioxidant defenses. Oxidative stress has been associated with male infertility. The transcription factor nuclear ...factor-erythroid 2-related factor 2 (NRF2) regulates basal and inducible transcription of genes encoding enzymes important for protection against ROS. We hypothesized that deletion of the
Nrf2 gene causes testicular and epididymal oxidative stress, which disrupts spermatogenesis. Our results show that male
Nrf2
−/− mice have decreased fertility compared to wild-type and heterozygous littermates, due to accumulating seminiferous tubule damage with increasing age. Testicular sperm head counts, epididymal sperm counts, and epididymal sperm motility in 2-month-old
Nrf2
−/− males did not differ from those of wild-type littermates; however, by age 6
months,
Nrf2
−/− males had 44% lower testicular sperm head counts, 65% lower epididymal sperm counts, and 66% lower epididymal sperm motility than wild-type males. Two- to 4-month-old
Nrf2
−/− males had elevated levels of testicular and epididymal lipid peroxidation and testicular germ cell apoptosis, and decreased levels of antioxidants, compared to wild-type males. These results provide evidence that oxidative stress has deleterious effects on the testis and epididymis and demonstrate a critical role for the transcription factor NRF2 in preventing oxidative disruption of spermatogenesis.
This work considers combinatorial designs in terms of the algebra of quantum spins, providing insights and techniques useful to both. The number 15 that is central to a famous problem of classical ...design theory, with origins in a recreational puzzle nearly two centuries old, coincidentally equals the number of basic operators of two quantum spins (“qubits”). This affords a 1:1 correspondence that we exploit to use the well-known Pauli spin or Lie–Clifford algebra of those 15 operators to provide specific constructions for that recreational problem. An algorithm is set up that, working with four basic operators conveniently rendered in a two-bit binary, generates solutions to quantum states. They can be mapped into four base colors or various tonal scales, thus leading to visual or acoustic realizations of each design. The Fano plane of finite projective geometry involving seven points and lines of an equilateral triangle, and the tetrahedron (a “three-dimensional simplex” of 15 points) are key objects in this study. They simplify the handling of two-qubit operator algebra and may be useful in wide contexts in the field of quantum information. In particular, the seven-parameter sub-algebra describes also what have been called X-states which, while being a subset of all two-qubit states, still embrace a wide variety of quantum correlations including entanglement and quantum discord. Extension to
n
qubits and higher-dimensional “qudits” with similar mappings of them to combinatorial designs and finite projective geometries is indicated.
ABSTRACT
The ROSAT-selected tidal disruption event (TDE) candidate RX J133157.6−324319.7 (J1331) was detected in 1993 as a bright 0.2–2 keV flux of (1.0 ± 0.1) × 10−12 erg s−1 cm−2, ultra-soft (kT = ...0.11 ± 0.03 keV) X-ray flare from a quiescent galaxy (z = 0.051 89). During its fifth all-sky survey (eRASS5) in 2022, Spectrum-Roentgen-Gamma (SRG)/ eROSITA detected the repeated flaring of J1331, where it had rebrightened to an observed 0.2–2 keV flux of (6.0 ± 0.7) × 10−13 erg s−1 cm−2, with spectral properties (kT = 0.115 ± 0.007 keV) consistent with the ROSAT-observed flare ∼30 yr earlier. In this work, we report on X-ray, ultraviolet, optical, and radio observations of this system. During a pointed XMM observation ∼17 d after the eRASS5 detection, J1331 was not detected in the 0.2–2 keV band, constraining the 0.2–2 keV flux to have decayed by a factor of ≳40 over this period. Given the extremely low probability (∼5 × 10−6) of observing two independent full TDEs from the same galaxy over a 30 yr period, we consider the variability seen in J1331 to be likely caused by two partial TDEs involving a star on an elliptical orbit around a black hole. J1331-like flares show faster rise and decay time-scales $\mathcal {O}(\mathrm{d})$ compared to standard TDE candidates, with negligible ongoing accretion at late times post-disruption between outbursts.
BL Lacertae (BL Lac) objects are prominent members of the third Fermi Large Area Telescope catalog of γ-ray sources. Half of the members of the BL Lac population (∼300) lack redshift measurements, ...which is due to the absence of lines in their optical spectra, thereby making it difficult to utilize spectroscopic methods. Our photometric dropout technique can be used to establish the redshift for a fraction of these sources. This work employed six filters mounted on the Swift-UVOT and four optical filters on two telescopes, the 0.65 m SARA-CTIO in Chile and 1.0 m SARA-ORM in the Canary Islands, Spain. A sample of 15 sources was extracted from the Swift archival data for which six filter UVOT observations were conducted. By complementing the Swift observations with the SARA ones, we were able to discover two high-redshift sources: 3FGL J1155.4-3417 and 3FGL J1156.7-2250 at z = 1.83 − 0.13 + 0.10 and z = 1.73 − 0.19 + 0.11 , respectively, resulting from the dropouts in the power-law template fits to these data. The discoveries add to the important (26 total) sample of high-redshift BL Lacs. While the sample of high-z BL Lacs is still rather small, these objects do not seem to fit well within known schemes of the blazar population and represent the best probes of the extragalactic background light.
In this paper we provide experimental evidence on the relation of individual risk attitudes and subjects׳ aversion to favorable inequality. In a within-subjects design we expand Blanco et al.׳s ...(2011) modified dictator game by the risk-elicitation task of Eckel and Grossman (2002). Our data show strong support for a significant negative correlation between risk tolerance and an aversion to favorable inequality. The results are independent of gender, i.e., women and men show a similar correlation in these traits.
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