There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

On August 17, 2017 at 12∶41:04 UTC the Advanced LIGO and Advanced Virgo gravitational-wave detectors made their first observation of a binary neutron star inspiral. The signal, GW170817, was detected with a combined signal-to-noise ratio of 32.4 and a false-alarm-rate estimate of less than one per 8.0×10^{4}  years. We infer the component masses of the binary to be between 0.86 and 2.26  M_{⊙}, in agreement with masses of known neutron stars. Restricting the component spins to the range inferred in binary neutron stars, we find the component masses to be in the range 1.17-1.60  M_{⊙}, with the total mass of the system 2.74_{-0.01}^{+0.04}M_{⊙}. The source was localized within a sky region of 28  deg^{2} (90% probability) and had a luminosity distance of 40_{-14}^{+8}  Mpc, the closest and most precisely localized gravitational-wave signal yet. The association with the γ-ray burst GRB 170817A, detected by Fermi-GBM 1.7 s after the coalescence, corroborates the hypothesis of a neutron star merger and provides the first direct evidence of a link between these mergers and short γ-ray bursts. Subsequent identification of transient counterparts across the electromagnetic spectrum in the same location further supports the interpretation of this event as a neutron star merger. This unprecedented joint gravitational and electromagnetic observation provides insight into astrophysics, dense matter, gravitation, and cosmology.

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GW170817: observation of gravitational waves from a binary neutron star inspiral

Hepatocellular Carcinoma: Epidemiology and Molecular Carcinogenesis

With approximately $50$ binary black hole events detected by LIGO/Virgo to date and many more expected in the next few years, gravitational-wave astronomy is shifting from individual-event analyses to population studies aimed at understanding the formation scenarios of these sources. There is strong evidence that the black hole mergers detected so far belong to multiple formation channels. We perform a hierarchical Bayesian analysis on the GWTC-2 catalog using a combination of ab-initio astrophysical formation models (including common envelope, globular clusters, and nuclear star clusters) as well as a realistic population of primordial black holes formed in the early universe. The evidence for a primordial population is decisively favored compared to the null hypothesis and the inferred fraction of primordial black holes in the current data is estimated at $0.27^{+0.28}_{-0.24}$ ($90\%$ credible interval), a figure which is robust against different assumptions on the astrophysical populations. The primordial formation channel can explain events in the upper mass gap such as GW190521, which are in tension with astrophysical formation scenarios. Our results suggest the tantalizing possibility that LIGO/Virgo may have already detected black holes formed after inflation. This conclusion can ultimately be confirmed in the era of third-generation interferometers.

Evidence for primordial black holes in LIGO/Virgo gravitational-wave data

The present study was designed to determine whether a delay in the start of the promoting regimen after the administration of a carcinogen would influence the promoting efficacy of orotic acid on the development of hepatocellular carcinoma in rats. Male Fischer 344 rats weighing 130-150 g were injected with a single dose of diethylnitrosamine (200 mg/kg body wt i.p.) then divided into 3 groups: groups 1 and 2 were given semi-synthetic basal diet or the same diet containing 1% orotic acid (OA) respectively starting 1 week after the carcinogen; group 3 received the OA diet starting 5 weeks after the administration of diethylnitrosamine. Animals from these 3 groups were sacrificed after 25, 32, 42 and 60 weeks of being fed their respective diets. The results indicated that delaying the start of the OA diet after the carcinogen resulted in about a 50% decrease in the incidence of hepatic nodules and/or hepatocellular carcinomas at various time points during the experiment. This decrease in promoting efficacy of OA was not apparently explainable by lack of metabolic effects of OA, at least in terms of induction of nucleotide pool imbalance, a condition that appears to be important for OA to exert its tumor promoting effects.

Increasing the interval between initiation and the onset of exposure to orotic acid decreases its promoting effect on rat liver carcinogenesis.

We construct exact, time-dependent, black hole solutions of Einstein-Maxwell-dilaton theory with arbitrary dilaton coupling, a. For a=1 this theory arises as the four-dimensional low-energy effective description of heterotic string theory. These solutions represent electrically charged, spherically symmetric black holes emitting or absorbing charged null dust and generalize the Vaidya and Bonnor-Vaidya solutions of general relativity and of Einstein-Maxwell theory, respectively. The a=1 case stands out as special, in the sense that it is the only choice of the coupling that allows for a time-dependent dilaton field in this class of solutions. As a by-product, we prove that an electrically charged black hole in this theory cannot be overcharged by bombarding it with a stream of electrically charged null dust. This provides an example of cosmic censorship observance in a string theory setting.

Radiating black holes in Einstein-Maxwell-dilaton theory

Gravitational-wave (GW) detections of binary neutron star coalescences play a crucial role to constrain the microscopic interaction of matter at ultrahigh density. Similarly, if boson stars exist in the universe their coalescence can be used to constrain the fundamental coupling constants of a scalar field theory. We develop the first coherent waveform model for the inspiral of boson stars with quartic interactions. The waveform includes coherently spin-induced quadrupolar and tidal-deformability contributions in terms of the masses and spins of the binary and of a single coupling constant of the theory. We show that future instruments such as the Einstein Telescope and LISA can provide strong, complementary bounds on bosonic self-interactions, while the constraining power of current detectors is marginal.

Paolo Pani

Papers

Evidence for primordial black holes in LIGO/Virgo gravitational-wave data

Increasing the interval between initiation and the onset of exposure to orotic acid decreases its promoting effect on rat liver carcinogenesis.

Radiating black holes in Einstein-Maxwell-dilaton theory

Gravitational-wave detectors as particle-physics laboratories: Constraining scalar interactions with boson-star binaries

The observational evidence for horizons: from echoes to precision GW physics