A predicted astrometric microlensing event by a nearby white dwarf

We used the Tycho-Gaia Astrometric Solution catalogue, part of the Gaia Data Release 1, to search for candidate astrometric microlensing events expected to occur within the remaining lifetime of the Gaia satellite. Our search yielded one promising candidate. We predict that the nearby DQ type white dwarf LAWD 37 (WD 1142-645) will lens a background star and will reach closest approach on November 11th 2019 ($\pm$ 4 days) with impact parameter $380\pm10$ mas. This will produce an apparent maximum deviation of the source position of $2.8\pm0.1$ mas. In the most propitious circumstance, Gaia will be able to determine the mass of LAWD 37 to $\sim3\%$. This mass determination will provide an independent check on atmospheric models of white dwarfs with helium rich atmospheres, as well as tests of white dwarf mass radius relationships and evolutionary theory

WISE J064336.71-022315.4: A Thick Disk L8 Gaia DR2-Discovered Brown Dwarf at 13.9 Parsecs

While spectroscopically characterizing nearby ultracool dwarfs discovered in the Gaia Second Data Release with the TripleSpec spectrograph on the Palomar 200'' telescope, we encountered a particularly cool, nearby, new member of the solar neighborhood: Gaia DR2 3106548406384807680 = WISE J064336.71-022315.4 = 2MASS J06433670-0223130. The $\it{Gaia}$ parallax corresponds to a distance of 13.9 $\pm$ 0.3 pc. Using our TripleSpec spectrum we classify W0643 as spectral type L8, and measured a heliocentric radial velocity of 142 $\pm$ 12 km s$^{-1}$. When combined with $\it{Gaia}$ astrometry, we determine a Galactic velocity (heliocentric; $U$ towards Galactic center) of $U, V, W$ = -109, -91, -12 ($\pm$10, 5, 3) km s$^{-1}$. We estimate that W0643 passed within $\sim$1.4 pc away from the Sun $\sim$100,000 years ago

The Temporal Singularity: time-accelerated simulated civilizations and their implications

Provided significant future progress in artificial intelligence and computing, it may ultimately be possible to create multiple Artificial General Intelligences (AGIs), and possibly entire societies living within simulated environments. In that case, it should be possible to improve the problem solving capabilities of the system by increasing the speed of the simulation. If a minimal simulation with sufficient capabilities is created, it might manage to increase its own speed by accelerating progress in science and technology, in a way similar to the Technological Singularity. This may ultimately lead to large simulated civilizations unfolding at extreme temporal speedups, achieving what from the outside would look like a Temporal Singularity. Here we discuss the feasibility of the minimal simulation and the potential advantages, dangers, and connection to the Fermi paradox of the Temporal Singularity. The medium-term importance of the topic derives from the amount of computational power required to start the process, which could be available within the next decades, making the Temporal Singularity theoretically possible before the end of the century.Comment: To appear in the conference proceedings of the AGI-18 conference (published in the Springer's Lecture Notes in AI series

Acute Cellular Alterations in the Hippocampus After Status Epilepticus

The critical, fundamental mechanisms that determine the emergence of status epilepticus from a single seizure and the prolonged duration of status epilepticus are uncertain. However, several general concepts of the pathophysiology of status epilepticus have emerged: (a) the hippocampus is consistently activated during status epilepticus; (b) loss of GABA-mediated inhibitory synaptic transmission in the hippocampus is critical for emergence of status epilepticus; and, finally (c) glutamatergic excitatory synaptic transmission is important in sustaining status epilepticus. This review focuses on the alteration of GABAergic inhibition in the hippocampus that occurs during the prolonged seizures of status epilepticus. If reduction in GABAergic inhibition leads to development of status epilepticus, enhancement of GABAergic inhibition would be expected to interrupt status epilepticus. Benzodiazepines and barbiturates are both used in the treatment of status epilepticus and both drugs enhance GABA A receptor-mediated inhibition. However, patients often become refractory to benzodiazepines when seizures are prolonged, and barbiturates are often then used for these refractory cases of status epilepticus. Recent evidence suggests the presence of multiple GABA A receptor isoforms in the hippocampus with different sensitivity to benzodiazepines but similar sensitivity to barbiturates, thus explaining why the two drug classes might have different clinical effects. In addition, rapid functional plasticity of GABA A receptors has been demonstrated to occur during status epilepticus in rats. During status epilepticus, there was a substantial reduction of diazepam potency for termination of the seizures. The loss of sensitivity of the animals to diazepam during status epilepticus was accompanied by an alteration in the functional properties of hippocampal dentate granule cell GABA A receptors. Dentate granule cell GABA A receptor currents from rats undergoing status epilepticus had reduced sensitivity to diazepam and zinc but normal sensitivity to GABA and pentobarbital. Therefore, the prolonged seizures of status epilepticus rapidly altered the functional properties of hippocampal dentate granule cell GABA A receptors, possibly explaining why benzodiazepines and barbiturates may not be equally effective during treatment of the prolonged seizures of status epilepticus. A comprehensive understanding of the cellular and molecular events leading to the development, maintenance, and cytotoxicity of status epilepticus should permit development of more effective treatment strategies and reduction in the mortality and morbidity of status epilepticus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65664/1/j.1528-1157.1999.tb00873.x.pd

Search for sterile neutrino mixing in the MINOS long-baseline experiment

A search for depletion of the combined flux of active neutrino species over a 735 km baseline is reported using neutral-current interaction data recorded by the MINOS detectors in the NuMI neutrino beam. Such a depletion is not expected according to conventional interpretations of neutrino oscillation data involving the three known neutrino flavors. A depletion would be a signature of oscillations or decay to postulated noninteracting sterile neutrinos, scenarios not ruled out by existing data. From an exposure of 3.18×1020 protons on target in which neutrinos of energies between ~500¿¿MeV and 120 GeV are produced predominantly as ¿µ, the visible energy spectrum of candidate neutral-current reactions in the MINOS far detector is reconstructed. Comparison of this spectrum to that inferred from a similarly selected near-detector sample shows that of the portion of the ¿µ flux observed to disappear in charged-current interaction data, the fraction that could be converting to a sterile state is less than 52% at 90% confidence level (C.L.). The hypothesis that active neutrinos mix with a single sterile neutrino via oscillations is tested by fitting the data to various models. In the particular four-neutrino models considered, the mixing angles ¿24 and ¿34 are constrained to be less than 11° and 56° at 90% C.L., respectively. The possibility that active neutrinos may decay to sterile neutrinos is also investigated. Pure neutrino decay without oscillations is ruled out at 5.4 standard deviations. For the scenario in which active neutrinos decay into sterile states concurrently with neutrino oscillations, a lower limit is established for the neutrino decay lifetime t3/m3>2.1×10-12¿¿s/eV at 90% C.L

First observations of separated atmospheric nu_mu and bar{nu-mu} events in the MINOS detector

The complete 5.4 kton MINOS far detector has been taking data since the beginning of August 2003 at a depth of 2070 meters water-equivalent in the Soudan mine, Minnesota. This paper presents the first MINOS observations of nuµ and [overline nu ]µ charged-current atmospheric neutrino interactions based on an exposure of 418 days. The ratio of upward- to downward-going events in the data is compared to the Monte Carlo expectation in the absence of neutrino oscillations, giving Rup/downdata/Rup/downMC=0.62-0.14+0.19(stat.)±0.02(sys.). An extended maximum likelihood analysis of the observed L/E distributions excludes the null hypothesis of no neutrino oscillations at the 98% confidence level. Using the curvature of the observed muons in the 1.3 T MINOS magnetic field nuµ and [overline nu ]µ interactions are separated. The ratio of [overline nu ]µ to nuµ events in the data is compared to the Monte Carlo expectation assuming neutrinos and antineutrinos oscillate in the same manner, giving R[overline nu ][sub mu]/nu[sub mu]data/R[overline nu ][sub mu]/nu[sub mu]MC=0.96-0.27+0.38(stat.)±0.15(sys.), where the errors are the statistical and systematic uncertainties. Although the statistics are limited, this is the first direct observation of atmospheric neutrino interactions separately for nuµ and [overline nu ]µ

Efficient Evaluation of Low Degree Multivariate Polynomials in Ring-LWE Homomorphic Encryption Schemes

Homomorphic encryption schemes allow to perform computations over encrypted data. In schemes based on RLWE assumption the plaintext data is a ring polynomial. In many use cases of homomorphic encryption only the degree-0 coefficient of this polynomial is used to encrypt data. In this context any computation on encrypted data can be performed. It is trickier to perform generic computations when more than one coefficient per ciphertext is used. In this paper we introduce a method to efficiently evaluate low-degree multivariate polynomials over encrypted data. The main idea is to encode several messages in the coefficients of a plaintext space polynomial. Using ring homomorphism operations and multiplications between ciphertexts, we compute multivariate monomials up to a given degree. Afterwards, using ciphertext additions we evaluate the input multivariate polynomial. We perform extensive experimentations of the proposed evaluation method. As example, evaluating an arbitrary multivariate degree-3 polynomial with 100 variables over Boolean space takes under 13 seconds

Protocol for the immediate delivery versus expectant care of women with preterm prelabour rupture of the membranes close to term (PPROMT) Trial [ISRCTN44485060]

BACKGROUND: Preterm prelabour rupture of membranes (PPROM) complicates up to 2% of all pregnancies and is the cause of 40% of all preterm births. The optimal management of women with PPROM prior to 37 weeks, is not known. Furthermore, diversity in current clinical practice suggests uncertainty about the appropriate clinical management. There are two options for managing PPROM, expectant management (a wait and see approach) or early planned birth. Infection is the main risk for women in which management is expectant. This risk need to be balanced against the risk of iatrogenic prematurity if early delivery is planned. The different treatment options may also have different health care costs. Expectant management results in prolonged antenatal hospitalisation while planned early delivery may necessitate intensive care of the neonate for problems associated with prematurity. METHODS/DESIGN: We aim to evaluate the effectiveness of early planned birth compared with expectant management for women with PPROM between 34 weeks and 36(6 )weeks gestation, in a randomised controlled trial. A secondary aim is a cost analysis to establish the economic impact of the two treatment options and establish the treatment preferences of women with PPROM close to term. The early planned birth group will be delivered within 24 hours according to local management protocols. In the expectant management group birth will occur after spontaneous labour, at term or when the attending clinician feels that birth is indicated according to usual care. Approximately 1812 women with PPROM at 34–36(6 )weeks gestation will be recruited for the trial. The primary outcome of the study is neonatal sepsis. Secondary infant outcomes include respiratory distress, perinatal mortality, neonatal intensive care unit admission, assisted ventilation and early infant development. Secondary maternal outcomes include chorioamnionitis, postpartum infection treated with antibiotics, antepartum haemorrhage, induction of labour, mode of delivery, maternal satisfaction with care, duration of hospitalisation, and maternal wellbeing at four months postpartum. DISCUSSION: This trial will provide evidence on the optimal care for women with PPROM close to term (34–37 weeks gestation). Consideration of both the clinical and economic sequelae of the management of PPROM will enable informed decision making and guideline development

Underground Wireless Channel Bandwidth and Capacity

The UG channel bandwidth and capacity are vital parameters in wireless underground communication system design. In this chapter, a comprehensive analysis of the wireless underground channel capacity is presented. The impact of soil on return loss, bandwidth, and path loss is discussed. The results of underground multi-carrier modulation capacity are also outlined. Moreover, the single user capacity and multi-carrier capacity are also introduced with an in-depth treatment of soil texture, soil moisture, and distance effects on channel capacity. Finally, the chapter is concluded with a discussion of challenges and open research issues