Originally published in 1933. As mediaeval society was dominated by the feudal caste, a biography that depicts the position, activities, manners, and thoughts of a member of that class might do much ...to elucidate the history of the period. This is what Sidney Painter had in mind when he wrote a William Marshal: Knight-Errant, Baron, and Regent of England. The subject has proved a peculiarly fortunate one. The fourth son of John fitz Gilbert, marshal of the king's court, William for the first forty years of his life was a landless knight who devoted most of his time and energy to tournaments. In the year 1189 by his marriage to the daughter and heiress of Earl Richard of Pembroke, William became a great feudal lord with fiefs in Normandy, England, Wales, and Ireland. Thus his biography depicts the two extremes of feudal society—the landless knight and the rich baron. Finally in 1216 he was chosen regent of England for the young king, Henry III, and his biography becomes for three years the history of England.
ABSTRACT
We present optical time-resolved multiband photometry of the black widow binary millisecond pulsar J2052+1219 using direct-imaging observations with the 2.1-m telescope of the Observatorio ...Astronomico Nacional San Pedro Mártir (OAN-SPM), Mexico. The observations reveal a variable optical source whose position and periodicity, P = 2.752 h, coincide with the pulsar coordinates and the orbital period obtained from radio timing. This has allowed us to identify it with its binary companion. We reproduce the light curves of the source, modelling the companion’s heating by the pulsar and accounting for the system parameters obtained from the radio data. As a result, we estimate the distance to the system independently as 3.94(16) kpc, which agrees with the dispersion measure distance. The size of the companion star is 0.12−0.15 R$\odot$, close to filling its Roche lobe. It has a surface temperature difference of about 3000 K between the side facing the pulsar and the back side. We summarize characteristics of all black widow systems studied in the optical and we compare them with the parameters of PSR J2052+1219 derived from our observations.
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•D3R regulates DAT in a biphasic way.•Acute D3R activation increases DAT expression in the plasma membrane and DA uptake.•Prolonged D3R activation promotes DAT phosphorylation and ...ubiquitination.•After prolonged D3R activation, DAT is degraded, reducing DA uptake.
The dopamine transporter (DAT) is a membrane glycoprotein in dopaminergic neurons, which modulates extracellular and intracellular dopamine levels. DAT is regulated by different presynaptic proteins, including dopamine D2 (D2R) and D3 (D3R) receptors. While D2R signalling enhances DAT activity, some data suggest that D3R has a biphasic effect. However, despite the extensive therapeutic use of D2R/D3R agonists in neuropsychiatric disorders, this phenomenon has been little studied. In order to shed light on this issue, DAT activity, expression and posttranslational modifications were studied in mice and DAT-D3R-transfected HEK cells. Consistent with previous reports, acute treatment with D2R/D3R agonists promoted DAT recruitment to the plasma membrane and an increase in DA uptake. However, when the treatment was prolonged, DA uptake and total striatal DAT protein declined below basal levels. These effects were inhibited in mice by genetic and pharmacological inactivation of D3R, but not D2R, indicating that they are D3R-dependent. No changes were detected in mesostriatal tyrosine hydroxylase (TH) protein expression and midbrain TH and DAT mRNAs, suggesting that the dopaminergic system is intact and DAT is posttranslationally regulated. The use of immunoprecipitation and cell surface biotinylation revealed that DAT is phosphorylated at serine residues, ubiquitinated and released into late endosomes through a PKCβ-dependent mechanism. In sum, the results indicate that long-term D3R activation promotes DAT down-regulation, an effect that may underlie neuroprotective and antidepressant actions described for some D2R/D3R agonists.
We present the results from 1.5 and 5 GHz phase-referenced VLBA and 1.5 GHz Karl G. Jansky Very Large Array (VLA) observations of the Seyfert 2 galaxy KISSR 1219, which exhibits double-peaked ...emission lines in its optical spectrum. The VLA and VLBA data reveal a one-sided core-jet structure at roughly the same position angles, providing evidence of an active galactic nucleus outflow. The absence of dual parsec-scale radio cores puts the binary black-hole picture in doubt for the case of KISSR 1219. The high brightness temperatures of the parsec-scale core and jet components (>106 K) are consistent with this interpretation. Doppler boosting with jet speeds of 0.55c to 0.25c, going from parsec to kiloparsec scales, at a jet inclination 50° can explain the jet one-sidedness in this Seyfert 2 galaxy. A blueshifted broad emission line component in O iii is also indicative of an outflow in the emission line gas at a velocity of ∼350 km s−1, while the O i doublet lines suggest the presence of shock-heated gas. A detailed line ratio study using the MAPPINGS III code further suggests that a shock+precursor model can explain the line ionization data well. Overall, our data suggest that the radio outflow in KISSR 1219 is pushing the emission line clouds, both ahead of the jet and in a lateral direction, giving rise to the double peak emission line spectra.
The past decade is known as the era of integrations where multiple technologies had integrated, and new research trends were seen. The security of data and information in the digital world has been a ...challenge to everyone; Blockchain technology has attracted many researchers in these scenarios. This paper focuses on finding the current trends in Blockchain technology to help the researchers select an area to carry future research. The data related to Blockchain Technologies have been collected from IEEE, Springer, ACM, and other digital databases. Then, the formulated corpus is used for topic modelling, and Latent Dirichlet Allocation is deployed. The outcomes of the Latent Dirichlet Allocation model are then analyzed based on various extracted key terms and key documents found for each topic. All the topic solution has been identified from the bag of words. The extracted topics are thereafter semantically mapped. Thus, based on the analysis of more than 900 papers, the most recent research trends have been discussed in this paper, ultimately focusing on the areas that need more attention from the research community. Also, the meta data analysis has been accomplished, evaluating the year wise and publication source wise research growth. More than 15 research directions are elaborated in this paper, which can direct and guide the researchers to pursuit the research in specific trends and also, find the research gaps in various technologies associated with Blockchain Technology.
The sulfur isotope ratio (δ34S) recorded in marine barite is commonly used to estimate secular changes in the sulfur isotopic composition of seawater sulfate (δ34SSO4) throughout Earth's history. The ...Cenozoic record demonstrates a drastic 5‰ increase in seawater δ34SSO4 during the Early Eocene. However, the gradient of this excursion is based on only a few data points. Taking advantage of a much improved biostratigraphic framework, we redefine the Eocene δ34SSO4 data with a new high-resolution barite based δ34S record between 60 and 30 Ma. Our results show that the rise of δ34SSO4 starts about 3 million years later (~53 Ma) and lasts about 9 million years longer (until 38 Ma) than previously depicted. As such, the gradient of the δ34S curve is ~0.4‰/Myr. The radiogenic strontium isotopic ratio in barite suggests that some of the samples used for the original barite record are affected by diagenetic alteration.
•Significantly improved data density for the most prominent feature of the Cenozoic marine S-isotope record, the 5‰ rise during the Eocene.•The duration of the S-isotope rise increases from 9 to 15 million years (38-53 vs. 47-56 Ma).•S and Sr isotope ratios recorded in barite are sensitive to cryptic diagenesis that is not detectable by SEM imaging.•Marine barite and CAS data track each other with astounding fidelity, recording the actual seawater S-isotope ratio.
The oceanic magnesium cycle is largely controlled by continental weathering and marine authigenic mineral formation, which are intimately linked to long-term climate. Uncertainties in the magnesium ...cycle propagate into other chemical budgets, and into interpretations of paleo-oceanographic reconstructions of seawater δ
Mg and Mg/Ca ratios. Here, we produce a detailed global map of the flux of dissolved magnesium from the ocean into deeper marine sediments (greater than ∼1 meter below seafloor), and quantify the global flux and associated isotopic fractionation. We find that this flux accounts for 15-20% of the output of magnesium from the ocean, with a flux-weighted fractionation factor of ∼0.9994 acting to increase the magnesium isotopic ratio in the ocean. Our analysis provides the best constraints to date on the sources and sinks that define the oceanic magnesium cycle, including new constraints on the output flux of magnesium and isotopic fractionation during low-temperature ridge flank hydrothermal circulation.
Magnesium concentrations in deep-sea sediment pore-fluids typically decrease down core due to net precipitation of dolomite or clay minerals in the sediments or underlying crust. To better ...characterize and differentiate these processes, we have measured magnesium isotopes in pore-fluids and sediment samples from Ocean Drilling Program sites (1082, 1086, 1012, 984, 1219, and 925) that span a range of oceanographic settings. At all sites, magnesium concentrations decrease with depth. At sites where diagenetic reactions are dominated by the respiration of organic carbon, pore-fluid δ
26Mg values increase with depth by as much as 2‰. Because carbonates preferentially incorporate
24Mg (low δ
26Mg), the increase in pore-fluid δ
26Mg values at these sites is consistent with the removal of magnesium in Mg-carbonate (dolomite). In contrast, at sites where the respiration of organic carbon is not important and/or weatherable minerals are abundant, pore-fluid δ
26Mg values decrease with depth by up to 2‰. The decline in pore-fluid δ
26Mg at these sites is consistent with a magnesium sink that is isotopically enriched relative to the pore-fluid. The identity of this enriched magnesium sink is likely clay minerals. Using a simple 1D diffusion–advection–reaction model of pore-fluid magnesium, we estimate rates of net magnesium uptake/removal and associated net magnesium isotope fractionation factors for sources and sinks at all sites. Independent estimates of magnesium isotope fractionation during dolomite precipitation from measured δ
26Mg values of dolomite samples from sites 1082 and 1012 are very similar to modeled net fractionation factors at these sites, suggesting that local exchange of magnesium between sediment and pore-fluid at these sites can be neglected. Our results indicate that the magnesium incorporated in dolomite is 2.0–2.7‰ depleted in δ
26Mg relative to the precipitating fluid. Assuming local exchange of magnesium is minor at the rest of the studied sites, our results suggest that magnesium incorporated into clay minerals is enriched in δ
26Mg by 0‰ to +1.25‰ relative to the precipitating fluid. This work demonstrates the utility of magnesium isotopes as a tracer for magnesium sources/sinks in low-temperature aqueous systems.
•Sulfate δ34S and δ18OSO4 decline at the emergent icehouse conditions during the EOT.•Loss of submerged shelves transfers S from sedimentary pyrite to dissolved sulfate.•Lowstand-induced pyrite ...oxidation generates sulfuric acid and dissolves carbonates.•Pyrite oxidation can raise pCO2, providing stabilizing feedback to ice-sheet growth.
The Eocene-Oligocene transition (EOT) is characterized by a global cooling trend, falling sea levels, and the onset of Antarctic glaciation. Previous studies investigate the interactions and feedbacks between ocean circulation, weathering, and atmospheric CO2 levels during this time. Here we explore the role of biogeochemical sulfur cycling, and report seawater sulfate isotope data across the EOT. Our data show that seawater sulfate δ34S and δ18OSO4 values decline by 0.6‰ and 1.5‰, respectively, between 34.5 and 33 Ma. Quantitative modeling suggests that approximately 8,000 Gt of the sulfide previously stored in shelf sediments has been reoxidized and transferred to the marine sulfate pool. This reoxidation process proceeds through reactions similar to those associated with acid mine drainage, generating 24,500 Gt sulfuric acid. These numbers are of similar magnitude as those estimated for Pleistocene glaciations and must have affected marine pH and/or alkalinity.
The RSA cryptosystem comprises of two important features that are needed for encryption process known as the public parameter
e
and the modulus
N
. In 1999, a cryptanalysis on RSA which was described ...by Boneh and Durfee focused on the key equation
e
d
-
k
ϕ
(
N
)
=
1
and
e
of the same magnitude to
N
. Their method was applicable for the case of
d
<
N
0.292
via Coppersmith’s technique. In 2012, Kumar et al. presented an improved Boneh-Durfee attack using the same equation which is valid for any e with arbitrary size. In this paper, we present an exponential increment of the two former attacks using the variant equation
e
a
-
ϕ
(
N
)
b
=
c
. The new attack breaks the RSA system when
a
and |
c
| are suitably small integers. Moreover, the new attack shows that the Boneh-Durfee attack and the attack of Kumar et al. can be derived using a single attack. We also showed that our bound manage to improve the bounds of Ariffin et al. and Bunder and Tonien.
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