Probing millisecond pulsar emission geometry using light curves from the Fermi Large Area Telescope

An interesting new high-energy pulsar sub-population is emerging following early discoveries of gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope (LAT). We present results from 3D emission modeling, including the Special Relativistic effects of aberration and time-of-flight delays and also rotational sweepback of B-field lines, in the geometric context of polar cap (PC), outer gap (OG), and two-pole caustic (TPC) pulsar models. In contrast to the general belief that these very old, rapidly-rotating neutron stars (NSs) should have largely pair-starved magnetospheres due to the absence of significant pair production, we find that most of the light curves are best fit by TPC and OG models, which indicates the presence of narrow accelerating gaps limited by robust pair production -- even in these pulsars with very low spin-down luminosities. The gamma-ray pulse shapes and relative phase lags with respect to the radio pulses point to high-altitude emission being dominant for all geometries. We also find exclusive differentiation of the current gamma-ray MSP population into two MSP sub-classes: light curve shapes and lags across wavebands impose either pair-starved PC (PSPC) or TPC / OG-type geometries. In the first case, the radio pulse has a small lag with respect to the single gamma-ray pulse, while the (first) gamma-ray peak usually trails the radio by a large phase offset in the latter case. Finally, we find that the flux correction factor as a function of magnetic inclination and observer angles is typically of order unity for all models. Our calculation of light curves and flux correction factor for the case of MSPs is therefore complementary to the "ATLAS paper" of Watters et al. for younger pulsars.Comment: 51 pages, 23 figures, 3 tables; low-resolution figures; accepted for publication by Ap

Hardy's Inequality for the fractional powers of Grushin operator

We prove Hardy's inequality for the fractional powers of the generalized sublaplacian and the fractional powers of the Grushin operator. We also find an integral representation and a ground state representation for the fractional powers of generalized sublaplacian

Should HIV be a notifiable disease? Old questions with some new arguments

KMHIV notification enters national debate regularly, often introduced by politicians and supported by many individual healthcare workers. We argue that its proponents advance confused or poorly informed rationales for making HIV notifiable. We present reasons why making HIV notifiable would be inappropriate in South Africa, why the public health benefits of a notification programme are not even likely, and why there are risks of public health and human rights harms

Degradation and forgone removals increase the carbon impact of intact forest loss by 626%

Intact tropical forests, free from substantial anthropogenic influence, store and sequester large amounts of atmospheric carbon but are currently neglected in international climate policy. We show that between 2000 and 2013, direct clearance of intact tropical forest areas accounted for 3.2% of gross carbon emissions from all deforestation across the pantropics. However, full carbon accounting requires the consideration of forgone carbon sequestration, selective logging, edge effects, and defaunation. When these factors were considered, the net carbon impact resulting from intact tropical forest loss between 2000 and 2013 increased by a factor of 6 (626%), from 0.34 (0.37 to 0.21) to 2.12 (2.85 to 1.00) petagrams of carbon (equivalent to approximately 2 years of global land use change emissions). The climate mitigation value of conserving the 549 million ha of tropical forest that remains intact is therefore significant but will soon dwindle if their rate of loss continues to accelerate

Histamine stimulates the proliferation of small and large cholangiocytes by activation of both IP3/Ca2+ and cAMP-dependent signaling mechanisms

Although large cholangiocytes exert their functions by activation of cyclic adenosine 3',5'-monophosphate (cAMP), Ca(2+)-dependent signaling regulates the function of small cholangiocytes. Histamine interacts with four receptors, H1-H4HRs. H1HR acts by Gαq activating IP(3)/Ca(2+), whereas H2HR activates Gα(s) stimulating cAMP. We hypothesize that histamine increases biliary growth by activating H1HR on small and H2HR on large cholangiocytes. The expression of H1-H4HRs was evaluated in liver sections, isolated and cultured (normal rat intrahepatic cholangiocyte culture (NRIC)) cholangiocytes. In vivo, normal rats were treated with histamine or H1-H4HR agonists for 1 week. We evaluated: (1) intrahepatic bile duct mass (IBDM); (2) the effects of histamine, H1HR or H2HR agonists on NRIC proliferation, IP(3) and cAMP levels and PKCα and protein kinase A (PKA) phosphorylation; and (3) PKCα silencing on H1HR-stimulated NRIC proliferation. Small and large cholangiocytes express H1-H4HRs. Histamine and the H1HR agonist increased small IBDM, whereas histamine and the H2HR agonist increased large IBDM. H1HR agonists stimulated IP(3) levels, as well as PKCα phosphorylation and NRIC proliferation, whereas H2HR agonists increased cAMP levels, as well as PKA phosphorylation and NRIC proliferation. The H1HR agonist did not increase proliferation in PKCα siRNA-transfected NRICs. The activation of differential signaling mechanisms targeting small and large cholangiocytes is important for repopulation of the biliary epithelium during pathologies affecting different-sized bile ducts