5,659 research outputs found
The observational evidence pertinent to possible kick mechanisms in neutron stars
We examine available observations on pulsars for evidence pertaining to
mechanisms proposed to explain the origin of their velocities. We find that
mechanisms predicting a correlation between the rotation axis and the pulsar
velocity are ruled out. Also, that there is no significant correlation between
pulsar magnetic field strengths and velocities. With respect to recent
suggestions postulating asymmetric impulses at birth being solely responsible
for both the spins and velocities of pulsars, single impulses of any duration
and multiple extended duration impulses appear ruled out.Comment: 7 pages. Accepted for publication in Astronomy & Astrophysic
D0 Dimuon Asymmetry in Mixing and Constraints on New Physics
We study the consequences of the large dimuon asymmetry observed at D0.
Physics beyond the standard model (SM) in mixing is required to
explain the data. We first present a detailed analysis for model independent
constraints on physics beyond the SM, and then study the implications for
theoretical models which modify the SM results in different ways, such as
with FCNC and R-parity violating SUSY contributions.Comment: RevTex 13 pages, 6 figures. References added. Modified some
discussions. Version to appear in PR
Safety Instrumented Bypass Management
PresentationProper management of Safety Instrumented Function (SIF) bypasses during process plant operation can be challenging and could compromise process safety if the SIF is bypassed longer than its allowable maximum time interval. Safety bypass procedures are usually written on site to comply with OSHA 1910.119 and IEC61511. However, in practice, safety bypass management can be difficult due to a lack of readily available process safety information, lack of operator awareness and the existence of a production throughput oriented culture. For many operating sites, process safety information (PSI) is only available in Process Hazard Analysis (PHA) reports. Commercial databases are available which display process safety information and make it readily available to operations and maintenance to properly implement and handle safety bypasses. An alternative approach is the creation of an in-house process safety database to provide easily-accessed process safety information. This paper will present a case-study on how TOTAL-Port Arthur Refinery developed and implemented such a system. The paper will include our flow chart for bypass approval, how we perform a bypass risk assessment and how we developed our SIS database. This SIS database has also proven useful for ‘operator training’ on the risks associated with the process unit and the available safeguards to manage those risks
Vela, its X-ray nebula, and the polarization of pulsar radiation
The recent identification of the perpendicular mode of radio polarization as
the primary one in the Vela pulsar by Lai et al. (2001) is interpreted in terms
of the maser mechanism proposed by Luo & Melrose (1995). We suggest that such a
mechanism may also be operative for the parallel mode which opens up the
possibility of accounting for all types of polarization observed in pulsars. We
propose an alternative interpretation of the arcs in the nebular X-radiation
observed by Pavlov et al.(2000) & Helfand et al. (2001) with the Chandra
Observatory, and interpreted by the latter as an equatorial wind. We interpret
the arcs as traces of the particle beams from the two magnetic poles at the
shock front. We also propose that the alignment with the rotation axis of the
jet-like feature bisecting the arcs is an effect of projection on the sky plane
and that there is no physical jet along the axis of rotation.Comment: 7 pages, 3 figures; version 2; accepted for publication in A&
A Separate Higgs?
We investigate the possibility of a multi-Higgs doublet model where the
lightest neutral Higgs boson () decouples from the fermion sector. We are
partially motivated by the four events with
\,GeV recently observed by the L3 collaboration,
which could be a signal for .
Collider signatures for the additional physical Higgs bosons present in such
models are discussed.Comment: 8 pages (plus 2 figures, available by request), latex,
ANL-HEP-PR-92-10
Bitter Taste Receptors for Asthma Therapeutics.
Clinical management of asthma and chronic obstructive pulmonary disease (COPD) has primarily relied on the use of beta 2 adrenergic receptor agonists (bronchodilators) and corticosteroids, and more recently, monoclonal antibody therapies (biologics) targeting specific cytokines and their functions. Although these approaches provide relief from exacerbations, questions remain on their long-term efficacy and safety. Furthermore, current therapeutics do not address progressive airway remodeling (AR), a key pathological feature of severe obstructive lung disease. Strikingly, agonists of the bitter taste receptors (TAS2Rs) deliver robust bronchodilation, curtail allergen-induced inflammatory responses in the airways and regulate airway smooth muscle (ASM) cell proliferation and mitigate features of A
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