2,026,178 research outputs found
Factors Affecting The Intensity of Solar Energetic Particle Events
This paper updates the influence of environmental and source factors of
shocks driven by coronal mass ejections (CMEs) that are likely to influence the
solar energetic particle (SEP) events. The intensity variation due to CME
interaction reported in [1] is confirmed by expanding the investigation to all
the large SEP events of solar cycle 23. The large SEP events are separated into
two groups, one associated with CMEs running into other CMEs, and the other
with CMEs running into the ambient solar wind. SEP events with CME interaction
generally have a higher intensity. New possibilities such as the influence of
coronal holes on the SEP intensity are also discussed. For example, the
presence of a large coronal hole between a well-connected eruption and the
solar disk center may render the shock poorly connected because of the
interaction between the CME and the coronal hole. This point is illustrated
using the 2004 December 3 SEP event delayed by about 12 hours from the onset of
the associated CME. There is no other event at the Sun that can be associated
with the SEP onset. This event is consistent with the possibility that the
coronal hole interaction influences the connectivity of the CMEs that produce
SEPs, and hence the intensity of the SEP event.Comment: 6 pages, 2 figures, 2 table
The dynamics of eruptive prominences
This chapter discusses the dynamical properties of eruptive prominences in
relation to coronal mass ejections (CMEs). The fact that eruptive prominences
are a part of CMEs is emphasized in terms of their physical association and
kinematics. The continued propagation of prominence material into the
heliosphere is illustrated using in-situ observations. The solar-cycle
variation of eruptive prominence locations is discussed with a particular
emphasis on the rush-to-the-pole (RTTP) phenomenon. One of the consequences of
the RTTP phenomenon is polar CMEs, which are shown to be similar to the
low-latitude CMEs. This similarity is important because it provides important
clues to the mechanism by which CMEs erupt. The nonradial motion of CMEs is
discussed, including the deflection by coronal holes that have important space
weather consequences. Finally, the implications of the presented observations
for the modeling CME modeling are outlined.Comment: 28 pages, 15 figures, Chapter 15 of the book Solar Prominences,
edited by J.-C. Vial & O. Engvold, Springer, in press (2014
Metalinguistic Proposals
This paper sets out the felicity conditions for metalinguistic proposals, a type of directive illocutionary act. It discusses the relevance of metalinguistic proposals and other metalinguistic directives for understanding both small- and large-scale linguistic engineering projects, essentially contested concepts, metalinguistic provocations, and the methodology of ordinary language philosophy. Metalinguistic proposals are compared with other types of linguistic interventions, including metalinguistic negotiation, conceptual engineering, lexical warfare, and ameliorative projects
Solar Activity Studies using Microwave Imaging Observations
We report on the status of solar cycle 24 based on polar prominence eruptions
(PEs) and microwave brightness enhancement (MBE) information obtained by the
Nobeyama radioheliograph. The north polar region of the Sun had near-zero field
strength for more than three years (2012 to 2015) and ended only in September
2015 as indicated by the presence of polar PEs and the lack of MBE. The
zero-polar-field condition in the south started only around 2013, but it ended
by June 2014. Thus the asymmetry in the times of polarity reversal switched
between cycle 23 and 24. The polar MBE is a good proxy for the polar magnetic
field strength as indicated by the high degree of correlation between the two.
The cross-correlation between the high- and low-latitude MBEs is significant
for a lag of ~5.5 to 7.3 years, suggesting that the polar field of one cycle
indicates the sunspot number of the next cycle in agreement with the
Babcock-Leighton mechanism of solar cycles. The extended period of near-zero
field in the north-polar region should result in a weak and delayed sunspot
activity in the northern hemisphere in cycle 25.Comment: 4 pages, 6 figures, invited paper to the URSI Asia-Pacific Radio
Science Conference in Seoul, August 21-25, 201
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Predictors for Nonaccidental Trauma in a Child With a Fracture-A National Inpatient Database Study.
BackgroundDespite heightened awareness and multidisciplinary efforts, a predictive model to help the clinician quantify the likelihood of nonaccidental trauma (NAT) in a child presenting with a fracture does not exist. The purpose of this study was to develop an evidence-based likelihood of NAT in a child presenting with a fracture.MethodsUsing the 2012 Kids' Inpatient Database, we identified all available pediatric inpatients admitted with an extremity or spine fracture. Children with a fracture were subcategorized based on the diagnosis of NAT. Multivariate analysis using multiple logistic regression was used to generate odds ratios and create a predictive model for the probability of NAT in a child with a fracture.ResultsOf the 57,183 pediatric fracture cases, 881 (1.54%) had a concurrent diagnosis of NAT. Of these children, those presenting with multiple fractures had the highest rate of NAT (2.8%). The overall mortality rate in patients presenting with fractures and abuse was 1.8%, which was twice as high as patients without abuse (odds ratio [OR] = 2.0). Based on multivariate analysis, younger age (OR = 0.5), black race (OR = 1.7), intracranial injury (OR = 3.7), concomitant rib fracture (OR = 7.2), and burns (OR = 8.3) were positive predictors of NAT in a child with a fracture. A weighted equation using regression coefficients was generated and plotted on a receiver operative characteristic curve, demonstrating excellent correlation and probability of NAT (area under curve = 0.962). (Equation - ln (P/(1 - P)) = -1.79 - 0.65 (age in years) + 0.51 (black race) + 1.97 (rib fracture) + 1.31 (intracranial injury) + 2.12 (burn)).ConclusionUsing a large, national inpatient database, we identified an overall prevalence of 1.54% of NAT in children admitted to the hospital with a fracture. Based on five independent predictors of NAT, we generated an estimated probability chart that can be used in the clinical workup of a child with a fracture and possible NAT. This evidence-based algorithm needs to be validated in clinical practice.Level of evidencePrognostic study, Level III (case-control study)
Piperidinols that show anti-tubercular activity as inhibitors of arylamine N-acetyltransferase: an essential enzyme for mycobacterial survival inside macrophages
Latent M. tuberculosis infection presents one of the major obstacles in the global eradication of tuberculosis (TB). Cholesterol plays a critical role in the persistence of M. tuberculosis within the macrophage during latent infection. Catabolism of cholesterol contributes to the pool of propionyl-CoA, a precursor that is incorporated into cell-wall lipids. Arylamine N-acetyltransferase (NAT) is encoded within a gene cluster that is involved in the cholesterol sterol-ring degradation and is essential for intracellular survival. The ability of the NAT from M. tuberculosis (TBNAT) to utilise propionyl-CoA links it to the cholesterol-catabolism pathway. Deleting the nat gene or inhibiting the NAT enzyme prevents intracellular survival and results in depletion of cell-wall lipids. TBNAT has been investigated as a potential target for TB therapies. From a previous high-throughput screen, 3-benzoyl-4-phenyl-1-methylpiperidinol was identified as a selective inhibitor of prokaryotic NAT that exhibited antimycobacterial activity. The compound resulted in time-dependent irreversible inhibition of the NAT activity when tested against NAT from M. marinum (MMNAT). To further evaluate the antimycobacterial activity and the NAT inhibition of this compound, four piperidinol analogues were tested. All five compounds exert potent antimycobacterial activity against M. tuberculosis with MIC values of 2.3-16.9 µM. Treatment of the MMNAT enzyme with this set of inhibitors resulted in an irreversible time-dependent inhibition of NAT activity. Here we investigate the mechanism of NAT inhibition by studying protein-ligand interactions using mass spectrometry in combination with enzyme analysis and structure determination. We propose a covalent mechanism of NAT inhibition that involves the formation of a reactive intermediate and selective cysteine residue modification. These piperidinols present a unique class of antimycobacterial compounds that have a novel mode of action different from known anti-tubercular drugs
Judicial Candidates’ Right to Lie
, the Supreme Court struck down a law forbidding certain judicial campaign speech. A decade later, the Court in United States v. Alvarez ruled that factually false statements do not constitute categorically unprotected expression under the First Amendment. Together, these two holdings, along with the Court’s wider protection of political expression and disapproval of content-based restrictions, cast serious doubt on states’ ability to ban false and misleading speech by judicial candidates. Commonly known as the misrepresent clause, this prohibition has intuitive appeal in light of judges’ responsibilities and still exists in many states. Given the provision’s vulnerability to challenge, however, states may be able to avert chronic fabrication by judicial candidates only by removing its ultimate source—judicial elections themselves
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