22,602 research outputs found
Spectral Estimates and Non-Selfadjoint Perturbations of Spheroidal Wave Operators
We derive a spectral representation for the oblate spheroidal wave operator
which is holomorphic in the aspherical parameter in a neighborhood of
the real line. For real , estimates are derived for all eigenvalue gaps
uniformly in .
The proof of the gap estimates is based on detailed estimates for complex
solutions of the Riccati equation. The spectral representation for complex
is derived using the theory of slightly non-selfadjoint perturbations.Comment: 33 pages, LaTeX, 3 figures, typo in Lemma 4.1 corrected (published
version
Subarcsecond Imaging of the NGC 6334 I(N) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate
Using the SMA and VLA, we have imaged the massive protocluster NGC6334I(N) at
high angular resolution (0.5"~650AU) from 6cm to 0.87mm, detecting 18 new
compact continuum sources. Three of the new sources are coincident with
previously-identified water masers. Together with the previously-known sources,
these data bring the number of likely protocluster members to 25 for a
protostellar density of ~700 pc^-3. Our preliminary measurement of the
Q-parameter of the minimum spanning tree is 0.82 -- close to the value for a
uniform volume distribution. All of the (nine) sources with detections at
multiple frequencies have SEDs consistent with dust emission, and two (SMA1b
and SMA4) also have long wavelength emission consistent with a central
hypercompact HII region. Thermal spectral line emission, including CH3CN, is
detected in six sources: LTE model fitting of CH3CN(J=12-11) yields
temperatures of 72-373K, confirming the presence of multiple hot cores. The
fitted LSR velocities range from -3.3 to -7.0 km/s, with an unbiased mean
square deviation of 2.05 km/s, implying a dynamical mass of 410+-260 Msun for
the protocluster. From analysis of a wide range of hot core molecules, the
kinematics of SMA1b are consistent with a rotating, infalling Keplerian disk of
diameter 800AU and enclosed mass of 10-30 Msun that is perpendicular (within 1
degree) to the large-scale bipolar outflow axis. A companion to SMA1b at a
projected separation of 0.45" (590AU; SMA1d), which shows no evidence of
spectral line emission, is also confirmed. Finally, we detect one 218.440GHz
and several 229.7588GHz Class-I methanol masers.Comment: 54 pages, 11 figures. Accepted for publication in The Astrophysical
Journal. Version 2: Keywords updated, and three "in press" citations updated
to journal reference. Version 3: corrected the error in the quantum numbers
of the 218 GHz methanol transition in the text and in Table 8. For a PDF
version with full-resolution figures, see
http://www.cv.nrao.edu/~thunter/papers/ngc6334in2014.pd
Human behavioural analysis with self-organizing map for ambient assisted living
This paper presents a system for automatically classifying the resting location of a moving object in an indoor environment. The system uses an unsupervised neural network (Self Organising Feature Map) fully implemented on a low-cost, low-power automated home-based surveillance system, capable of monitoring activity level of elders living alone independently. The proposed system runs on an embedded platform with a specialised ceiling-mounted video sensor for intelligent activity monitoring. The system has the ability to learn resting locations, to measure overall activity levels and to detect specific events such as potential falls. First order motion information, including first order moving average smoothing, is generated from the 2D image coordinates (trajectories). A novel edge-based object detection algorithm capable of running at a reasonable speed on the embedded platform has been developed. The classification is dynamic and achieved in real-time. The dynamic classifier is achieved using a SOFM and a probabilistic model. Experimental results show less than 20% classification error, showing the robustness of our approach over others in literature with minimal power consumption. The head location of the subject is also estimated by a novel approach capable of running on any resource limited platform with power constraints
A developmental investigation of the relationship between appraisals and peer self-esteem in children experiencing peer-aggression
Transactional models of stress and coping emphasize the role played by cognitive appraisals in determining psychological adjustment (Lazarus, 1999). This proposition has been supported by research examining young people's adjustment in relation to family conflict and break-up (Grych et al., 1992). Furthermore, this literature suggests that there is a change in the relationship between appraisals and adjustment at around 10 years of age: specificity of appraisal type (e.g. threat, blame) becomes relevant to outcome after 10 years, whereas before 10 there are either no effects of appraisal on adjustment or a diffuse effect of 'negative' appraisals more generally (Jouriles et al., 2000). However, it is currently unclear whether this developmental progression can be generalized from familial- to social-stressors experienced by children and young people. The current study therefore evaluates the model within the context of a commonly experienced social childhood stressor: peer-aggression
First Results from a 1.3 cm EVLA Survey of Massive Protostellar Objects: G35.03+0.35
We have performed a 1.3 centimeter survey of 24 massive young stellar objects
(MYSOs) using the Expanded Very Large Array (EVLA). The sources in the sample
exhibit a broad range of massive star formation signposts including Infrared
Dark Clouds (IRDCs), UCHII regions, and extended 4.5 micron emission in the
form of Extended Green Objects (EGOs). In this work, we present results for
G35.03+0.35 which exhibits all of these phenomena. We simultaneously image the
1.3 cm ammonia (1,1) through (6,6) inversion lines, four methanol transitions,
two H recombination lines, plus continuum at 0.05 pc resolution. We find three
areas of thermal ammonia emission, two within the EGO (designated the NE and SW
cores) and one toward an adjacent IRDC. The NE core contains an UCHII region
(CM1) and a candidate HCHII region (CM2). A region of non-thermal, likely
masing ammonia (3,3) and (6,6) emission is coincident with an arc of 44 GHz
methanol masers. We also detect two new 25 GHz Class I methanol masers. A
complementary Submillimeter Array 1.3 mm continuum image shows that the
distribution of dust emission is similar to the lower-lying ammonia lines, all
peaking to the NW of CM2, indicating the likely presence of an additional MYSO
in this protocluster. By modeling the ammonia and 1.3 mm continuum data, we
obtain gas temperatures of 20-220 K and masses of 20-130 solar. The diversity
of continuum emission properties and gas temperatures suggest that objects in a
range of evolutionary states exist concurrently in this protocluster.Comment: To appear in Astrophysical Journal Letters Special Issue on the EVLA.
16 pages, 3 figures. Includes the complete version of Figure 3, which was
unable to fit into the journal article due to the number of panel
The Protocluster G18.67+0.03: A Test Case for Class I Methanol Masers as Evolutionary Indicators for Massive Star Formation
We present high angular resolution Submillimeter Array (SMA) and Karl G.
Jansky Very Large Array (VLA) observations of the massive protocluster
G18.67+0.03. Previously targeted in maser surveys of GLIMPSE Extended Green
Objects (EGOs), this cluster contains three Class I methanol maser sources,
providing a unique opportunity to test the proposed role of Class I masers as
evolutionary indicators for massive star formation. The millimeter observations
reveal bipolar molecular outflows, traced by 13CO(2-1) emission, associated
with all three Class I maser sources. Two of these sources (including the EGO)
are also associated with 6.7 GHz Class II methanol masers; the Class II masers
are coincident with millimeter continuum cores that exhibit hot core line
emission and drive active outflows, as indicated by the detection of SiO(5-4).
In these cases, the Class I masers are coincident with outflow lobes, and
appear as clear cases of excitation by active outflows. In contrast, the third
Class I source is associated with an ultracompact HII region, and not with
Class II masers. The lack of SiO emission suggests the 13CO outflow is a relic,
consistent with its longer dynamical timescale. Our data show that massive
young stellar objects associated only with Class I masers are not necessarily
young, and provide the first unambiguous evidence that Class I masers may be
excited by both young (hot core) and older (UC HII) MYSOs within the same
protocluster.Comment: Astrophysical Journal Letters, accepted. emulateapj, 7 pages
including 4 figures and 1 table. Figures compressed. v2: coauthor affiliation
updated, emulateapj versio
The effects of peer influence on adolescent pedestrian road-crossing decisions
Objective: Adolescence is a high-risk period for pedestrian injury. It is also a time of heightened susceptibility to peer influence. The aim of this research was to examine the effects of peer influence on the pedestrian road-crossing decisions of adolescents.
Methods: Using 10 videos of road-crossing sites, 80 16- to 18-year-olds were asked to make pedestrian road-crossing decisions. Participants were assigned to one of 4 experimental conditions: negative peer (influencing unsafe decisions), positive peer (influencing cautious decisions), silent peer (who observed but did not comment), and no peer (the participant completed the task alone). Peers from the adolescent’s own friendship group were recruited to influence either an unsafe or a cautious decision.
Results: Statistically significant differences were found between peer conditions. Participants least often identified safe road-crossing
sites when accompanied by a negative peer and more frequently identified dangerous road-crossing sites when accompanied by a positive peer. Both cautious and unsafe comments from a peer influenced adolescent pedestrians’ decisions.
Conclusions: These findings showed that road-crossing decisions of adolescents were influenced by both unsafe and cautious comments from their peers. The discussion highlighted the role that peers can play in both increasing and reducing adolescent risk-taking
A Putative ABC Transporter, HatABCDE, Is among Molecular Determinants of Pyomelanin Production in Pseudomonas aeruginosa
Pyomelanin overproduction is a common phenotype among Pseudomonas aeruginosa isolates recovered from cystic fibrosis and urinary tract infections. Its prevalence suggests that it contributes to the persistence of the producing microbial community, yet little is known about the mechanisms of its production. Using transposon mutagenesis, we identified factors that contribute to melanogenesis in a clinical isolate of P. aeruginosa. In addition to two enzymes already known to be involved in its biosynthesis (homogentisate dioxygenase and hydroxyphenylpyruvate dioxygenase), we identified 26 genes that encode regulatory, metabolic, transport, and hypothetical proteins that contribute to the production of homogentisic acid (HGA), the monomeric precursor of pyomelanin. One of these, PA14_57880, was independently identified four times and is predicted to encode the ATP-binding cassette of an ABC transporter homologous to proteins in Pseudomonas putida responsible for the extrusion of organic solvents from the cytosol. Quantification of HGA production by P. aeruginosa PA14 strains missing the predicted subcomponents of this transporter confirmed its role in HGA production: mutants unable to produce the ATP-binding cassette (PA14_57880) or the permease (PA14_57870) produced substantially less extracellular HGA after growth for 20 h than the parental strain. In these mutants, concurrent accumulation of intracellular HGA was observed. In addition, quantitative real-time PCR revealed that intracellular accumulation of HGA elicits upregulation of these transport genes. Based on their involvement in homogentisic acid transport, we rename the genes of this operon hatABCDE
Extended brief intervention to address alcohol misuse in people with mild to moderate intellectual disabilities living in the community (EBI-ID): study protocol for a randomised controlled trial.
There is some evidence that people with intellectual disabilities who live in the community are exposed to the same risks of alcohol use as the rest of the population. Various interventions have been evaluated in the general population to tackle hazardous or harmful drinking and alcohol dependence, but the literature evaluating interventions is very limited regarding intellectual disabilities. The National Institute for Health and Clinical Excellence recommends that brief and extended brief interventions be used to help young persons and adults who have screened as positive for hazardous and harmful drinking. The objective of this trial is to investigate the feasibility of adapting and delivering an extended brief intervention (EBI) to persons with mild/moderate intellectual disability who live in the community and whose level of drinking is harmful or hazardous
- …