157 research outputs found
Determination of energy transfer parameters in Er<sup>3+</sup>-doped and Er<sup>3+</sup>, Pr<sup>3+</sup>-codoped ZBLAN glasses
Approccio alla lingua italiana per allievi stranieri - ALIAS
Contiene, di P. E. Balboni,
- "Approccio alla lingua italiana per allievi stranieri", pp. 55-71
- "Problemi interculturali nei rapporti con allievi stranieri e con le loro famiglie", pp. 73-90
- "La fomrazione dei docenti: i contenuti e gli strumenti di base", pp. 181-184
Luminous Infrared Galaxies with the Submillimeter Array: I. Survey Overview and the Central Gas to Dust Ratio
We present new data obtained with the Submillimeter Array for a sample of
fourteen nearby luminous and ultraluminous infrared galaxies. The galaxies were
selected to have luminosity distances D < 200 Mpc and far-infrared luminosities
log(L_FIR) > 11.4. The galaxies were observed with spatial resolutions of order
1 kpc in the CO J=3-2, CO J=2-1, 13CO J=2-1, and HCO+ J=4-3 lines as well as
the continuum at 880 microns and 1.3 mm. We have combined our CO and continuum
data to measure an average gas-to-dust mass ratio of 120 +/- 28 (rms deviation
109) in the central regions of these galaxies, very similar to the value of 150
determined for the Milky Way. This similarity is interesting given the more
intense heating from the starburst and possibly accretion activity in the
luminous infrared galaxies compared to the Milky Way. We find that the peak H_2
surface density correlates with the far-infrared luminosity, which suggests
that galaxies with higher gas surface densities inside the central kiloparsec
have a higher star formation rate. The lack of a significant correlation
between total H_2 mass and far-infrared luminosity in our sample suggests that
the increased star formation rate is due to the increased availability of
molecular gas as fuel for star formation in the central regions. In contrast to
previous analyses by other authors, we do not find a significant correlation
between central gas surface density and the star formation efficiency, as trace
by the ratio of far-infrared luminosity to nuclear gas mass. Our data show that
it is the star formation rate, not the star formation efficiency, that
increases with increasing central gas surface density in these galaxies.Comment: 66 pages, 39 figures, aastex preprint format; to be published in ApJ
Supplements. Version of paper with full resolution figures available at
http://www.physics.mcmaster.ca/~wilson/www_xfer/ULIRGS_publi
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New Ways of Being a Man: "Positive" Hegemonic Masculinity in Meditation-based Communities of Practice
Connell’s concept of hegemonic masculinity is often reduced to a singular construct, consisting of “toxic” traits viewed as detrimental to well-being. However, the concept allows for variation in hegemony, including the possibility of forms more conducive to well-being. Through in-depth interviews with thirty male meditators in the United Kingdom, we explored the social dimensions of meditation practice to examine its potential implications for well-being. Most participants became involved with “communities of practice” centered on meditation that promoted new local hegemonies, and these included ideals experienced as conducive to well-being, like abstinence. However, social processes associated with hegemony, like hierarchy and marginalization, were not overturned. Moreover, participants faced challenges enacting new practices in relation to the broader system of hegemonic masculinity—outside these communities—reporting censure. Our findings are cautionary for professionals seeking to encourage well-being behaviors: that is, there is potential for adaptation in men, yet complex social processes influence this change
Prediction of 7-year psychopathology from mother-infant joint attention behaviours: a nested case–control study
<br>Background: To investigate whether later diagnosis of psychiatric disorder can be predicted from analysis of mother-infant joint attention (JA) behaviours in social-communicative interaction at 12 months.</br>
<br>Method:
Using data from a large contemporary birth cohort, we examined 159 videos of a mother-infant interaction for joint attention behaviour when children were aged one year, sampled from within the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort. Fifty-three of the videos involved infants who were later considered to have a psychiatric disorder at seven years and 106 were same aged controls. Psychopathologies included in the case group were disruptive behaviour disorders, oppositional-conduct disorder, attention-deficit/hyperactivity disorder, pervasive development disorder, anxiety and depressive disorders. Psychiatric diagnoses were obtained using the Development and Wellbeing Assessment when the children were seven years old.</br> <br>Results: None of the three JA behaviours (shared look rate, shared attention rate and shared attention intensity) showed a significant association with the primary outcome of case–control status. Only shared look rate predicted any of the exploratory sub-diagnosis outcomes and was found to be positively associated with later oppositional-conduct disorders (OR [95% CI]: 1.5 [1.0, 2.3]; p = 0.041).</br><br>Conclusions: JA behaviours did not, in general, predict later psychopathology. However, shared look was positively associated with later oppositional-conduct disorders. This suggests that some features of JA may be early markers of later psychopathology. Further investigation will be required to determine whether any JA behaviours can be used to screen for families in need of intervention.</br>
Model Channel Ion Currents in NaCl - SPC/E Solution with Applied-Field Molecular Dynamics
Using periodic boundary conditions and a constant applied field, we have
simulated current flow through an 8.125 Angstrom internal diameter, rigid,
atomistic channel with polar walls in a rigid membrane using explicit ions and
SPC/E water. Channel and bath currents were computed from ten 10-ns
trajectories for each of 10 different conditions of concentration and applied
voltage. An electric field was applied uniformly throughout the system to all
mobile atoms. On average, the resultant net electric field falls primarily
across the membrane channel, as expected for two conductive baths separated by
a membrane capacitance. The channel is rarely occupied by more than one ion.
Current-voltage relations are concentration-dependent and superlinear at high
concentrations.Comment: Accepted for publication in Biophysical Journa
Prediction of 7-year psychopathology from mother-infant joint attention behaviours: a nested case-control study
Abstract Background: To investigate whether later diagnosis of psychiatric disorder can be predicted from analysis of mother-infant joint attention (JA) behaviours in social-communicative interaction at 12 months. Method: Using data from a large contemporary birth cohort, we examined 159 videos of a mother-infant interaction for joint attention behaviour when children were aged one year, sampled from within the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort. Fifty-three of the videos involved infants who were later considered to have a psychiatric disorder at seven years and 106 were same aged controls. Psychopathologies included in the case group were disruptive behaviour disorders, oppositional-conduct disorder, attentiondeficit/hyperactivity disorder, pervasive development disorder, anxiety and depressive disorders. Psychiatric diagnoses were obtained using the Development and Wellbeing Assessment when the children were seven years old
Reduced adhesion between cells and substrate confers selective advantage in bacterial colonies
Microbial colonies cultured on agar Petri dishes have become a model system
to study biological evolution in populations expanding in space. Processes such
as clonal segregation and gene surfing have been shown to be affected by
interactions between microbial cells and their environment. In this work we
investigate the role of mechanical interactions such as cell-surface adhesion.
We compare two strains of the bacterium E. coli: a wild-type strain and a
"shaved" strain that adheres less to agar. We show that the shaved strain has a
selective advantage over the wild type: although both strains grow with the
same rate in liquid media, the shaved strain produces colonies that expand
faster on agar. This allows the shaved strain outgrow the wild type when both
strains compete for space. We hypothesise that, in contrast to a more common
scenario in which selective advantage results from increased growth rate, the
higher fitness of the shaved strain is caused by reduced adhesion and friction
with the agar surface.Comment: 7 pages, 7 figures, submitted to the EPL Special Issue "Evolutionary
modeling and experimental evolution
Low-dose aspirin does not improve ovarian stimulation, endometrial response, or pregnancy rates for in vitro fertilization
BACKGROUND: The purpose of this study is to determine if low-dose aspirin improved ovarian stimulation, endometrial response, or IVF pregnancy rates in our program. METHODS: Retrospective analysis of 316 consecutive IVF cycles from 1995 through 2001. Aspirin 80 mg daily was initiated at the start of luteal leuprolide in 72 cycles. The 244 controls received no aspirin during treatment. RESULTS: The live birth rate in aspirin users was 29%, slightly lower compared to 41% in the no aspirin control group (p = 0.07). Implantation rates were 21% with aspirin and 30% in the control population (p = 0.01). There was no difference in the maximal endometrial thickness between aspirin and non-aspirin groups. The two groups were similar regarding age, gonadotropin ampules, embryos, number of embryos transferred, prior parity, diagnosis, use of intracytoplasmic sperm injection, and stimulation protocol. CONCLUSION: Low-dose aspirin was not beneficial to IVF patients in our program. Aspirin does not enhance endometrial thickness, augment the ovarian response, or improve pregnancy rates
Genome-wide fine-scale recombination rate variation in Drosophila melanogaster
Estimating fine-scale recombination maps of Drosophila from population genomic data is a challenging problem, in particular because of the high background recombination rate. In this paper, a new computational method is developed to address this challenge. Through an extensive simulation study, it is demonstrated that the method allows more accurate inference, and exhibits greater robustness to the effects of natural selection and noise, compared to a well-used previous method developed for studying fine-scale recombination rate variation in the human genome. As an application, a genome-wide analysis of genetic variation data is performed for two Drosophila melanogaster populations, one from North America (Raleigh, USA) and the other from Africa (Gikongoro, Rwanda). It is shown that fine-scale recombination rate variation is widespread throughout the D. melanogaster genome, across all chromosomes and in both populations. At the fine-scale, a conservative, systematic search for evidence of recombination hotspots suggests the existence of a handful of putative hotspots each with at least a tenfold increase in intensity over the background rate. A wavelet analysis is carried out to compare the estimated recombination maps in the two populations and to quantify the extent to which recombination rates are conserved. In general, similarity is observed at very broad scales, but substantial differences are seen at fine scales. The average recombination rate of the X chromosome appears to be higher than that of the autosomes in both populations, and this pattern is much more pronounced in the African population than the North American population. The correlation between various genomic features—including recombination rates, diversity, divergence, GC content, gene content, and sequence quality—is examined using the wavelet analysis, and it is shown that the most notable difference between D. melanogaster and humans is in the correlation between recombination and diversity
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