Halo initial mass functions (IMFs) heavily biased toward white dwarf (WD)
precursors ~1-8 Msun have been suggested as a suitable mechanism for explaining
MACHO events. However, by simple chemical ...evolution argument, Gibson & Mould
(1997; GM97) pointed out that such WD-heavy IMFs (wdIMF) cause the
overproduction of carbon and nitrogen. We re-examine this problem using
numerical simulations.
The authors assessed whether (a) early illicit drug use predicted later risky sexual activity, (b) early risky sex predicted later illicit drug use, and (c) common factors affected both risky sexual ...behavior and illicit drug use. African American and Puerto Rican youth completed questionnaires in their classrooms at Time 1 (T1) and face-to-face interviews with the authors in their homes 5 years later at Time 2 (T2). Logistic regression analyses showed the association between T1 illicit drug use and T2 risky sexual activity and between T1 risky sexual behavior and T2 illicit drug use. With few exceptions, T1 illicit drug use was associated with all of the T2 risky sexual behaviors. After controlling for demographic factors, the authors found that multiple sex partners at T1 was not related to illicit drug use at T2. Condom use at T1 was related to illicit drug use at T2, whereas sexually transmitted diseases and adolescent pregnancy were not related to this drug use. The findings indicated that assessments of and treatments for substance use should focus on the risky sexual behaviors that seem to accompany illicit drug use.
This prospective observational study was aimed at evaluating the appropriateness of use of upper gastrointestinal endoscopy (UGE) in primary care in a country with open access to and high ...availability of the procedure.
Outpatients were consecutively included in two clinical settings: Setting A (20 primary care physicians during 4 weeks) and B (university-based outpatient clinic during 3 weeks). In patients undergoing UGE, appropriateness of referral was judged by explicit Swiss criteria developed by the RAND/UCLA panel method.
Patient visits (8135) were assessed. Six hundred eleven patients complained of upper gastrointestinal symptoms. Physicians decided to perform UGE in 63 of these patients. Twenty-five (40%) of the endoscopies were rated appropriate, 7 (11%) equivocal, and 31 (49%) inappropriate. Overuse of UGE occurred in 5.1% (setting A: 4.7%; setting B: 6.5%;
p = 0.39) of the patients who presented with upper gastrointestinal symptoms. The decision to perform UGE in previously untreated dyspeptic patients was the most common clinical situation resulting in overuse.
Inappropriate use of UGE is high in Switzerland. However, to better reflect primary care decision making, overuse should be related not only to patients referred for a medical test, but also to the number of patients who complain of the symptoms that would be investigated by the procedure.
Introduction: The intrinsic cardiac autonomic nervous system comprises interconnected epicardial ganglionated plexuses (GP) that are implicated in the initiation of atrial fibrillation (AF). GPs can ...be stimulated and functionally identified by delivering high frequency stimulation (HFS) within the local atrial refractory period, which can cause atrial ectopy and AF. These GPs are called ’ectopy-triggering GP‘ (ET-GP). Objective: To identify the immunohistochemical characteristics underlying an ectopy-triggering response with GP stimulation. Method: Four porcine hearts (4–5 months, 70–80 kg) were Langendorff-perfused. A 3.5 mm tip quadripolar ablation catheter was used for epicardial pacing at a fixed rate, and HFS was delivered within the local atrial refractory period (20 ms delay from pacing stimulus, 40 Hz, 10 V, 80 ms duration) using a custom-built stimulator. We tested globally around the left and right atria. Transmural dissection was performed at sites that induced ectopy or AF (ET-GP) and at sites with negative HFS response. We examined the tissues by brightfield microscopy, and by immunohistochemistry for identification of parasympathetic and sympathetic nerves, staining positive for choline acetyl transferase and tyrosine hydroxylase respectively. Immunohistochemistry on porcine sympathetic trunk and vagus nerve acted as positive controls. Results: Sixty-three HFS sites were tested, identifying 6 ET-GPs (10%) that evoked single ectopics and short runs of ectopy (Figure 1A). Six negative HFS sites were also analysed as controls. Sympathetic and parasympathetic nerves (Figure 1B) were identified in all ET-GP sites. One negative HFS site had no identifiable nerves. There were greater numbers of nerves in ET-GPs compared with negative HFS sites (41 ± 44 versus 16 ± 20, p=0.04; Figure 1C). The sympathetic nerve cross-sectional area was smaller in ET-GP sites compared with negative HFS (6,021µm2 ± 14,586 versus 22,786 µm2 ± 56,588, p<0.0001), though not significantly different for parasympathetic nerves (1,356 µm2 ± 2,127 versus 3,827 µm2 ± 10,156, p=0.06). We observed no differences in nerve distribution across the epicardium, myocardium or endocardium in both groups. Conclusions: HFS can reproducibly trigger atrial ectopy in Langendorff-perfused porcine hearts. Ectopy-triggering sites have significantly larger numbers of sympathetic nerves that are smaller in size than in negative HFS sites. These local differences in sympathetic and parasympathetic nerve distribution and quantity may account for the differential functional response to HFS. Image Omitted
Since 1966 all recently appointed consultants in general psychiatry in the United Kingdom have been asked to rate their training experiences. Four postal surveys have been made at three yearly ...intervals, of 574 consultants appointed in the period 1 October 1965--30 September 1978. This paper reports the findings from the responses of 162 consultants appointed 1975-1978. Fifty per cent, or fewer, reported satisfactory training in special forms of psychotherapy, addiction, work in the community, mental handicap, forensic psychiatry, administration, research, psychogeriatrics, work with longstay patients, rehabilitation, medico-legal work, group psychotherapy, work in a therapeutic community, child psychiatry epidemiology and postgraduate teaching. Those who had been at the Maudsley Hospital considered that they had experienced the best training, while those who had been at peripheral hospitals the worst. Progress has been made in the past 3 years, notably in the fields of individual psychotherapy, community work and forensic psychiatry.
Using stellar population synthesis techniques, we explore the photometric
signatures of white dwarf progenitor dominated galactic halos, in order to
constrain the fraction of halo mass that may be ...locked-up in white dwarf
stellar remnants. We first construct a 10^9 M_sun stellar halo using the
canonical Salpeter initial stellar mass distribution, and then allow for an
additional component of low- and intermediate-mass stars, which ultimately give
rise to white dwarf remnants. Microlensing observations towards the Large
Magellanic Cloud, coupled with several ground-based proper motion surveys, have
led to claims that in excess of 20% of the dynamical mass of the halo (10^12
M_sun) might be found in white dwarfs. Our results indicate that (1) even if
only 1% of the dynamical mass of the dark halo today could be attributed to
white dwarfs, their main sequence progenitors at high redshift (z ~ 3) would
have resulted in halos more than 100 times more luminous than those expected
from conventional initial mass functions alone, and (2) any putative halo white
dwarf progenitor dominated initial mass function component, regardless of its
dynamical importance, would be virtually impossible to detect at the
present-day, due to its extremely faint surface brightness.
Background: There is often substantial mismatch between the diameters of the pulmonary and aortic anuli in young patients with systemic outflow tract disease. To implant the autologous pulmonary ...valve in the aortic position under such circumstances, it is necessary to adapt the geometry of the systemic outflow tract. The effects of such adaptations on autograft function in children are not well known.
Methods: To determine factors predictive of autograft regurgitation, we analyzed 41 cases of children who have undergone the Ross procedure. The diameter of the pulmonary valve was greater (by at least 3 mm) than that of the aortic valve in 20 cases, equal (within 2 mm) in 12 cases, and less (by at least 3 mm) in nine cases, with differences ranging from +10 to –12 mm. In 12 patients with a larger pulmonary anulus, aortoventriculoplasty was used to correct the mismatch. In patients with a larger aortic anulus, the mismatch was corrected by gradual adjustment along the circumference of the autograft, rather than by tailoring of the native aortic anulus.
Results: At follow-up (median 31 months), two patients had undergone reoperation on the neoaortic valve for moderate regurgitation. In the remaining 38 cases, autograft regurgitation was as follows: none or trivial in 30, mild in seven, and moderate in one. There was no correlation between regurgitation and age, geometric mismatch, or previous or concurrent procedures.
Conclusions: Subtle technical factors that may result in distortion of the valve complex are probably more important determinants of autograft regurgitation than are indication for repair, geometric mismatch, or previous or concomitant outflow tract procedures. Significant mismatch of the semilunar anuli is not a contraindication to the Ross procedure in children. (J Thorac Cardiovasc Surg 1998;115:1255-63)
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