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The people\u27s universities in the USSR : a description and analysis of a large-scale nonformal educational program.
The Stellar Population of h and chi Persei: Cluster Properties, Membership, and the Intrinsic Colors and Temperatures of Stars
(Abridged) From photometric observations of 47,000 stars and
spectroscopy of 11,000 stars, we describe the first extensive study of
the stellar population of the famous Double Cluster, h and Persei, down
to subsolar masses. Both clusters have E(B-V) 0.52--0.55 and dM =
11.8--11.85; the halo population, while more poorly constrained, likely has
identical properties. As determined from the main sequence turnoff, the
luminosity of M supergiants, and pre-main sequence isochrones, ages for h
Persei, Persei and the halo population all converge on 14 Myr.
From these data, we establish the first spectroscopic and photometric
membership lists of cluster stars down to early/mid M dwarfs. At minimum, there
are 5,000 members within 10' of the cluster centers, while the entire h
and Persei region has at least 13,000 and as many as 20,000
members. The Double Cluster contains 8,400 M of stars
within 10' of the cluster centers. We estimate a total mass of at least 20,000
M. We conclude our study by outlining outstanding questions regarding
the properties of h and Persei. From comparing recent work, we compile a
list of intrinsic colors and derive a new effective temperature scale for O--M
dwarfs, giants, and supergiants.Comment: 88 pages, many figures, Accepted for publication in The Astrophysical
Journal Supplements. Contact lead author for version with high-resolution
figure
Urothelial cells may indicate underlying bacteriuria in pregnancy at term: a comparative study
BACKGROUND: Urinary tract infection is common in pregnancy. Urine is sampled from by mid-stream collection (MSU). If epithelial cells are detected, contamination by vulvo-vagial skin and skin bacteria is assumed. Outside pregnancy, catheter specimen urine (CSU) is considered less susceptible to contamination. We compared MSU and CSU methods in term pregnancy to test these assumptions.
METHODS: Healthy pregnant women at term gestation (n = 32, median gestation 38 + 6 weeks, IQR 37 + 6–39 + 2) undergoing elective caesarean section provided a MSU and CSU for paired comparison that were each analysed for bacterial growth and bladder distress by fresh microscopy, sediment culture and immunofluorescent staining. Participants completed a detailed questionnaire on lower urinary tract symptoms. Epithelial cells found in urine were tested for urothelial origin by immunofluorescent staining of Uroplakin III (UP3), a urothelial cell surface glycoprotein. Urothelial cells with closely associated bacteria, or “clue cells”, were also counted. Wilcoxons signed rank test was used for paired analysis.
RESULTS: Women reported multiple lower urinary tract symptoms (median 3, IQR 0–8). MSU had higher white blood cell counts (median 67 vs 46, z = 2.75, p = 0.005) and epithelial cell counts (median 41 vs 22, z = 2.57, p = 0.009) on fresh microscopy. The proportion of UP3+ cells was not different (0.920 vs 0.935, z = 0.08, p = 0.95), however MSU had a higher proportion of clue cells (0.978 vs 0.772, z = 3.17, p = 0.001). MSU had more bacterial growth on sediment culture compared to CSU specimens (median 8088 total cfu/ml vs 0, z = 4.86, p = 0.001). Despite this, routine laboratory cultures reported a negative screening culture for 40.6% of MSU specimens.
CONCLUSION: Our findings have implications for the correct interpretation of MSU findings in term pregnancy. We observed that MSU samples had greater bacterial growth and variety when compared to CSU samples. The majority of epithelial cells in both MSU and CSU samples were urothelial in origin, implying no difference in contamination. MSU samples had a higher proportion of clue cells to UP3+ cells, indicating a greater sensitivity to bacterial invasion. Urinary epithelial cells should not be disregarded as contamination, instead alerting us to underlying bacterial activity
Magnetic field generation in finite beam plasma system
For finite systems boundaries can introduce remarkable novel features. A well
known example is the Casimir effect [1, 2] that is observed in quantum
electrodynamic systems. In classical systems too novel effects associated with
finite boundaries have been observed, for example the surface plasmon mode [3]
that appears when the plasma has a finite extension. In this work a novel
instability associated with the finite transverse size of a beam owing through
a plasma system has been shown to exist. This instability leads to distinct
characteristic features of the associated magnetic field that gets generated.
For example, in contrast to the well known unstable Weibel mode of a beam
plasma system which generates magnetic field at the skin depth scale, this
instability generates magnetic field at the scales length of the transverse
beam dimension [4]. The existence of this new instability is demonstrated by
analytical arguments and by simulations conducted with the help of a variety of
Particle - In - Cell (PIC) codes (e.g. OSIRIS, EPOCH, PICPSI). Two fluid
simulations have also been conducted which confirm the observations.
Furthermore, laboratory experiments on laser plasma system also provides
evidence of such an instability mechanism at work
Performance Limits of Stochastic Sub-Gradient Learning, Part II: Multi-Agent Case
The analysis in Part I revealed interesting properties for subgradient
learning algorithms in the context of stochastic optimization when gradient
noise is present. These algorithms are used when the risk functions are
non-smooth and involve non-differentiable components. They have been long
recognized as being slow converging methods. However, it was revealed in Part I
that the rate of convergence becomes linear for stochastic optimization
problems, with the error iterate converging at an exponential rate
to within an neighborhood of the optimizer, for some and small step-size . The conclusion was established under weaker
assumptions than the prior literature and, moreover, several important problems
(such as LASSO, SVM, and Total Variation) were shown to satisfy these weaker
assumptions automatically (but not the previously used conditions from the
literature). These results revealed that sub-gradient learning methods have
more favorable behavior than originally thought when used to enable continuous
adaptation and learning. The results of Part I were exclusive to single-agent
adaptation. The purpose of the current Part II is to examine the implications
of these discoveries when a collection of networked agents employs subgradient
learning as their cooperative mechanism. The analysis will show that, despite
the coupled dynamics that arises in a networked scenario, the agents are still
able to attain linear convergence in the stochastic case; they are also able to
reach agreement within of the optimizer
Solar wind collisional heating
To properly describe heating in weakly collisional turbulent plasmas such as
the solar wind, inter-particle collisions should be taken into account.
Collisions can convert ordered energy into heat by means of irreversible
relaxation towards the thermal equilibrium. Recently, Pezzi et al. (Phys. Rev.
Lett., vol. 116, 2016, p. 145001) showed that the plasma collisionality is
enhanced by the presence of fine structures in velocity space. Here, the
analysis is extended by directly comparing the effects of the fully nonlinear
Landau operator and a linearized Landau operator. By focusing on the relaxation
towards the equilibrium of an out of equilibrium distribution function in a
homogeneous force-free plasma, here it is pointed out that it is significant to
retain nonlinearities in the collisional operator to quantify the importance of
collisional effects. Although the presence of several characteristic times
associated with the dissipation of different phase space structures is
recovered in both the cases of the nonlinear and the linearized operators, the
influence of these times is different in the two cases. In the linearized
operator case, the recovered characteristic times are systematically larger
than in the fully nonlinear operator case, this suggesting that fine velocity
structures are dissipated slower if nonlinearities are neglected in the
collisional operator
Locus model for space-time fabric and quantum indeterminacies
A simple locus model for the space-time fabric is presented and is compared
with quantum foam and random walk models. The induced indeterminacies in
momentum are calculated and it is shown that these space-time fabric
indeterminacies are, in most cases, negligible compared with the quantum
mechanical indeterminacies. This result restricts the possibilities of an
experimental observation of the space-time fabric
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