1,325 research outputs found
Public Health Laboratories: Unprepared and Overwhelmed
Addresses the role of public health labs within the public health system and their ability to respond to specific chemical weapon events. Provides recommendations for improving response to terrorism as well as more conventional threats
Cooling Techniques for Trapped Ions
This book chapter gives an introduction to, and an overview of, methods for
cooling trapped ions. The main addressees are researchers entering the field.
It is not intended as a comprehensive survey and historical account of the
extensive literature on this topic. We present the physical ideas behind
several cooling schemes, outline their mathematical description, and point to
relevant literature useful for a more in-depth study of this topic.Comment: Part of the Proceedings of the Les Houches Winter School on the
Physics with Trapped Charged Particles held in January 2012. References
updated in mid 201
Excision for deformation K-theory of free products
Associated to a discrete group , one has the topological category of
finite dimensional (unitary) -representations and (unitary) isomorphisms.
Block sums provide this category with a permutative structure, and the
associated -theory spectrum is Carlsson's deformation -theory of G. The
goal of this paper is to examine the behavior of this functor on free products.
Our main theorem shows the square of spectra associated to (considered as
an amalgamated product over the trivial group) is homotopy cartesian. The proof
uses a general result regarding group completions of homotopy commutative
topological monoids, which may be of some independent interest.Comment: 32 pages, 1 figure. Final version: The title has changed, and the
paper has been substantially revised to improve clarit
Wage differentials for temporary services work: evidence from administrative data
We use administrative data from the unemployment insurance system State of Washington to study the magnitude of the wage differential associated with work in the temporary services industry. We find that temp wage rates are 15% to 20% below the levels that might have been expected based on trends during other periods in workers' careers even after controlling for differences between temps and other workers. Comparing temp wages immediately before and after temp work or to the wages on non-temp jobs begun during the same period as workers were in the temp industry yields estimates of the temp work penalty as low as 10%.Wages ; Temporary employees
Testing the Hubble Law with the IRAS 1.2 Jy Redshift Survey
We test and reject the claim of Segal et al. (1993) that the correlation of
redshifts and flux densities in a complete sample of IRAS galaxies favors a
quadratic redshift-distance relation over the linear Hubble law. This is done,
in effect, by treating the entire galaxy luminosity function as derived from
the 60 micron 1.2 Jy IRAS redshift survey of Fisher et al. (1995) as a distance
indicator; equivalently, we compare the flux density distribution of galaxies
as a function of redshift with predictions under different redshift-distance
cosmologies, under the assumption of a universal luminosity function. This
method does not assume a uniform distribution of galaxies in space. We find
that this test has rather weak discriminatory power, as argued by Petrosian
(1993), and the differences between models are not as stark as one might expect
a priori. Even so, we find that the Hubble law is indeed more strongly
supported by the analysis than is the quadratic redshift-distance relation. We
identify a bias in the the Segal et al. determination of the luminosity
function, which could lead one to mistakenly favor the quadratic
redshift-distance law. We also present several complementary analyses of the
density field of the sample; the galaxy density field is found to be close to
homogeneous on large scales if the Hubble law is assumed, while this is not the
case with the quadratic redshift-distance relation.Comment: 27 pages Latex (w/figures), ApJ, in press. Uses AAS macros,
postscript also available at
http://www.astro.princeton.edu/~library/preprints/pop682.ps.g
The Uncertainty of Fluxes
In the ordinary quantum Maxwell theory of a free electromagnetic field,
formulated on a curved 3-manifold, we observe that magnetic and electric fluxes
cannot be simultaneously measured. This uncertainty principle reflects torsion:
fluxes modulo torsion can be simultaneously measured. We also develop the
Hamilton theory of self-dual fields, noting that they are quantized by
Pontrjagin self-dual cohomology theories and that the quantum Hilbert space is
Z/2-graded, so typically contains both bosonic and fermionic states.
Significantly, these ideas apply to the Ramond-Ramond field in string theory,
showing that its K-theory class cannot be measured.Comment: 33 pages; minor modifications for publication in Commun. Math. Phy
Altitude-Loss Optimal Glides in Engine Failure Emergencies -- Accounting for Ground Obstacles and Wind
Engine failure is a recurring emergency in General Aviation and fixed-wing
UAVs, often requiring the pilot or remote operator to carry out carefully
planned glides to safely reach a candidate landing strip. We tackle the problem
of minimizing the altitude loss of a thrustless aircraft flying towards a
designated target position. Extending previous work on optimal glides without
obstacles, we consider here trajectory planning of optimal gliding in the the
presence of ground obstacles, while accounting for wind effects. Under
simplifying model assumptions, in particular neglecting the effect of turns, we
characterize the optimal solution as comprising straight glide segments between
iteratively-determined extreme points on the obstacles. Consequently, the
optimal trajectory is included in an iteratively-defined reduced visibility
graph, and can be obtained by a standard graph search algorithm, such as A.
We further quantify the effect of turns to verify a safe near-optimal glide
trajectory. We apply our algorithm on a Cessna 172 model, in realistic
scenarios, demonstrating both the altitude-loss optimal trajectory calculation,
and determination of airstrip reachability
A Compact Microchip-Based Atomic Clock Based on Ultracold Trapped Rb Atoms
We propose a compact atomic clock based on ultracold Rb atoms that are
magnetically trapped near the surface of an atom microchip. An interrogation
scheme that combines electromagnetically-induced transparency (EIT) with
Ramsey's method of separated oscillatory fields can achieve atomic shot-noise
level performance of 10^{-13}/sqrt(tau) for 10^6 atoms. The EIT signal can be
detected with a heterodyne technique that provides noiseless gain; with this
technique the optical phase shift of a 100 pW probe beam can be detected at the
photon shot-noise level. Numerical calculations of the density matrix equations
are used to identify realistic operating parameters at which AC Stark shifts
are eliminated. By considering fluctuations in these parameters, we estimate
that AC Stark shifts can be canceled to a level better than 2*10^{-14}. An
overview of the apparatus is presented with estimates of duty cycle and power
consumption.Comment: 15 pages, 11 figures, 5 table
Rolul central al prelungirilor citoplasmatice ale podocitelor în condiții de normă și boli glomerulare
Background. Podocytes cells are part of the filtration barrier that prevent loss of proteins into urine. Podocytes injury
that presents in various range of diseases result in proteinuria. The mechanisms of injuries can vary, but all of them
lead to the foot process effacement of podocytes. Objective
of the study. Studying the morphology and normal function
of the podocytes foot process and of associated changes of
them within glomerular diseases. Material and Methods.
The research is based on literary sources that were analyzed using PubMed, NCBI and Medline published within
the period of 2012-2022. Results. The analyzed research showed that the podocyte foot processes are attached
to the glomerular capillaries at the glomerular basement
membrane (GBM) by forming intercellular junctions that
form slit diaphragm of filtration barrier. Morphologically,
the podocytes are atypical polarized epithelial cells that are
divided into 3 separate structural and functional elements:
a large cell body, major extending processes, and minor foot
processes. The apical domain is negatively charged, which
is limiting the passage of albumin into urine. The injured
podocytes undergo effacement, and in result reduction of
filtration barrier function and proteinuria. Conclusion. The
podocyte injury lead to impaired of the filtration barrier
function. The injury to the podocyte result in effacement,
that is part of the pathophysiological processes in variety of
disease process, which injured the podocyte, and result in
nephrotic syndrome.Introducere. Podocitele, parte componentă din bariera de
filtrare, previn pierderea proteinelor în urină. Leziunile podocitelor, prezente într-un șir de boli renale, duc la proteinurie. Mecanismele leziunilor sunt variate și duc la atrofierea prelungirii citoplasmatice a podocitului. Scopul lucrării. Studierea morfologiei și funcției normale a prelungirii
citoplasmatice ale podocitelor și a modificărilor asociate
acestora în cadrul bolilor glomerulare. Material și Metode. Cercetarea se bazează pe surse bibliografice care au fost
analizate folosind PubMed, NCBI și Medline, publicate în
perioada 2012-2022. Rezultate. Lucrările analizate au evidențiat că prelungirile podocitelor sunt atașate de capilarele glomerulare la nivelul membranei bazale (GBM) prin formarea de joncțiuni intercelulare, care realizează fantele barierei de filtrare. Din punct de vedere morfologic, podocitele
sunt celule epiteliale polarizate atipice, care sunt împărțite
în 3 domenii structurale și funcționale diferite: corp celular,
prelungirile primare și prelungirile secundare. Domeniul
apical este încărcat negativ, ceea ce limitează trecerea albuminei în urină. Podocitele lezate sunt supuse atrofierii și, ca
urmare, apare proteinuria și se reduce funcția barierei de
filtrare. Concluzii. Leziunile podocitelor conduc la afectarea funcției barierei de filtrare. Leziunea podocitului rezultă
în atrofierea prelungirilor, urmare proceselor fiziopatologic
în cadrul unui șir de boli renale, care duc la uzarea podocitului și la sindrom nefrotic
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