59 research outputs found
Modeling magnetospheric fields in the Jupiter system
The various processes which generate magnetic fields within the Jupiter
system are exemplary for a large class of similar processes occurring at other
planets in the solar system, but also around extrasolar planets. Jupiter's
large internal dynamo magnetic field generates a gigantic magnetosphere, which
is strongly rotational driven and possesses large plasma sources located deeply
within the magnetosphere. The combination of the latter two effects is the
primary reason for Jupiter's main auroral ovals. Jupiter's moon Ganymede is the
only known moon with an intrinsic dynamo magnetic field, which generates a
mini-magnetosphere located within Jupiter's larger magnetosphere including two
auroral ovals. Ganymede's magnetosphere is qualitatively different compared to
the one from Jupiter. It possesses no bow shock but develops Alfv\'en wings
similar to most of the extrasolar planets which orbit their host stars within
0.1 AU. New numerical models of Jupiter's and Ganymede's magnetospheres
presented here provide quantitative insight into the processes that maintain
these magnetospheres. Jupiter's magnetospheric field is approximately
time-periodic at the locations of Jupiter's moons and induces secondary
magnetic fields in electrically conductive layers such as subsurface oceans. In
the case of Ganymede, these secondary magnetic fields influence the oscillation
of the location of its auroral ovals. Based on dedicated Hubble Space Telescope
observations, an analysis of the amplitudes of the auroral oscillations
provides evidence that Ganymede harbors a subsurface ocean. Callisto in
contrast does not possess a mini-magnetosphere, but still shows a perturbed
magnetic field environment. Callisto's ionosphere and atmospheric UV emission
is different compared to the other Galilean satellites as it is primarily been
generated by solar photons compared to magnetospheric electrons.Comment: Chapter for Book: Planetary Magnetis
On the verge of Umdeutung in Minnesota: Van Vleck and the correspondence principle (Part One)
In October 1924, the Physical Review, a relatively minor journal at the time,
published a remarkable two-part paper by John H. Van Vleck, working in virtual
isolation at the University of Minnesota. Van Vleck combined advanced
techniques of classical mechanics with Bohr's correspondence principle and
Einstein's quantum theory of radiation to find quantum analogues of classical
expressions for the emission, absorption, and dispersion of radiation. For
modern readers Van Vleck's paper is much easier to follow than the famous paper
by Kramers and Heisenberg on dispersion theory, which covers similar terrain
and is widely credited to have led directly to Heisenberg's "Umdeutung" paper.
This makes Van Vleck's paper extremely valuable for the reconstruction of the
genesis of matrix mechanics. It also makes it tempting to ask why Van Vleck did
not take the next step and develop matrix mechanics himself.Comment: 82 page
As aves do rio Peixoto de Azevedo, Mato Grosso, Brasil
<abstract language="eng">A check-list of the birds of the rio Peixoto de Azevedo, Mato Grosso, Brazil (10Âş 10' S, 54Âş 50' W) is presented, based on collections prepared by Werner Bokermann and EmĂlio Dente during the months of July and August, 1976; June through August, 1977; August of 1978; March, May, June, August and October, 1979; August of 1980 and only sporadically after these dates. Each species account includes the date that specimens were collected, gonad development, weight, color of the soft parts (iris, bill and tarsus), and, when necessary, notes on systematics. Measurements are presented in millimeters and weights in grams, with the mean of the sample expressed between parentheses. Theses data are yet scanty in brazilian ornithological literature
The impact of investment behaviour for individual welfare
The industrialized world has experienced a demographic shift that is straining public pension systems. Employer-sponsored pension plans change from defined benefit to defined contribution. More emphasis is put on individually managed retirement funds. One concern with this movement is the potential negative effect on individual welfare if households' investment behaviour is suboptimal. Using micro-level US data, we compare the optimal utility computed using a lifecycle model with the actual utility as reflected in empirical asset allocation choices. Average estimated welfare costs are below 3% of households' endowment (assets and human capital); yet specific population groups experience higher welfare costs
A Case of Successful Thromboelastographic Guided Resuscitation after Postpartum Hemorrhage and Cardiac Arrest
Amniotic fluid embolism (AFE) is an unusual cause of life threatening peri partum hemorrhage (PPH). AFE resuscitation is often associated with renal and respiratory insufficiency, and a coagulopathy similar to disseminated intravascular coagulation (DIC). Resuscitation requires immediate recognition and limited use of crystalloid. We present a case of PPH caused by AFE with resultant cardiac arrest, renal and respiratory failure, and DIC-like coagulopathy, whose successful resuscitation was guided by perfusionist-directed serial thromboelastography (TEG). Viscoelastic tests (VET)s, including the TEG and rotational thromboelastometry (ROTEM), may provide more individualized blood component therapy (BCT) in the treatment of severe PPH associated with AFE as has been previously noted with trauma resuscitation in the literature. However, VET’s efficacy is often limited by a lack of standardization, quality assurance norms, and consistent operator proficiency. We suggest that there may be a role for perfusionsts adept at utilizing TEG in the optimization of BCT and adjunctive hemostatic agents in severely hemorrhagic patients. This patient’s successful resuscitation demonstrates the importance of resuscitation guided by the perfusionist or other medical professionals with expertise in TEG guided resuscitation and how the administration of specific blood products and hemostatic agents guided by the TEG can help optimize patient outcomes in comparison to traditional 1:1:1 packed red blood cells (PRBC) /fresh frozen plasma (FFP) /platelets ratios given to severely hemorrhaging patients
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