Freedom and Self-Becoming in Karl Jaspers\u27 Existential Philosophy

One of the primary concerns of contemporary counseling literature appears to be the self, to what extent it owes its being to freedom on the one hand, and to environmental influences on the other. This paper does not pretend to resolve so complex an issue. It seeks rather to view the problem

Solid deuterium surface degradation at ultracold neutron sources

Solid deuterium (sD_2) is used as an efficient converter to produce ultracold neutrons (UCN). It is known that the sD_2 must be sufficiently cold, of high purity and mostly in its ortho-state in order to guarantee long lifetimes of UCN in the solid from which they are extracted into vacuum. Also the UCN transparency of the bulk sD_2 material must be high because crystal inhomogeneities limit the mean free path for elastic scattering and reduce the extraction efficiency. Observations at the UCN sources at Paul Scherrer Institute and at Los Alamos National Laboratory consistently show a decrease of the UCN yield with time of operation after initial preparation or later treatment (`conditioning') of the sD_2. We show that, in addition to the quality of the bulk sD_2, the quality of its surface is essential. Our observations and simulations support the view that the surface is deteriorating due to a build-up of D_2 frost-layers under pulsed operation which leads to strong albedo reflections of UCN and subsequent loss. We report results of UCN yield measurements, temperature and pressure behavior of deuterium during source operation and conditioning, and UCN transport simulations. This, together with optical observations of sD_2 frost formation on initially transparent sD_2 in offline studies with pulsed heat input at the North Carolina State University UCN source results in a consistent description of the UCN yield decrease.Comment: 15 pages, 22 figures, accepted by EPJ-

Pulse oximetry in the oesophagus

Pulse oximetry has been one of the most significant technological advances in clinical monitoring in the last two decades. Pulse oximetry is a non-invasive photometric technique that provides information about the arterial blood oxygen saturation (SpO(2)) and heart rate, and has widespread clinical applications. When peripheral perfusion is poor, as in states of hypovolaemia, hypothermia and vasoconstriction, oxygenation readings become unreliable or cease. The problem arises because conventional pulse oximetry sensors must be attached to the most peripheral parts of the body, such as finger, ear or toe, where pulsatile flow is most easily compromised. Since central blood flow may be preferentially preserved, this review explores a new alternative site, the oesophagus, for monitoring blood oxygen saturation by pulse oximetry. This review article presents the basic physics, technology and applications of pulse oximetry including photoplethysmography. The limitations of this technique are also discussed leading to the proposed development of the oesophageal pulse oximeter. In the majority, the report will be focused on the description of a new oesophageal photoplethysmographic/SpO(2) probe, which was developed to investigate the suitability of the oesophagus as an alternative monitoring site for the continuous measurement of SpO(2) in cases of poor peripheral circulation. The article concludes with a review of reported clinical investigations of the oesophageal pulse oximeter

Nuclear astrophysics: the unfinished quest for the origin of the elements

Half a century has passed since the foundation of nuclear astrophysics. Since then, this discipline has reached its maturity. Today, nuclear astrophysics constitutes a multidisciplinary crucible of knowledge that combines the achievements in theoretical astrophysics, observational astronomy, cosmochemistry and nuclear physics. New tools and developments have revolutionized our understanding of the origin of the elements: supercomputers have provided astrophysicists with the required computational capabilities to study the evolution of stars in a multidimensional framework; the emergence of high-energy astrophysics with space-borne observatories has opened new windows to observe the Universe, from a novel panchromatic perspective; cosmochemists have isolated tiny pieces of stardust embedded in primitive meteorites, giving clues on the processes operating in stars as well as on the way matter condenses to form solids; and nuclear physicists have measured reactions near stellar energies, through the combined efforts using stable and radioactive ion beam facilities. This review provides comprehensive insight into the nuclear history of the Universe and related topics: starting from the Big Bang, when the ashes from the primordial explosion were transformed to hydrogen, helium, and few trace elements, to the rich variety of nucleosynthesis mechanisms and sites in the Universe. Particular attention is paid to the hydrostatic processes governing the evolution of low-mass stars, red giants and asymptotic giant-branch stars, as well as to the explosive nucleosynthesis occurring in core-collapse and thermonuclear supernovae, gamma-ray bursts, classical novae, X-ray bursts, superbursts, and stellar mergers.Comment: Invited Review. Accepted for publication in "Reports on Progress in Physics" (version with low-resolution figures

Adverse effects of ocean acidification on early development of squid (Doryteuthis pealeii)

This study was supported by a WHOI Student Summer Fellowship and WHOI-MIT Joint Program, the Penzance Endowed Fund, the John E. and Anne W. Sawyer Endowed Fund and NSF Research Grant No. EF-1220034. Additional support came from NSF OCE 1041106 to ALC and DCM, and NOAA Sea Grant award #NA10OAR4170083 to ALC and DCM.Anthropogenic carbon dioxide (CO2) is being absorbed into the ocean, altering seawater chemistry, with potentially negative impacts on a wide range of marine organisms. The early life stages of invertebrates with internal and external aragonite structures may be particularly vulnerable to this ocean acidification. Impacts to cephalopods, which form aragonite cuttlebones and statoliths, are of concern because of the central role they play in many ocean ecosystems and because of their importance to global fisheries. Atlantic longfin squid (Doryteuthis pealeii), an ecologically and economically valuable taxon, were reared from eggs to hatchlings (paralarvae) under ambient and elevated CO2 concentrations in replicated experimental trials. Animals raised under elevated pCO2demonstrated significant developmental changes including increased time to hatching and shorter mantle lengths, although differences were small. Aragonite statoliths, critical for balance and detecting movement, had significantly reduced surface area and were abnormally shaped with increased porosity and altered crystal structure in elevated pCO2-reared paralarvae. These developmental and physiological effects could alter squid paralarvae behavior and survival in the wild, directly and indirectly impacting marine food webs and commercial fisheries.Publisher PDFPeer reviewe