This book includes 13 papers concerning some of the recent progress in the theory of function spaces and its applications. The involved function spaces include Morrey and weak Morrey spaces, ...Hardy-type spaces, John–Nirenberg spaces, Sobolev spaces, and Besov and Triebel–Lizorkin spaces on different underlying spaces, and they are applied in the study of problems ranging from harmonic analysis to potential analysis and partial differential equations, such as the boundedness of paraproducts and Calderón operators, the characterization of pointwise multipliers, estimates of anisotropic logarithmic potential, as well as certain Dirichlet problems for the Schrödinger equation.
An economic historian argues that privately funded space exploration is not a new development, but a trend beginning with the astronomical observatories of the nineteenth centuryOver the last ...half-century there has been a rapid expansion in commerce off the surface of our planet. Nations and corporations have placed hundreds of satellites that provide billions of dollars' worth of communications, scientific, global positioning, and commercial services, while construction has been completed on humanity's ninth and largest space station. On the planet itself, government agencies, corporations, and individuals plan for the expansion of economic development to the lunar surface, asteroids, and Mars. The future of space exploration seems likely to include a mix of large government funded missions as well as independent private-sector missions.The Long Space Ageexamines the economic history of American space exploration and spaceflight, from early astronomical observatories to the International Space Station, and argues that the contemporary rise of private-sector efforts is the re-emergence of a long-run trend not a new phenomenon.
Projective versions of selection principles Bonanzinga, Maddalena; Cammaroto, Filippo; Matveev, Mikhail
Topology and its applications,
04/2010, Letnik:
157, Številka:
5
Journal Article
Recenzirano
Odprti dostop
All spaces are assumed to be Tychonoff. A space
X is called projectively
P
(where
P
is a topological property) if every continuous second countable image of
X is
P
. Characterizations of projectively ...Menger spaces
X in terms of continuous mappings
f
:
X
→
R
ω
, of Menger base property with respect to separable pseudometrics and a selection principle restricted to countable covers by cozero sets are given. If all finite powers of
X are projectively Menger, then all countable subspaces of
C
p
(
X
)
have countable fan tightness. The class of projectively Menger spaces contains all Menger spaces as well as all
σ-pseudocompact spaces, and all spaces of cardinality less than
d
. Projective versions of Hurewicz, Rothberger and other selection principles satisfy properties similar to the properties of projectively Menger spaces, as well as some specific properties. Thus,
X is projectively Hurewicz iff
C
p
(
X
)
has the Monotonic Sequence Selection Property in the sense of Scheepers;
βX is Rothberger iff
X is pseudocompact and projectively Rothberger. Embeddability of the countable fan space
V
ω
into
C
p
(
X
)
or
C
p
(
X
,
2
)
is characterized in terms of projective properties of
X.
To understand the health impact of long-duration spaceflight, one identical twin astronaut was monitored before, during, and after a 1-year mission onboard the International Space Station; his twin ...served as a genetically matched ground control. Longitudinal assessments identified spaceflight-specific changes, including decreased body mass, telomere elongation, genome instability, carotid artery distension and increased intima-media thickness, altered ocular structure, transcriptional and metabolic changes, DNA methylation changes in immune and oxidative stress-related pathways, gastrointestinal microbiota alterations, and some cognitive decline postflight. Although average telomere length, global gene expression, and microbiome changes returned to near preflight levels within 6 months after return to Earth, increased numbers of short telomeres were observed and expression of some genes was still disrupted. These multiomic, molecular, physiological, and behavioral datasets provide a valuable roadmap of the putative health risks for future human spaceflight.
Awake craniotomy (AC) is a common neurosurgical procedure for the resection of lesions in eloquent brain areas, which has the advantage of avoiding general anesthesia to reduce associated ...complications and costs. A significant resource limitation in low- and middle-income countries constrains the usage of AC.
To review the published literature on AC in African countries, identify challenges, and propose pragmatic solutions by practicing neurosurgeons in Africa.
We conducted a scoping review under Preferred Reporting Items for Systematic Reviews and Meta-Analysis-Scoping Review guidelines across 3 databases (PubMed, Scopus, and Web of Science). English articles investigating AC in Africa were included.
Nineteen studies consisting of 396 patients were included. Egypt was the most represented country with 8 studies (42.1%), followed by Nigeria with 6 records (31.6%). Glioma was the most common lesion type, corresponding to 120 of 396 patients (30.3%), followed by epilepsy in 71 patients (17.9%). Awake-awake-awake was the most common protocol used in 7 studies (36.8%). Sixteen studies (84.2%) contained adult patients. The youngest reported AC patient was 11 years old, whereas the oldest one was 92. Nine studies (47.4%) reported infrastructure limitations for performing AC, including the lack of funding, intraoperative monitoring equipment, imaging, medications, and limited human resources.
Despite many constraints, AC is being safely performed in low-resource settings. International collaborations among centers are a move forward, but adequate resources and management are essential to make AC an accessible procedure in many more African neurosurgical centers.
This book examines the drivers behind great power security competition in space to determine whether realistic strategic alternatives exist to further militarization.
Space is an area of increasing ...economic and military competition. This book offers an analysis of actions and events indicative of a growing security dilemma in space, which is generating an intensifying arms race between the US, China, and Russia. It explores the dynamics behind a potential future war in space and investigates methods of preventing an arms race from an international relations theory and military-strategy standpoint. The book is divided into three parts: the first section offers a broad discussion of the applicability of international relations theory to current conditions in space; the second is a direct application of theory to the space environment to determine whether competition or cooperation is the optimal strategic choice; the third section focuses on testing the hypotheses against reality, by analyzing novel alternatives to three major categories of space systems. The volume concludes with a study of the practical limitations of applying a strategy centered on commercialization as a method of defusing the orbital security dilemma.
This book will be of interest to students of space power, strategic studies, and international relations.
Philosophy of physics Maudlin, Tim
2012., 20120722, 2012, 2012-07-22, 20120101, Letnik:
11
eBook
This concise book introduces nonphysicists to the core philosophical issues surrounding the nature and structure of space and time, and is also an ideal resource for physicists interested in the ...conceptual foundations of space-time theory. Tim Maudlin's broad historical overview examines Aristotelian and Newtonian accounts of space and time, and traces how Galileo's conceptions of relativity and space-time led to Einstein's special and general theories of relativity. Maudlin explains special relativity with enough detail to solve concrete physical problems while presenting general relativity in more qualitative terms. Additional topics include the Twins Paradox, the physical aspects of the Lorentz-FitzGerald contraction, the constancy of the speed of light, time travel, the direction of time, and more.
Introduces nonphysicists to the philosophical foundations of space-time theory Provides a broad historical overview, from Aristotle to Einstein Explains special relativity geometrically, emphasizing the intrinsic structure of space-time Covers the Twins Paradox, Galilean relativity, time travel, and more Requires only basic algebra and no formal knowledge of physics
Ever since the space tether was first proposed by Tsiolkovsky, it has been extensively utilized in space missions, for attitude stabilization, momentum exchange, and space elevators. Developments in ...engineering technology and changes in the space environment have diversified the current applications for the space tether. New applications for the space tether include the Tethered Space Robot, Tethered Space Net, and Tethered Spacecraft Formation. These are quickly being adapted for in-orbit maintenance such as fueling service, orbit maneuvering, and active space debris capture/removal. The flexibility and elasticity of the space tether lead to complex issues with tethered space systems, including the mechanics design, dynamics modeling and analysis, and control scheme design. In this paper, we review several new applications for the space tether during service in orbit, and research the on structure, dynamics, and control of each application. This review is conducted to provide an overall summary of the space tether for On-Orbit Servicing, and further the conversation regarding possible research interests in the future.
Advances over the past decades in space flight technology have allowed U.S., Russian, and other space programs to not only increase the frequency of manned space flights but also to increase the ...duration of these flights. As such, a large body of knowledge has been developed regarding the ways in which space flight affects the health of the personnel involved. Now, for the first time, this body of clinical knowledge on how to diagnose and treat conditions that either develop during a mission or because of a mission has been compiled by Drs. Michael R. Barratt and Sam L. Pool of the NASA/Johnson Space Center.
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