9,845 research outputs found
Plant diversity to support humans in a CELSS ground based demonstrator
A controlled ecological life support system (CELSS) for human habitation in preparation for future long duration space flights is considered. The success of such a system depends upon the feasibility of revitalization of food resources and the human nutritional needs which are to be met by these food resources. Edible higher plants are prime candidates for the photoautotrophic components of this system if nutritionally adequate diets can be derived from these plant sources to support humans. Human nutritional requirements information based on current knowledge are developed for inhabitants envisioned in the CELSS ground based demonstrator. Groups of plant products that can provide the nutrients are identified
The supermembrane revisited
The M2-brane is studied from the perspective of superembeddings. We review
the derivation of the M2-brane dynamics and the supergravity constraints from
the standard superembedding constraint and we discuss explicitly the induced
d=3, N=8 superconformal geometry on the worldvolume. We show that the gauged
supermembrane, for a target space with a U(1) isometry, is the standard
D2-brane in a type IIA supergravity background. In particular, the D2-brane
action, complete with the Dirac-Born-Infeld term, arises from the gauged
Wess-Zumino worldvolume 4-form via the brane action principle. The discussion
is extended to the massive D2-brane considered as a gauged supermembrane in a
massive D=11 superspace background. Type IIA supergeometry is derived using
Kaluza-Klein techniques in superspace.Comment: Latex, 46 pages, clarifying remarks and references adde
Nutritional and cultural aspects of plant species selection for a controlled ecological life support system
The feasibility of using higher plants in a controlled ecological life support system is discussed. Aspects of this system considered important in the use of higher plants include: limited energy, space, and mass, and problems relating to cultivation and management of plants, food processing, the psychological impact of vegetarian diets, and plant propagation. A total of 115 higher plant species are compared based on 21 selection criteria
L-branes
The superembedding approach to -branes is used to study a class of
-branes which have linear multiplets on the worldvolume. We refer to these
branes as L-branes. Although linear multiplets are related to scalar multiplets
(with 4 or 8 supersymmetries) by dualising one of the scalars of the latter to
a -form field strength, in many geometrical situations it is the linear
multiplet version which arises naturally. Furthermore, in the case of 8
supersymmetries, the linear multiplet is off-shell in contrast to the scalar
multiplet. The dynamics of the L-branes are obtained by using a systematic
procedure for constructing the Green-Schwarz action from the superembedding
formalism. This action has a Dirac-Born-Infeld type structure for the -form.
In addition, a set of equations of motion is postulated directly in superspace,
and is shown to agree with the Green-Schwarz equations of motion.Comment: revised version, minor changes, references added, 22 pages, no
figures, LaTe
MIT solar wind plasma data from Explorer 33 and Explorer 35: July 1966 to September 1970
The plasma experiments on Explorer 33 and Explorer 35 have yielded large amounts of solar wind data. This report gives a brief review of the method used to obtain the data, provides a description of the plasma parameters, and describes in detail the format of the plots and tapes which are available from the Data Center. Hourly average plots of the data are included at the end of the report. From these plots, the availability and interest of the solar wind data for any period of time may be determined
Deeply penetrating banded zonal flows in the solar convection zone
Helioseismic observations have detected small temporal variations of the
rotation rate below the solar surface corresponding to the so-called `torsional
oscillations' known from Doppler measurements of the surface. These appear as
bands of slower and faster than average rotation moving equatorward. Here we
establish, using complementary helioseismic observations over four years from
the GONG network and from the MDI instrument on board SOHO, that the banded
flows are not merely a near-surface phenomenon: rather they extend downward at
least 60 Mm (some 8% of the total solar radius) and thus are evident over a
significant fraction of the nearly 200 Mm depth of the solar convection zone.Comment: 4 pages, 4 figures To be published in ApJ Letters (accepted 3/3/2000
On superembedding approach to type IIB 7-branes
In search for a dynamical description of Q7-branes, which were known as
solutions of supergravity equations and then conjectured to be dynamical
objects of type IIB string theory, we study the superembedding description of
7-branes in curved type IIB supergravity superspace. With quite minimal and
natural assumptions we have found that there is no place for Q7-branes as
dynamical branes in superembedding approach. Our study might give implications
for the old-standing problem of the covariant and supersymmetric description of
multiple Dp-brane systems.Comment: LaTeX, 40 pages, no figures. V2: 44 pages, misprints corrected, minor
cosmetic changes, improvements and extensions of discussion, in particular in
the parts devoted to derivation of D7-brane equations of motion (Sec. 3) and
in Secs. 4.2; appendices E,F added, footnote on page 30 extended, conclusions
remain the same. V3. More misprints correcte
D=3, N=8 conformal supergravity and the Dragon window
We give a superspace description of D=3, N=8 supergravity. The formulation is
off-shell in the sense that the equations of motion are not implied by the
superspace constraints (but an action principle is not given). The multiplet
structure is unconventional, which we connect to the existence of a "Dragon
window", that is modules occurring in the supercurvature but not in the
supertorsion. According to Dragon's theorem this cannot happen above three
dimensions. We clarify the relevance of this window for going on the conformal
shell, and discuss some aspects of coupling to conformal matter.Comment: plain tex, 24 pp v2: minor change
INVESTIGATING VICTORIA'S INVERSE EQUITY HYPOTHESIS: THE CHANGING SOCIAL EPIDEMIOLOGY OF HIV INFECTION IN TANZANIA
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