8,868 research outputs found
A survey of the problem and research needs in the coastal zone
Coastal zone oceanography emphasizing pollution and geological processes - bibliograph
Spectral and stratigraphic mapping of hydrated sulfate and phyllosilicate-bearing deposits in northern Sinus Meridiani, Mars
We present detailed stratigraphic and spectral analyses that focus on a region in
northern Sinus Meridiani located between 1°N to 5°N latitude and 3°W to 1°E longitude.
Several stratigraphically distinct units are defined and mapped using morphologic
expression, spectral properties, and superposition relationships. Previously unreported
exposures of hydrated sulfates and Fe/Mg smectites are identified using MRO CRISM and
MEX OMEGA nearâinfrared (1.0 to 2.5 ”m) spectral reflectance observations. Layered
deposits with monohydrated and polyhydrated sulfate spectral signatures that occur in
association with a northeastâsouthwest trending valley are reexamined using highresolution
CRISM, HiRISE, and CTX images. Layers that are spectrally dominated by
monohydrated and polyhydrated sulfates are intercalated. The observed compositional
layering implies that multiple wetting events, brine recharge, or fluctuations in evaporation
rate occurred. We infer that these hydrated sulfateâbearing layers were unconformably
deposited following the extensive erosion of preexisting layered sedimentary rocks and
may postdate the formation of the sulfateâ and hematiteâbearing unit analyzed by the MER
Opportunity rover. Therefore, at least two episodes of deposition separated by an
unconformity occurred. Fe/Mg phyllosilicates are detected in units that predate the sulfateand
hematiteâbearing unit. The presence of Fe/Mg smectite in older units indicates that the
relatively low pH formation conditions inferred for the younger sulfateâ and hematitebearing
unit are not representative of the aqueous geochemical environment that prevailed
during the formation and alteration of earlier materials. Sedimentary deposits indicative of
a complex aqueous history that evolved over time are preserved in Sinus Meridiani, Mars
ICT entertainment appliancesâ impact on domestic electricity consumption
Increased electricity consumption and environmental impacts of Information Communication Technology (ICT) have been subjects of research since the 1990s. This paper focuses on consumer electronics in households, in particular TVs, computers and their peripherals. ICT accounts for almost 15% of global domestic electricity use, including waste energy from devices left on standby which is estimated in the EU-27 to contribute 6% of residential energy demand. In Europe, the household electricity consumption from small electronic appliances, including ICT, increased by 2.5 times in 2011 compared to 1990. Similarly, in the UK, energy demand from electronic devices accounted for 23% of total household electricity use in 2012, compared to 12% in 1990. This is an outcome of the market saturation of new, cheaper ICT entertainment devices, facilitated by marketing strategies which identify new needs for consumers, as charted by the review of market growth in this paper. New increasingly portable laptops, smart phones and tablets with wireless connectivity allow householders to perform a wider range of activities in a wider range of locations throughout the home, such as social networking while the television is active. We suggest that policies which consider how to increase the energy efficiency of ICT devices alone are unlikely to be successful since effective strategies need to address how the drivers which have developed around the use of ICT can be adapted in order to conserve electricity in households. A range of policy solutions are discussed, including feedback, public information campaigns, environmental education, energy labelling, bans of, or taxation on the least efficient products as well as the use of a TV as central hub to perform the existing functions of multiple devices
Creation and manipulation of Feshbach resonances with radio-frequency radiation
We present a simple technique for studying collisions of ultracold atoms in
the presence of a magnetic field and radio-frequency radiation (rf). Resonant
control of scattering properties can be achieved by using rf to couple a
colliding pair of atoms to a bound state. We show, using the example of 6Li,
that in some ranges of rf frequency and magnetic field this can be done without
giving rise to losses. We also show that halo molecules of large spatial extent
require much less rf power than deeply bound states. Another way to exert
resonant control is with a set of rf-coupled bound states, linked to the
colliding pair through the molecular interactions that give rise to
magnetically tunable Feshbach resonances. This was recently demonstrated for
87Rb [Kaufman et al., Phys. Rev. A 80:050701(R), 2009]. We examine the
underlying atomic and molecular physics which made this possible. Lastly, we
consider the control that may be exerted over atomic collisions by placing
atoms in superpositions of Zeeman states, and suggest that it could be useful
where small changes in scattering length are required. We suggest other species
for which rf and magnetic field control could together provide a useful tuning
mechanism.Comment: 21 pages, 8 figures, submitted to New Journal of Physic
Bactrocera Cucurbitae response to four Cymbopogon species essential oils
GC/MS analysis of essential oils extracted from four Cymbopogon species revealed that the majors compounds were trans-p-mentha-1(7),8-dien-2-ol (21.9%), cis-p-mentha-1(7),8-den- 2-ol (19.4%), trans-p-mentha-2,8-dien-1-ol (9.6%), cis-p-mentha-2,8-dien-1-ol (7.2%), cis-pmenth-2-en-1-ol (7.2%), limonene (6.3%) in C. giganteus; piperitone (68.4%); ?-2-carene (11.5%) and ?-eudesmol (4.9%) in C. schoenanthus, while citronellal (41.6%); geraniol (28.2%); citronellol (12.6%) and geranial (41.3%); neral (33.0%); myrcene (10.4%), geraniol (6.5%) were recorded in C. nardus and C. citratus, respectively.Tephritid fruit flies use both
olfactory and visual cues to seek food and ovipositional resources. Olfactive effects for C. citratus, C. nardus, C. giganteus and C. schoenanthus essential oils on melon fly (B. cucurbitae) were evaluated using a four-arm olfactometer. The results showed that C. giganteus and C. schoenanthus repel mostly the fruit fly B. cucurbitae, compared with C. nardus and C. citratus and that female and male B. cucurbitae responded similarly to odours emitted from all essential oils evaluated. The number of pupae collected from zucchini treated with C. giganteus was significantly lower than that collected from zucchini treated with C.
nardus when exposed to female B. cucurbitae, regardless of the concentrations
Rotating strings
Analytical expressions are provided for the configurations of an
inextensible, flexible, twistable inertial string rotating rigidly about a
fixed axis. Solutions with trivial radial dependence are helices of arbitrary
radius and pitch. Non-helical solutions are governed by a cubic equation whose
roots delimit permissible values of the squared radial coordinate. Only curves
coplanar with the axis of rotation make contact with it.Comment: added to discussion and made small revisions to tex
Programmed buckling by controlled lateral swelling in a thin elastic sheet
Recent experiments have imposed controlled swelling patterns on thin polymer
films, which subsequently buckle into three-dimensional shapes. We develop a
solution to the design problem suggested by such systems, namely, if and how
one can generate particular three-dimensional shapes from thin elastic sheets
by mere imposition of a two-dimensional pattern of locally isotropic growth.
Not every shape is possible. Several types of obstruction can arise, some of
which depend on the sheet thickness. We provide some examples using the
axisymmetric form of the problem, which is analytically tractable.Comment: 11 pages, 9 figure
Composite bosons in bilayer nu = 1 system: An application of the Murthy-Shankar formalism
We calculate the dispersion of the out-of-phase mode characteristic for the
bilayer nu = 1 quantum Hall system applying the version of Chern-Simons theory
of Murthy and Shankar that cures the unwanted bare electron mass dependence in
the low-energy description of quantum Hall systems. The obtained value for the
mode when d, distance between the layers, is zero is in a good agreement with
the existing pseudospin picture of the system. For d nonzero but small we find
that the mode is linearly dispersing and its velocity to a good approximation
depends linearly on d. This is in agreement with the Hartree-Fock calculations
of the pseudospin picture that predicts a linear dependance on d, and contrary
to the naive Hartree predictions with dependence on the square-root of d. We
set up a formalism that enables one to consider fluctuations around the found
stationary point values. In addition we address the case of imbalanced layers
in the Murthy-Shankar formalism.Comment: 10 pages, 1 figur
Incommensurate ground state of double-layer quantum Hall systems
Double-layer quantum Hall systems possess interlayer phase coherence at
sufficiently small layer separations, even without interlayer tunneling. When
interlayer tunneling is present, application of a sufficiently strong in-plane
magnetic field drives a commensurate-incommensurate (CI)
transition to an incommensurate soliton-lattice (SL) state. We calculate the
Hartree-Fock ground-state energy of the SL state for all values of
within a gradient approximation, and use it to obtain the
anisotropic SL stiffness, the Kosterlitz-Thouless melting temperature for the
SL, and the SL magnetization. The in-plane differential magnetic susceptibility
diverges as when the CI transition is approached
from the SL state.Comment: 12 pages, 7 figures, to be published in Physical Review
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